Ligand-Restricted Strategy for Synthesizing Highly Pairing Dual Atom Catalysts

Ligand-Restricted Strategy for Synthesizing Highly Pairing Dual Atom Catalysts | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Ligand-Restricted Strategy for Synthesizing Highly Pairing Dual Atom Catalysts Limin Wu, Yanfu Ma, Shuhui Liu, Ke Shi, Wenyi Li, Jianing Mao, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5976517/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 24 Oct, 2025 Read the published version in Nature Materials → Version 1 posted You are reading this latest preprint version Abstract Dual atom catalysts (DACs), characterized by high activity and metal utilization, as well as structural diversity with a large variety of catalytic sites, hold immense promise for energy conversion technologies, garnering substantial interest from both academia and industry. However, achieving precise control and manipulation of atomic dispersion, pairing ratios, and interatomic distances in DACs, which significantly affect their multifunctional catalytic properties, remains a significant challenge. Herein, we developed a ligand-restricted strategy for the precise synthesis of highly pairing DACs with tunable atomic distances. This was accomplished by coordinating diamine ligands with dual metal precursors, restricting the pairing and relative positions of two metal atoms on two-dimensional graphitic carbon nitride. The atomic pairing ratio exceeded 82%, with the chain length of diamine molecules effectively regulating the distance between paired atoms. As a demonstration, the pairing Pt 1 -Au 1 DACs exhibited almost three times catalytic activity for nitrate reduction to ammonia compared to their unpaired counterparts. Furthermore, shorter distanced Pt 1 -Au 1 DAC reveals four times activity in photothermal catalyzed hydrogenation reactions than longer ones. This work not only introduces a novel design strategy for the atomic-scale fabrication of complex catalysts but also provides valuable insights into nanoscale reaction mechanisms in heterogeneous catalysis. Physical sciences/Materials science/Nanoscale materials Physical sciences/Nanoscience and technology/Nanoscale materials/Two-dimensional materials Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Atomically dispersed metal catalysts have emerged as novel and promising class of materials in heterogeneous catalysis, thinks to their well-defined structures and high atomic utilization efficiency. 1 – 3 Among these, dual atom catalysts (DACs) stand out due to their high metal loading, versatile combinations of different metal atoms, and a unique microenvironment, which collectively contribute to superior catalytic performance across various reactions compared to single atom catalysts. 4 – 9 Their distinct properties are primarily attributed to numerous active metal atoms, interaction between two metal atoms to alter the adsorption configuration of reactants and intermediates, and synergy effect among metal atoms and support to reduce the reaction barrier. 10 – 14 Various methods such as precursor preselection, thermal migration and sequential deposition have been developed to control the dispersion and location of DACs, 15 , 16 which however couldn’t effectively control the pairing and atomic distance of the two metal atom. Consequently, preparing high-quality and high-pairing-ratio DACs to maximize the above merits is highly desirable but has remained a grand challenge for DACs development. To date, most reported DACs possess an atomic pairing ratio of 30–50%. 17–27 Achieving higher pairing ratios typically requires specialized instruments or binuclear metal complexes. For instance, through atomic layer deposition (ALD) and controlling specific parameter control, the second metal precursor could be selectively deposited onto the first, resulting in homonuclear Pt 2 /graphene DACs with a pairing ratio reaching 70%. 28, 29 Alternatively, binuclear metal complexes, a compound comprising two metal atoms and several specific ligands were adsorbed onto supports by π–π electrostatic interaction and subsequently pyrolyzed to form DACs. 30 – 33 However, these structurally stable ligands need high temperatures for removal, which disrupts metal atom dispersion and lead to the formation of metal particles. Meanwhile, the expensiveness and limited types of commercial binuclear metal complexes restrict wide implementation of these techniques in DACs synthesis. The porous nature of metal-organic frameworks enables the facile preparation of DACs by double or co-impregnation. 24 , 34 – 38 Nevertheless, the complexity of coordination configurations in MOFs often results in numerous randomly dispersed single atoms, complicating the identification of actual active sites and the full utilization of synergistic catalytic effects. Another critical factor influencing catalytic performance is the distance between atomic sites. While this is conceptually straightforward, achieving precise control over atomic distances remains challenging with existing methods. 39 At present, the main approach is to change the metal density by tuning the metal loading. 40 , 41 However, this does not guarantee equidistant dispersion of metal atoms. Therefore, developing a facile method to prepare DACs with both high pairing ratio and tunable distance is essential for advancing the atomic-level understanding of catalytic mechanisms and expanding the repertoire of atomically dispersed metal catalysts. In this work, we introduce a ligand-restricted synthesis strategy for achieving highly pairing homo- and heteronuclear DACs with controllable distances engineered by coordinating diamine ligands with two metal precursors on two-dimensional (2D) graphitic carbon nitride (g-C 3 N 4 ). Our engineered DACs achieve a pairing ratio exceeding 82%, which markedly surpassing previously reported values. Furthermore, we demonstrate the ability to control atomic distances from 0.47 to 0.22 nm by varying the chain length of diamine ligands—a capability not realized by existing methods. As a proof of concept, the pairing atom Pt 1 -Au 1 /g-C 3 N 4 -HA DACs exhibited considerably higher catalytic activity (744 mg h − 1 mg metal −1 ) than the unpairing counterpart (255 mg h − 1 mg metal −1 ) in nitrate reduction to ammonia. Furthermore, shorter distanced Pt 1 -Au 1 DAC reveals higher activity than longer ones in photothermal catalyzed hydrogenation reactions. Our strategy could be used to prepare various homo and heteronuclear Pt-, Au- based DACs. This work not only presents a novel synthesis strategy for the atomic-level manufacturing of complex catalysts but also provides valuable insights into nanoscale reactions in heterogeneous catalysis. 2. Results and discussion Structural characterization of pairing DACs Figure 1 a shows the proposed ligand-restricted strategy for synthesizing highly pairing homo/heteronuclear DACs on g-C 3 N 4 . Linear 1,6-hexanediamine (HA) was used as the ligand with two amine groups to coordinate the two metal precursors. Owing to its abundant N sites and defects, 2D g-C 3 N 4 was employed as the support. 42 For homonuclear Pt 2 /g-C 3 N 4 -HA DACs, one HA molecule could restrict two Pt atoms by forming Pt-HA compounds via dechloriantion (which will be discussed later), which are then adsorbed on the 2D g-C 3 N 4 support by electrostatic interaction. Pt loading is approximately 0.45 wt% based on inductively coupled plasma optical emission spectrometry (ICP-OES) analysis. The X-ray diffraction (XRD) pattern of g-C 3 N 4 showed two well-resolved peaks at 13° and 27.4° (Figure S1 ), which can be indexed as the (100) and (002) of the in-plane structural packing motif of tri-s-triazine units and interlayer stacking of aromatic segments, respectively. 43 , 44 The absence of additional diffraction peaks in the XRD pattern after Pt loading indicated no agglomerated Pt particles. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) was performed on Pt 2 /g-C 3 N 4 -HA to characterize the of Pt atom dispersion status. Numerous bright dots representing the Pt atoms were observed (Figs. 1 b-d and S2a-d). Importantly, many pairing Pt atoms were easily distinguished and are highlighted by white circles in Fig. 1 d. Figure 1 e further displays the magnified corresponding three-dimensional (3D) atom-overlapping Gaussian-function fitting mapping of the area marked by the yellow rectangular box in Fig. 1 c. The pairing feature for Pt 2 /g-C 3 N 4 -HA was clearly shown. In contrast, for the control sample without the HA ligand in Pt 2 /g-C 3 N 4 -none, Pt atoms were randomly dispersed on g-C 3 N 4 with aggregated Pt atoms or sporadically isolated Pt atoms (Figures S2e-h). These findings indicated that HA could restrict the free-moving behavior of Pt atoms in solution and on support by pairing them with two Pt precursors. Thermal treatment conditions on catalysts directly influence the metal dispersion state. When the pyrolysis temperature was increased from 300 o C to 400 o C, a large number of Pt particles, rather than single atoms, were observed on Pt 2 /g-C 3 N 4 -HA-400 (Figure S3), indicating that the metal-support interactions at higher temperatures are insufficient to anchor and disperse Pt atoms, resulting in aggregation with stronger metal-metal interactions. In fact, this interaction varies across metals. Pt 2 /g-C 3 N 4 -HA was dispersed as Pt atomic pairs after calcination at 300 o C. Under the same conditions, Au 2 /g-C 3 N 4 -HA showed numerous Au particles coexisting with Au single/dual atoms (Figure S4). This suggests that the Pt-support interaction dominates the Pt-Pt interaction, while the Au-Au interaction dominates the Au-support interaction. Metal-metal and metal-support interactions are opposite, responsible for metal agglomeration and dispersion, 45 respectively. To obtain atomically dispersed species, it is necessary to fulfill the reaction condition that the metal-support interaction should be stronger than the metal-metal interaction to obtain atomically dispersed species. Unlike homonuclear DACs, the design of heteronuclear DACs requires to the sequential introduction of two different metals near the anchor or defect sites of g-C 3 N 4 . Therefore, Pt single atoms that have strong metal-support interactions are first fixed on the g-C 3 N 4 surface by Pt-N electrostatic interaction. After adding HA ligand, one end amine could coordinate with Pt, and the other end amino group of HA then traps free Au via dechloriantion, finally forming Pt-Au heteronuclear DACs. The weak Au and g-C 3 N 4 interaction makes the thermal treatment temperature critical. When it was decreased from 300 o C to 200 o C, the metal particles were still observed (Figure S5). A further decrease to 150 o C caused the particles to disappear, with numerous atoms regularly arranged in pairs throughout the entire region of Pt 1 -Au 1 /g-C 3 N 4 -HA (Figs. 1 f and S6), which are marked by white circles in Fig. 1 g. The absence of Pt and Au diffraction peaks on the XRD pattern implied that no metal particles were formed (Figure S7). The corresponding 3D atom-overlapping Gaussian-function fitting mapping of the yellow rectangular box in Fig. 1 f reveals the presence of atomic pairs in Pt 1 -Au 1 /g-C 3 N 4 -HA (Fig. 1 h). To exclude the possibility of mistaking neighboring single atoms for atomic pairs, a region with relatively sparse atoms was selected where clearly defined atomic pairs were identified and found clearly atomic pairs (Figure S8a), indicating that HA has a strong pairing effect for Pt and Au. Owing to the similar atomic sequence and contrast between Pt and Au atoms, minor differences existed for two adjacent atoms in the STEM images and local intensity profiles (Figures S8b and c). Note that the atomic sequence is proportional to brightness in the AC-HAADF-STEM test. 46 , 47 For Pt 1 -Ni 1 /g-C 3 N 4 -HA DACs synthesized via a similar procedure, Figs. 1 i, j 1 , and j 2 represent the AC-HAADF-STEM images and the magnified corresponding 3D atom-overlapping Gaussian-function fitting mappings for Pt 1 -Ni 1 /g-C 3 N 4 -HA. Brightness varies slightly for some atomic pairs. After visualization, two neighboring atoms exhibit two peaks of different heights, where the higher peak represents Pt and the lower peak represents Ni due to the different Z-contrasts of Pt (Z = 78) and Ni (Z = 28). The suboptimal quality of Pt 1 -Ni 1 DACs compared to Pt 1 -Au 1 DACs presumably may be related to the metal precursor acidity. The influence of support materials on the dispersion state of single atoms was also examined. When one-dimensional carbon nanotubes (CNTs) were used as supports, many particles were observed on Pt 1 /CNTs and Pt 1 -Au 1 /CNTs-HA (Figures S9a and b), implying that Pt and Au atoms are unstable and tend to agglomerate into large particles, probably due to CNTs curvature. In contrast, the 2D graphene oxide (GO) support also produced atomically dispersed Pt and Au (Figures S9c and d). Therefore, 2D materials are more ideal supports for anchoring metal atomic pairing via our strategy. To better understand the pairing function of HA, the electron-microscopy-based atom recognition statistics (EMARS) methodology was employed to identify the atomic distances of Pt atoms and to count the atom pairing ratio. 48 The minimum distance of one atom with its neighboring atoms was counted. The pairing ratio was expressed as the ratio of the number of pairing atoms to the total number of atoms. For homonuclear Pt 2 /g-C 3 N 4 -HA, the pairing ratio is as high as 83%, which far exceeds those of previously reported DACs, as summarized in Fig. 1 k. 17 – 25 , 29 For heteronuclear, Pt 1 -Au 1 /g-C 3 N 4 -HA, the pairing ratio was 82% (Figure S10) using manual statistics. Thus, the high-quality and atomic-level dispersion of dual atoms can be realized by pairing them with the HA ligand. To illustrate the generality of our strategy, Fig. 2 a summarizes the relationship of metal dispersion state with metal type, support and thermal treatment temperature after the use of HA ligand based on AC-HAADF-STEM images. For elucidating the pairing mechanism, it is crucial to investigate HA ligand and metal precursor interaction. An FTIR experiment was carried out to characterize the interaction between HA and H 2 PtCl 6 . Figure 2 b reveals that N-H and C-N vibrations of HA disappear after H 2 PtCl 6 and HA were mixed for 30 min, indicating that the terminal amino of HA have successfully bonded with Pt species. In addition, density functional theory (DFT) calculation was performed to delve deeper into the pairing mechanism of HA and Pt in the presence of solvent, including the energies and structures of reaction intermediates, and energy barriers in the corresponding transformation process. DFT results demonstrate that the energy is reduced to -3227.2 Ha after the interaction between H 2 PtCl 6 and HA, indicating that the combined structure is more stable. Therefore, HA and H 2 PtCl 6 could spontaneously form a stable Pt-HA compound in water before g-C 3 N 4 addition (Figures S11-12), in line with the FTIR results. Dechlorination process between HA and H 2 PtCl 6 can generate stable bimetallic complexes. For heteronuclear DACs, the HA adsorption behavior on the Pt atom surface is equivalent to the dechlorination process in homonuclear DACs. Therefore, highly pairing homo/heteronuclear DACs can result from HA ligand incorporation. The detailed coordination information of the two Pt atoms in Pt 2 /g-C 3 N 4 -HA is further explored by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO chemisorption, X-ray absorption near-edge spectroscopy (XANES), and extended X-ray fine-structure spectroscopy (EXAFS) spectra. In the DRIFTS spectrum (Figure S13), almost no notable bridge-CO (~ 1830 cm − 1 ) or linear-CO (~ 2090 cm − 1 ) absorption peaks were observed on the Pt 2 /g-C 3 N 4 -HA sample. 49 , 50 This scenario could be caused by low Pt loading. Therefore, a controlled sample with five-fold Pt loading was synthesized. Despite increasing Pt loading, a bridge-bonded CO adsorption peak remained lacking, indicating the absence of Pt particles. Notably, the CO adsorption peak is asymmetric and is located at around 2060 cm − 1 on the Pt dual atom sample, which differs from the CO adsorption peak of the pure single atoms at around 2090 cm − 1 . 51,52 Therefore, an obviously red shift exists in the linear adsorption of CO by Pt dual atoms in the Pt 2 /g-C 3 N 4 -HA. 53 Similarly, the Pt L 3 -edge XANES results (Figure S14) indicated Pt 2 /g-C 3 N 4 -HA had markedly higher white-line intensity than the Pt foil but a lower value than PtO 2 , indicating that the valence state of Pt is between 0 and + 4. 54,55 Additionally, the primary peak at 1.60 Å was assigned to Pt-N coordination in Fig. 2 c. The Pt-Pt characteristic peak at 2.60 Å was not detected in the Pt 2 /g-C 3 N 4 -HA sample, verifying that Pt was almost atomically dispersed in Pt 2 /g-C 3 N 4 -HA sample instead of clusters or nanoparticles, consistent with the DRIFTS results. Pt 1 -Au 1 /g-C 3 N 4 -HA had a higher white-line intensity than the Pt foil but a lower value than PtO 2 (Figure S15a), suggesting that Pt species carried a partial positive charge (Pt δ+ , 0 < δ < 4). 54,55 EXAFS measurement was performed to determine the local structure of the Pt atoms (Fig. 2 d). The Pt L 3 -edge EXAFS of Pt 1 -Au 1 /g-C 3 N 4 -HA displayed one peak at 1.60 Å corresponding to the Pt-N contribution. Compared to the Pt foil, the peak at 2.60 Å (Pt-Pt bond) was not detected. This excludes the formation of metallic Pt nanoparticles and confirms the exclusive presence of isolated Pt atoms, in agreement with the AC-HAADF-STEM results. Furthermore, the normalized Au L 3 -edge XANES curves of Pt 1 -Au 1 /g-C 3 N 4 -HA was between the standard of Au foil and Au 2 O 3 (Figure S15b), indicating the presence of cationic Au species (Au δ+ , 0 < δ < 3). The Au L 3 -edge EXAFS curve showed only one main peak at 1.63 Å (Fig. 2 e), attributed to the Au-N scattering path, instead of the Au-Au bond (2.58 Å). Therefore, Au was present as a single atom species in Pt 1 -Au 1 /g-C 3 N 4 -HA, with no evidence of Au-Au bond forming clusters or nanoparticles, implying that HA and g-C 3 N 4 successfully captured and immobilized the Au atoms. The fitting of the first shell revealed that Pt-N and Au-N had respective coordination numbers of 4.1 ± 0.9 and 1.6 ± 0.1. Unlike Pt 2 /g-C 3 N 4 -HA heated at 300 o C, Pt 1 -Au 1 /g-C 3 N 4 -HA was heated at a lower temperature, so the HA ligand may not be removed. To confirm the presence of HA, we performed a series of attenuated total reflectance infrared experiments on g-C 3 N 4 , Pt 1 -Au 1 /g-C 3 N 4 -none and Pt 1 -Au 1 /g-C 3 N 4 -HA. The characteristic bands of g-C 3 N 4 loaded with Pt and Au remained unchanged compared with those of g-C 3 N 4 . However, some bands at 1250 cm − 1 seemed to be covered on Pt 1 -Au 1 /g-C 3 N 4 -HA (Figure S16). Computationally, Figs. 2 f and g, S17-19 illustrate the electronic structure and adsorption energy of coordinated HA molecule on Pt 1 Au 1 /C 3 N 4 (-3.88 eV), Pt 1 /C 3 N 4 (-1.09 eV) and Au 1 /C 3 N 4 (-2.75 eV) models, indicating the Pt-Au atomic pair is more favorable to anchor and stabilize HA molecule than Pt and Au single atoms with the electronic interaction. The analysis of the charge density differences of the catalyst models indicates obvious charge transfer between metals and C 3 N 4 materials. In particular, the Pt atom in Pt 1 Au 1 /C 3 N 4 had larger electron loss areas (blue region in Figure S19) than Pt 1 /C 3 N 4 , while the Au atom in Pt 1 Au 1 /C 3 N 4 had smaller areas than that of Au 1 /C 3 N 4 , suggesting electron transferability from Pt to Au atoms via C 3 N 4 material. Subsequently, to explore the origin of reaction activity, the average Bader charge of different elements was calculated in the pristine C 3 N 4 , Pt 1 Au 1 /C 3 N 4 , Pt 1 /C 3 N 4 and Au 1 /C 3 N 4 catalyst surfaces (Table S1 ). The Bader charge analysis revealed that the C atoms lost average electrons (-1.63 e − ) and N atoms gained average electrons (+ 1.22 e − ) in pristine C 3 N 4 . After loading Pt and Au in the C 3 N 4 materials, the C and N atoms tended to gain and lose electrons relative to those of pristine C 3 N 4 , becoming − 1.47 and + 1.13 e − , respectively. Pt and Au in Pt 1 Au 1 /C 3 N 4 also lost electrons compared to the corresponding Pt 1 /C 3 N 4 and Au 1 /C 3 N 4 . Hence, we can reasonably infer that the electron transfer order is generally metal site → N atoms → C atoms in three catalyst models, leading to a stronger interaction between the electron-rich -NH 2 groups in the HA molecule and the electron-deficient Pt-Au atomic pair in the catalyst of Pt 1 -Au 1 /g-C 3 N 4 -HA. Moreover, the electrons lost in the of metal active site was − 0.55 e − (Pt site-Pt 1 Au 1 /C 3 N 4 ), − 0.45 e − (Au site-Pt 1 Au 1 /C 3 N 4 ), − 0.36 e − (Pt site-Pt 1 /C 3 N 4 ), and − 0.48 e − (Au site-Au 1 /C 3 N 4 ), respectively. This finding indicates that the Pt atom can transfer electrons to the Au from the N atoms, consistent with the charge density difference calculation results. Therefore, HA should be stably present on Pt 1 -Au 1 /g-C 3 N 4 -HA. To visually illustrate the Pt or Au coordination environments in Pt 2 /g-C 3 N 4 -HA and Pt 1 -Au 1 /g-C 3 N 4 -HA, the wavelet transform (WT) of the k 2 weighted EXAFS spectras, a reflection of structural information in the resolution of R and K spaces, were conducted (Figs. 2 h-n). The Pt L 3 -edge EXAFS further confirms the existence of Pt-N rather than Pt-Pt and Pt-O bonds in Pt 2 /g-C 3 N 4 -HA (Fig. 2 j) and Pt 1 -Au 1 /g-C 3 N 4 -HA (Fig. 2 k), respectively. A similar result was observed in Pt 1 -Au 1 /g-C 3 N 4 -HA (Fig. 2 n). Therefore, for homonuclear DACs, a bimetallic complex is formed and then loaded onto the support (Figure S20). For heteronuclear DACs, one metal is first fixed on the support and is modified with ligand; finally, the other metal is adsorbed and formed into atom pairs (Figure S21). Although a slight difference exists in the reaction pathway, the principle is based on the dechlorination reaction of HA and metal precursors. Regulation of the atomic distance of DACs Insights from Based the formation mechanism discussed above suggest that the ligand chain length can enable precise adjustment of the atomic distance of DACs. To this end, another ligand molecule, ethylenediamine (EA), was used to replace HA and synthesize DACs, denoted as Pt 2 /g-C 3 N 4 -EA. In addition, a sample without ligand was prepared as the control, denoted as Pt 2 /g-C 3 N 4 -none. Lots of pairing bright dots representing Pt atom pairs were easily distinguished from the images of both Pt 2 /g-C 3 N 4 -HA (Fig. 3 a) and Pt 2 /g-C 3 N 4 -EA (Fig. 3 b). For Pt 2 /g-C 3 N 4 -none DACs, all Pt atoms showed random and atomic dispersion without formation of Pt pairs (Fig. 3 c), implying that g-C 3 N 4 can be used to disperse and anchor metal single atoms, while ligands can be utilized to bind metal atoms in pairs at specific spacings. For a better illustration of the effect of diamine compounds on atomic distance modulation, the sub-Ångström accuracy statistical EMASR methodology, 48 was employed to measure and count the atomic distance between pairing Pt/Au atoms at their nearest neighboring coordination. With a total count of > 1950 atoms per sample across all three DACs, the distribution of atomic distance is respectively showed in Figs. 3 d-f. In general, Pt 2 /g-C 3 N 4 -EA has a shorter atomic distance of 0.22 nm than Pt 2 /g-C 3 N 4 -HA (0.47 nm). These distances are very proportional to the chain lengths of ligands EA (0.46 mn) and HA (10.5 nm). To visualize Pt-Pt atomic pairings, atoms with distances of 0-0.33 nm, 0.34–0.66 nm, 0.67–0.99 nm and 1.00–3.00 nm are assigned red, green, blue, and yellow, respectively. Each atom is highlighted with a corresponding colored circle. The color recognition results for Pt 2 /g-C 3 N 4 -HA and Pt 2 /g-C 3 N 4 -none are illustrated in Figs. 3 g and h, and S22. Clearly, many green circles exist in Fig. 3 g, while many red circles appear in Fig. 3 h, suggesting that HA efficiently dictates the distance between pairing Pt atoms. In the absence of HA modification, Pt atoms tend to be randomly anchored at abundant sites on g-C 3 N 4 . Given that the distance between two adjacent N atoms or defects on g-C 3 N 4 is characterized as 0.23 nm, Pt atoms could be anchored at two adjacent sites, either squeezed into the same C 6 N 8 unit cell or separated at two cells (Figure S23). When the Pt precursor is paired with HA or EA, Pt dual atoms are formed with fixed distances (0.47 or 0.22 nm), demonstrating that the ligand size gives precise control over the atomic distances in DACs via our ligand-restricted strategy. Catalytic performance of pairing DACs As the experimental results showed, HA molecule modification enabled the effective binding of Pt and Au atoms, so the electrostatic potential (ESP) of HA was analyzed. In Fig. 4 a, the dark blue region, especially around two -NH 2 radicals in HA, presents strong nucleophilic property that obtain more electrons than red regions, which facilitates interaction with metal atoms. Therefore, the catalytic performances of pairing (Pt 1 -Au 1 /g-C 3 N 4 -HA) and unpairing (Pt 1 -Au 1 /g-C 3 N 4 -none) DACs were evaluated via an electrochemical nitrate reduction reaction (NO 3 − RR). Figures 4 b, S24 and S25 display the NH 3 yield and Faraday efficiency of different DACs. For highly pairing DACs, Pt 1 -Au 1 /g-C 3 N 4 -HA exhibited a superior catalytic performance of 744 mg h − 1 mg metal −1 (i.e., 3347 µg h − 1 mg − 1 ) with 95.6% Faraday efficiency. Yet, the NH 3 yield was just 255 mg h − 1 mg metal −1 on unpairing Pt 1 -Au 1 /g-C 3 N 4 -none DACs. Without the Au atom, Pt 2 /g-C 3 N 4 -none was inactive, showing a very low NH 3 yield. The cycling stability of Pt 1 -Au 1 /g-C 3 N 4 -HA was investigated by performing six successive cycles under optimal reaction conditions. The NH 3 yield and Faraday efficiency foscillated within a small range but generally remained stable (Fig. 4 c). The NH 3 yield decreased slightly after the second cycle. The Pt 1 -Au 1 /g-C 3 N 4 -HA also exhibited favorable stability without a notable decrease in NH 3 yield during the long-term electrolysis test for 15 h (Figure S26). These results imply that increasing the pairing ratio of DACs can markedly enhance the catalytic activity in NO 3 − RR. To further investigate the relationship between electronic structures and the NO 3 − RR performance of the Pt 1 -Au 1 /g-C 3 N 4 -HA catalyst, all possible reaction mechanisms were proposed and calculated by the DFT simulations (Figures S27-29). For Pt 1 /C 3 N 4 and Au 1 /C 3 N 4 models, the potential-determining-step (PDS) with the highest Gibbs free energy change (∆ G ) were the protonation reactions of *NO + H + + e − → *NHO and *NO 3 + H + + e − → *NO 3 H, respectively, with ∆ G in PDS of 0.68 and 1.00 eV (Figures S30-37). However, for Pt 1 Au 1 /C 3 N 4 , *NO 3 + H + + e − → *NO 3 H could occur on the Pt site, after which *NO 2 spontaneously transferred to the Au site with an exothermicity of 0.21 eV. The new PDS was *NO 2 + H + + e − → *NO 2 H, with a ∆ G of 0.43 eV (Fig. 4 d). Therefore, for heteronuclear DACs, a higher pairing ratio means a more desirable synergy between the two metal active sites, which maximizes the catalytic potential of DACs. In addition, regulating atomic distance is also important and advanced for investigating the catalytic performance over atomically dispersed catalyst. Since Au features localized surface plasmon resonance (LSPR), another probe reaction (i.e., the photothermal selective hydrogenation of phenylacetylene) was carried out on Pt 1 -Au 1 /g-C 3 N 4 -HA and Pt 1 -Au 1 /g-C 3 N 4 -EA to study the effect of atomic distance on catalytic performance. The activity results show that the activity of Pt 1 -Au 1 /g-C 3 N 4 -EA is about 4-fold higher than that of Pt 1 -Au 1 /g-C 3 N 4 -HA (Figures S37a, b), implying that the contribution of LSPR is more pronounced at closer atomic distances and favors higher catalytic activity in photothermal selective hydrogenation of phenylacetylene. Therefore, regulating atomic distance is important and advanced for atomic-level designing and investigating highly efficient catalyst. 3. Conclusion Through experiments and theoretical analyses conducted, we have demonstrated that the developed ligand-restricted strategy can effectively fabricate highly paired homonuclear and heteronuclear DACs. Leveraging the efficient electrostatic coordination interaction between metal atoms and the nucleophilic nitrogen atoms of diamine ligands and 2D supports, the pairing ratio achieved exceeded 82%, significantly outperforming previously reported DACs. By modulating the ligand size, precise control over atomic distances in DACs was achieved, ranging from 0.47 to 0.22 nm. As a model system, the highly pairing Pt 1 -Au 1 /g-C 3 N 4 -HA exhibited around three times catalytic activity (744 mg h⁻¹ mgₘₑₜₐₗ⁻¹) in NO₃ − RR, far surpassing the performance of the unpaired Pt 1 -Au 1 /g-C 3 N 4 -none (255 mg h⁻¹ mgₘₑₜₐₗ⁻¹). This enhanced activity is attributed to high-quality two-site synergistic catalysis. Furthermore, shorter distanced Pt 1 -Au 1 /g-C 3 N 4 -EA exhibited higher activity than Pt 1 -Au 1 /g-C 3 N 4 -HA in photothermal catalyzed hydrogenation reactions. Our strategy could be used to prepare various homo and heteronuclear Pt-, Au- based DACs. This study introduces a novel design strategy for the precise and efficient control of metal dispersion at the atomic level, offering both accessibility and practicality for advanced catalytic applications. 4. Experimental section Synthesis of g-C 3 N 4 . Typically, 30 g urea was placed in an alumina crucible and calcined to 550°C at a rate of 5°C min − 1 and kept for 4 h in a static air atmosphere, which was then cooled down to room temperature to obtain a light-yellow powder denoted as g-C 3 N 4 . Synthesis of homonuclear Pt 2 /g-C 3 N 4 -HA DACs and Au 2 /g-C 3 N 4 -HA samples. To synthesize Pt 2 /g-C 3 N 4 -HA, 0.1 M H 2 PtCl 6 ·6H 2 O aqueous solution was added to 20 mL of water, followed by adding 0.1 M HA aqueous solution with a Pt:N molar ratio of 1:1 under magnetic stirring for 30 min. Subsequently, 400 mg of g-C 3 N 4 powders was dispersed in the above mixture and kept stirring for another 24 h. After that, the suspension was heated at 80 o C to remove water. The obtained material was dried at 60°C overnight, then calcined in N 2 at 300°C for 2 h with a heating rate of 5°C min − 1 . The final product was denoted as Pt 2 /g-C 3 N 4 -HA. The calcination temperature increased to 400°C to get Pt 2 /g-C 3 N 4 -HA-400. Correspondently, Au 2 /g-C 3 N 4 -HA samples was synthesized via a similar procedure to that of Pt 2 /g-C 3 N 4 -HA except that H 2 PtCl 6 ·6H 2 O was replaced with HAuCl 4 ·4H 2 O. As a control, Pt 2 /g-C 3 N 4 -none was also prepared in a similar procedure described above without adding HA. Pt 2 /g-C 3 N 4 -HA was prepared by EA instead of HA ligand. Synthesis of heteronuclear Pt 1 -Au 1 /g-C 3 N 4 -HA DACs. Typically, 120 µL of 0.1 M H 2 PtCl 6 ·6H 2 O aqueous solution was added to 120 mL of water under constant stirring to get a homogeneous solution. Then, 400 mg of g-C 3 N 4 was added to the above solution with continuous stirring for 24 h. After that, the above mixture was heated at 80 o C to remove water solvent, dried at 60°C overnight, and then calcinated in N 2 at 300°C for 2 h with a heating rate of 5°C min − 1 . It is notable that periodic triangular defects of g-C 3 N 4 serving as ideal anchor sites could enable dispersion of pioneering Pt at atomic scale by facile wetness impregnation. Next, as-prepared Pt 1 /g-C 3 N 4 SACs was subjected to decoration procedure prior to invite the second atom. Specifically, 300 mg of Pt 1 /g-C 3 N 4 SACs was dispersed to 15 mL of water with agitated stirring. Then, 75.6 µL of 0.1 M HA aqueous solution was dropped into the above suspension. After stirred for 1 h, 15 µL of 0.1 M HAuCl 4 ·4H 2 O aqueous solution was introduced into the above-resulting mixture and stirred for another 23 h. After completely evaporated at 80°C and dried overnight, the collected material was calcined under N 2 at 150 o C or 200 o C for 1 h with a heating rate of 5°C min − 1 to obtain the final product denoted as Pt 1 -Au 1 /g-C 3 N 4 -HA and Pt 1 -Au 1 /g-C 3 N 4 -HA-200, respectively. For comparison, Pt 1 -Au 1 /CNTs-HA and Pt 1 -Au 1 /GO-HA were prepared in a similar process except that the g-C 3 N 4 was replaced by CNTs and GO, respectively. Furthermore, Pt 1 -Au 1 /g-C 3 N 4 -none was also constructed based on the above typical preparation strategy without adding HA. Synthesis of heteronuclear Pt 1 -Ni 1 /g-C 3 N 4 -HA DACs. The synthesis procedure of Pt 1 -Ni 1 /g-C 3 N 4 -HA was similar to that of Pt 1 -Au 1 /g-C 3 N 4 -HA, except that HAuCl 4 ·4H 2 O aqueous solution was replaced by 8.7 mg NiCl 2 ·6H 2 O. Electrocatalytic nitrate reduction. All electrochemical measurements were carried out at room temperature in a typical H-type cell, which is separated into two chambers by a Nafion 211 membrane. A CHI 760E electrochemical workstation electrochemical was used to control the electrolysis reaction. The Hg/HgO reference electrode and the working electrode were placed in the cathode chamber, while the platinum plates (2 cm × 2 cm) counter electrode was placed in the anode chamber. The working electrode was prepared as follows: 6 mg samples, 960 µL ethanol, and 40 µL Nafion solution (5 wt%) were mixed and ultra-sonicated for 1 h to get a homogeneous catalyst ink. Then, a proper volume of ink was dropped onto carbon paper with a loading of 0.5 mg cm − 2 . 0.1 M KOH electrolyte (60 mL, pH = 13.1) was equally distributed to the anode and cathode chambers. This alkaline electrolyte can not only inhibit the side HER, but also facilitates the migration and activation of NO 3 − . On the other hand, the potentials in this study were converted to the reversible hydrogen electrode (RHE) potential: E RHE = E Hg/HgO +0.098 V + 0.059 pH. Therefore, the slight fluctuation of the pH of the alkaline electrolyte during the reaction has little effect on the working potential. The size of the working electrode immersed in electrolyte is 1 × 1 cm 2 . For the electrochemical NO 3 − RR, KNO 3 was added to the cathode electrolyte (containing 7.14 mM NO 3 − ). During the reaction, a high-purity argon flow (10 mL min − 1 ) was continuously injected into the cathode cell, and the electrolyte was stirred at a rate of 200 rpm. NO 3 − RR experiments were carried out at different potentials for 1 h to evaluate the performance of the catalyst. The linear sweep voltammetry (LSV) was conducted at a rate of 5 mV s − 1 . EIS was performed at − 0.2 V vs. RHE from 0.01 to 105 Hz, and the AC amplitude was set to 10 mV. For the stability test, the NO 3 − RR was carried out at − 0.2 V vs. RHE at a stirring rate of 200 rpm. The electrolyte solution was changed every 3 h, and the above experiment was repeated 5 times with the same working electrode. All current densities reported in this work are based on geometric surface area. Declarations Acknowledgements Financial support for this research from the National Natural Science Foundation of China (52033003, 22279139, 62227815), the National Key Research and Development Program of China (2022YFA1205200), Program of Higher-level Talents of IMU (10000-23112101/173), Project of Grassland Talent of Inner Mongolia Autonomous Region (12000-12102805) and Natural Science Foundation of Inner Mongolia Autonomous Region of China (20241Q06). The authors thank Dr. Peng-Cheng Chen, Dr. Yue Gu for helpful discussion. Author contributions L.J. and L.W. supervised the project. Y.M. carried out the synthesis, characterization and catalytic measurements and collaborated in writing the manuscript. S.L. and W.L. contributed with EMARS methodology. W.Z., R.Z., K.S. and R.G. performed the DFT calculations and analysis. W.L. carried out the catalytic performance. J.M. and Z.J. performed the XAS measurement and analysed the data. Y.M., Y.Z. and W.L. performed the AC-HAADF-STEM characterization. The paper was written by Y.M., G.L., J.L and L.W. All authors commented on the manuscript. Additional information Supplementary information is available in the online version of the paper. Reprints and permissions information is available online at www.nature.com/reprints. Correspondence and requests for materials should be addressed to J.L. Competing financial interests The authors declare no competing financial interests. References Wang A, Li J, Zhang T (2018) Heterogeneous single-atom catalysis. Nat Rev Chem 2:65–81 Lang R et al (2020) Single-atom catalysts based on the metal-oxide interaction. Chem Rev 120:11986–12043 Li J, Stephanopoulos MF, Xia Y, Introduction (2020) Heterogeneous single-atom catalysis. Chem Rev 120:11699–11702 Zhang S et al (2023) Atomically dispersed bimetallic Fe-Co electrocatalysts for green production of ammonia. Nat Sustain 6:169–179 Jung E et al (2020) Atomic-level tuning of Co-N-C catalyst for high-performance electrochemical H 2 O 2 production. Nat Mater 19:436–442 Zhang S et al (2023) Fe/Cu diatomic catalysts for electrochemical nitrate reduction to ammonia. Nat Commun 14:3634 Li R, Wang D (2022) Superiority of dual-atom catalysts in electrocatalysis: One step further than single-atom catalysts. Adv Energy Mater 12:2103564 Huang F et al (2022) Low-temperature acetylene semi-hydrogenation over the Pd 1 -Cu 1 dual-atom catalyst. J Am Chem Soc 144:18485–18493 Ma YF, Wang LW, Liu J (2022) Single atom catalysts in liquid phase selective hydrogenations. Chem Res Chin Univ 38:1163–1171 Wei X et al (2021) Cu acting as Fe activity promoter in dual-atom Cu/Fe-NC catalyst in CO2RR to C1 products. Appl Surf Sci 564:150423 Liang X-M, Wang H-J, Zhang C, Zhong D-C, Lu T-B (2023) Controlled synthesis of a Ni 2 dual-atom catalyst for synergistic CO 2 electroreduction. Appl Catal B 322:122073 Jiao J et al (2019) Copper atom-pair catalyst anchored on alloy nanowires for selective and efficient electrochemical reduction of CO 2 . Nat Chem 11:222–228 Li R, Wang D (2022) Understanding the structure-performance relationship of active sites at atomic scale. Nano Res 15:6888–6923 Liu M et al (2024) Cascade Synthesis of Fe-N 2 -Fe Dual-Atom Catalysts for Superior Oxygen Catalysis. Angew Chem Int Ed 63:e202408914 Zhang W et al (2021) Emerging dual-atomic-site catalysts for efficient energy catalysis. Adv Mater 33:2102576 Chen Y et al (2023) Inter-metal interaction of dual-atom catalysts in heterogeneous catalysis. Angew Chem Int Ed 62:e202306469 Wei YS et al (2020) Fabricating dual-atom iron catalysts for efficient oxygen evolution reaction: A heteroatom modulator approach. Angew Chem Int Ed 132:2–11 Lu Z et al (2019) An isolated zinc-cobalt atomic pair for highly active and durable oxygen reduction. Angew Chem Int Ed 58:2622–2626 Ding T et al (2021) Atomically precise dinuclear site active toward electrocatalytic CO 2 reduction. J Am Chem Soc 143:11317–11324 Zhang YX et al (2023) General synthesis of a diatomic catalyst library via a macrocyclic precursor-mediated approach. J Am Chem Soc 145:4819–4827 Xie P et al (2022) Oxo dicopper anchored on carbon nitride for selective oxidation of methane. Nat Commun 13:1375 Chen C et al (2023) Adjacent Fe site boosts electrocatalytic oxygen evolution at Co site in single-atom-catalyst through a dual-metal-site design. Energy Environ Sci 16:1685–1696 Yu D et al (2021) Dual-sites coordination engineering of single atom catalysts for flexible metal-air batteries. Adv Energy Mater 11:2101242 Zhang L et al (2023) Enhanced oxygen reduction activity and stability of double-layer nitrogen-doped carbon catalyst with abundant Fe-Co dual-atom sites. Nano Energy 117:108854 Zhao E et al (2025) Diatomic palladium catalyst for enhanced photocatalytic water-donating transfer hydrogenation. J Am Chem Soc 147:2029–2036 Wang X et al (2020) Confined Fe-Cu clusters as sub-nanometer reactors for efficiently regulating the electrochemical nitrogen reduction reaction. Adv Mater 32:2004382 Gong F et al (2023) Universal sub-nanoreactor strategy for synthesis of yolk-shell MoS 2 supported single atom electrocatalysts toward robust hydrogen evolution reaction. Angew Chem Int Ed 62:e202308091 Lu J (2022) Atomic Lego Catalysts Synthesized by Atomic Layer Deposition. Acc Mater Res 3:358–368 Yan H et al (2017) Bottom-up precise synthesis of stable platinum dimers on graphene. Nat Commun 8:1070 Ye W et al (2019) Precisely tuning the number of Fe atoms in clusters on N-doped carbon toward acidic oxygen reduction reaction. Chem 5:2865–2878 Zhang N et al (2021) A supported Pd 2 dual-atom site catalyst for efficient electrochemical CO 2 reduction. Angew Chem Int Ed 60:13388–13393 Li Y et al (2020) Dual-atom Ag 2 /graphene catalyst for efficient electroreduction of CO 2 to CO. Appl Catal B 268:118747 Tian S et al (2018) Carbon nitride supported Fe 2 cluster catalysts with superior performance for alkene epoxidation. Nat Commun 9:2353 Wang J et al (2017) Design of N-coordinated dual-metal sites: A stable and active Pt-free catalyst for acidic oxygen reduction reaction. J Am Chem Soc 139:17281–17284 Wang J et al (2018) Synergistic effect of well-defined dual sites boosting the oxygen reduction reaction. Energy Environ Sci 11:3375–3379 Ren W et al (2019) Isolated diatomic Ni-Fe metal-nitrogen sites for synergistic electroreduction of CO 2 . Angew Chem Int Ed 58:6972–6976 Tang T et al (2023) Dual-atom Co-Fe catalysts for oxygen reduction reaction. Chin J Catal 46:48–55 Han X et al (2019) Atomically dispersed binary Co-Ni sites in nitrogen-doped hollow carbon nanocubes for reversible oxygen reduction and evolution. Adv Mater 31:1905622 Li WH, Yang J, Wang D (2022) Long-range interactions in diatomic catalysts boosting electrocatalysis. Angew Chem Int Ed 61:e202213318 Meng X et al (2020) Distance synergy of MoS 2 -confined rhodium atoms for highly efficient hydrogen evolution. Angew Chem Int Ed 132:10588–10593 Jiang S et al (2024) Visualization of the distance-dependent synergistic interaction in heterogeneous dual-site catalysis. J Am Chem Soc 146:29084–29093 Ong WJ, Tan LL, Ng YH, Yong ST, Chai SP (2016) Graphitic carbon nitride (g-C 3 N 4 )-based photocatalysts for artificial photosynthesis and environmental remediation: Are we a step closer to achieving sustainability? Chem Rev 116:7159–7329 Tian X et al (2019) Surface P atom grafting of g-C 3 N 4 for improved local spatial charge separation and enhanced photocatalytic H 2 production. J Mater Chem A 7:7628–7635 Yang X et al (2016) Facile fabrication of acidified g-C 3 N 4 /g-C 3 N 4 hybrids with enhanced photocatalysis performance under visible light irradiation. Appl Catal B 193:22–35 Tairan, Wang et al (2024) Nature of metal-support interaction for metal catalysts on oxide supports. Science 386:915–920 Jiao L et al (2021) Non-bonding interaction of neighboring Fe and Ni single-atom pairs on MOF-derived N-doped carbon for enhanced CO 2 electroreduction. J Am Chem Soc 143:19417–19424 Wang B et al (2024) A general metal ion recognition strategy to mediate dual-atomic-site catalysts. J Am Chem Soc 146:24945–24955 Liu S et al (2021) Identify the activity origin of Pt single-atom catalyst via atom-by-atom counting. J Am Chem Soc 143:15243–15249 Ma YF et al (2019) Tailoring of the proximity of platinum single atoms on CeO 2 using phosphorus boosts the hydrogenation activity. ACS Catal 9:8404–8412 Cao S et al (2020) High-loading single Pt atom sites Pt-O(OH)(x) catalyze the CO PROX reaction with high activity and selectivity at mild conditions. Sci Adv 6:eaba3809 Ding K et al (2015) Identification of active sites in CO oxidation and water-gas shift over supported Pt catalysts. Science 350:189–192 Nie L et al (2017) Activation of surface lattice oxygen in single-atom Pt/CeO 2 for low-temperature CO oxidation. Science 358:1419–1423 Gao R et al (2021) Pt/Fe 2 O 3 with Pt-Fe pair sites as a catalyst for oxygen reduction with ultralow Pt loading. Nat Energy 6:614–623 Zhang B et al (2016) Stabilizing a platinum1 single-atom catalyst on supported phosphomolybdic acid without compromising hydrogenation activity. Angew Chem Int Ed 55:8319–8323 Macino M et al (2019) Tuning of catalytic sites in Pt/TiO 2 catalysts for the chemoselective hydrogenation of 3-nitrostyrene. Nat Catal 2:873–881 Additional Declarations There is NO Competing Interest. Supplementary Files Supportinginformationfinal.docx Supporting Information Cite Share Download PDF Status: Published Journal Publication published 24 Oct, 2025 Read the published version in Nature Materials → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5976517","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":415114086,"identity":"248df754-b942-4d32-b48e-e5b03c3802fa","order_by":0,"name":"Limin Wu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAsklEQVRIiWNgGAWjYBACPgYGxgcVDMxgjgRRWtgYGJgNzpCqhU2CRC1iZ8wqDrZZy5szMB+8zcNgl0dYi3SO2Y2DbemGOxvYkq15GJKLidCSu+32x7bDjBsO8JhJ8zAcSGwgRkvBwbbD9hsO8H8jXgsDUEsi0BY2YrXkf5Y4cC49ecNhNmPLOQbJhLXwS6clfjhQZm274XjzwxtvKuwIa0EAcNQYEK9+FIyCUTAKRgEeAADVkjiTjVDVTgAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0001-8495-8627","institution":"Fudan University","correspondingAuthor":true,"prefix":"","firstName":"Limin","middleName":"","lastName":"Wu","suffix":""},{"id":415114087,"identity":"d606df19-c5d3-4bd2-9b42-6b2189861d18","order_by":1,"name":"Yanfu Ma","email":"","orcid":"","institution":"Inner Mongolia University","correspondingAuthor":false,"prefix":"","firstName":"Yanfu","middleName":"","lastName":"Ma","suffix":""},{"id":415114088,"identity":"86bf929c-f5ea-4f2d-bb36-b57ba304f58f","order_by":2,"name":"Shuhui Liu","email":"","orcid":"","institution":"Dalian Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Shuhui","middleName":"","lastName":"Liu","suffix":""},{"id":415114089,"identity":"b3e90f6f-7a3d-48e2-80a4-5d7259f7bdc7","order_by":3,"name":"Ke Shi","email":"","orcid":"","institution":"Inner Mongolia University","correspondingAuthor":false,"prefix":"","firstName":"Ke","middleName":"","lastName":"Shi","suffix":""},{"id":415114090,"identity":"89e99326-36d9-4746-b0f2-9c22f9459bdc","order_by":4,"name":"Wenyi Li","email":"","orcid":"","institution":"Institute of Solid State Physics","correspondingAuthor":false,"prefix":"","firstName":"Wenyi","middleName":"","lastName":"Li","suffix":""},{"id":415114091,"identity":"82d93069-a0c7-4a6e-98fa-d2372a41a484","order_by":5,"name":"Jianing Mao","email":"","orcid":"","institution":"Shanghai Institute of Applied Physic","correspondingAuthor":false,"prefix":"","firstName":"Jianing","middleName":"","lastName":"Mao","suffix":""},{"id":415114092,"identity":"ce0fbe91-ed21-4d3a-8e02-290ce960131d","order_by":6,"name":"Wantong Zhao","email":"","orcid":"","institution":"Taiyuan University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Wantong","middleName":"","lastName":"Zhao","suffix":""},{"id":415114093,"identity":"66e896c7-3313-4cc8-9cd4-49884bcb1cee","order_by":7,"name":"Jieqiong Shan","email":"","orcid":"","institution":"City University of Hong Kong","correspondingAuthor":false,"prefix":"","firstName":"Jieqiong","middleName":"","lastName":"Shan","suffix":""},{"id":415114094,"identity":"1d0b5efd-2e19-4551-a343-cd35c2f444c9","order_by":8,"name":"Yang Zhao","email":"","orcid":"","institution":"Dalian Institute of Chemical Physics","correspondingAuthor":false,"prefix":"","firstName":"Yang","middleName":"","lastName":"Zhao","suffix":""},{"id":415114095,"identity":"acddab85-f381-45a9-ae47-a840f31e66d1","order_by":9,"name":"Zheng Jiang","email":"","orcid":"https://orcid.org/0000-0003-4297-464X","institution":"University of Science and Technology of China","correspondingAuthor":false,"prefix":"","firstName":"Zheng","middleName":"","lastName":"Jiang","suffix":""},{"id":415114096,"identity":"321dbe03-a4a5-45a4-add5-d4d9413829cb","order_by":10,"name":"Riguang Zhang","email":"","orcid":"https://orcid.org/0000-0001-8956-8425","institution":"Taiyuan University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Riguang","middleName":"","lastName":"Zhang","suffix":""},{"id":415114097,"identity":"c15f5886-65a3-4126-9dc8-42b166230c5c","order_by":11,"name":"Rui Gao","email":"","orcid":"","institution":"Inner Mongolia University","correspondingAuthor":false,"prefix":"","firstName":"Rui","middleName":"","lastName":"Gao","suffix":""},{"id":415114098,"identity":"59bed540-9950-4c6a-8a9a-46f428ffdd56","order_by":12,"name":"Wei Liu","email":"","orcid":"https://orcid.org/0000-0002-4403-737X","institution":"Dalian Institute of Chemical Physics, Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Wei","middleName":"","lastName":"Liu","suffix":""},{"id":415114099,"identity":"a16cb219-986b-46bb-a66a-86c74d2cf1a6","order_by":13,"name":"Gaoqing Lu","email":"","orcid":"","institution":"The University of Surrey","correspondingAuthor":false,"prefix":"","firstName":"Gaoqing","middleName":"","lastName":"Lu","suffix":""},{"id":415114100,"identity":"77c64d84-0c38-447c-99d9-60f0477e5548","order_by":14,"name":"Jian Liu","email":"","orcid":"https://orcid.org/0000-0002-5114-0404","institution":"Inner Mongolia University","correspondingAuthor":false,"prefix":"","firstName":"Jian","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2025-02-06 22:30:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5976517/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5976517/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41563-025-02385-6","type":"published","date":"2025-10-24T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":76291390,"identity":"386f3403-c979-462d-aa36-f9dbb6c3609e","added_by":"auto","created_at":"2025-02-14 12:16:08","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1806057,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMicroscopy analysis and structural characterization of\u003c/strong\u003e \u003cstrong\u003eDACs. \u003c/strong\u003e(a)\u003cstrong\u003e \u003c/strong\u003eSchematic illustration for the synthesis of DACs. AC-HAADF-STEM images of (b-d) Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, (f,g) Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, and (i) Pt\u003csub\u003e1\u003c/sub\u003e-Ni\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, respectively. (e, i, j) 3D atom-overlapping Gaussian-function fitting map in \u003cstrong\u003ec\u003c/strong\u003e, \u003cstrong\u003ef\u003c/strong\u003e, and \u003cstrong\u003ei\u003c/strong\u003e, respectively. (k) Comparison of pairing ratios of the Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA with recently published DACs catalysts.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-5976517/v1/dc7aed4c76c9df1a74532087.png"},{"id":76290338,"identity":"5781447b-71ae-457f-92ce-12b76decea0b","added_by":"auto","created_at":"2025-02-14 12:08:08","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":584742,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePairing mechanism and coordination environments of DACs.\u003c/strong\u003e (a) Summary of representative catalyst preparation conditions and their atomic distribution states. (b) FTIR spectroscopy results of HA, H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e and their mixture with different times, respectively. Normalized the \u003cem\u003eK\u003c/em\u003e\u003csup\u003e3\u003c/sup\u003e-weighted Fourier transform spectra of (c) Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, (d) Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA at the Pt L\u003csub\u003e3\u003c/sub\u003e-edge EXAFS spectra and (e) Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA at Au L\u003csub\u003e3\u003c/sub\u003e-edge EXAFS spectra. Reference samples of Pt foil, PtO\u003csub\u003e2\u003c/sub\u003e, Au foil and Au\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e are also showed for comparison. (f) The side view structures of HA adsorbed on the model of Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e catalyst, in which the yellow and red represents the electron accumulation areas, while the cyan and blue represents the electron loss areas. (g) The corresponding adsorption energy of HA is labeled with the bold black numbers above the structure. (h-k) Wavelet transform plots for Pt element of PtO\u003csub\u003e2\u003c/sub\u003e, Pt foil, Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, respectively. (l-n) Wavelet transform plots for Au element of Au\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Au foil and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, respectively.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-5976517/v1/ab9a5b51f4d1d473d5d18af5.png"},{"id":76290343,"identity":"1cda754c-afb7-484b-bfc2-d1614839ec3d","added_by":"auto","created_at":"2025-02-14 12:08:08","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":694844,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRegulation of atomic distance with different ligands.\u003c/strong\u003e AC-HAADF-STEM images of (a) Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, (b) Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-EA and (c) Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none, respectively. Schematic diagram of atomic distance distribution of Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-EA and Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none, respectively. Recognition result with different colors of (g) Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA and (h) Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none. Atoms at distances of 0~0.33 nm, 0.34~0.66 nm, 0.67~0.99 nm and 1.00~3.00 nm are red, green, blue and yellow colors, respectively. Each atom is highlighted with a circle of the same color.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-5976517/v1/f4342c25583c2175e1927fec.png"},{"id":76290345,"identity":"b21dc2e9-4408-4c59-b494-e45bcb4bf96e","added_by":"auto","created_at":"2025-02-14 12:08:08","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":499670,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStructure-activity relationships for Pt\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e-Au\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e/g-C\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e-HA.\u003c/strong\u003e (a) The ESP of HA molecule. The negative ESP value indicating that the dark blue region is more likely to give electrons while the positive value shows that red region possesses the ability to obtain electrons. (b) NH\u003csub\u003e3\u003c/sub\u003e yield and Faradaic efficiency for different catalysts at -0.3 V in 1.0 M KOH with 1000 ppm NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e. (c) The cycling tests of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA for reduction tests at -0.3 V. (d) The Gibbs free energy diagrams (U=0 V) of the most favorable NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003eRR reaction pathways on the Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-5976517/v1/a38f3e4485c5834523a76d24.png"},{"id":94433348,"identity":"1142fbf9-b4dd-43f7-90b7-e233eb623e6c","added_by":"auto","created_at":"2025-10-27 14:18:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4813238,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5976517/v1/b4ca2cb6-7c8f-4919-bbfb-678fbeeb0a58.pdf"},{"id":76290348,"identity":"067fb8b7-deea-44fb-ae02-b77193f84444","added_by":"auto","created_at":"2025-02-14 12:08:09","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":11290326,"visible":true,"origin":"","legend":"Supporting Information","description":"","filename":"Supportinginformationfinal.docx","url":"https://assets-eu.researchsquare.com/files/rs-5976517/v1/fbabf39cb4c55237b9cf7bc7.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Ligand-Restricted Strategy for Synthesizing Highly Pairing Dual Atom Catalysts","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAtomically dispersed metal catalysts have emerged as novel and promising class of materials in heterogeneous catalysis, thinks to their well-defined structures and high atomic utilization efficiency.\u003csup\u003e\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e Among these, dual atom catalysts (DACs) stand out due to their high metal loading, versatile combinations of different metal atoms, and a unique microenvironment, which collectively contribute to superior catalytic performance across various reactions compared to single atom catalysts.\u003csup\u003e\u003cspan additionalcitationids=\"CR5 CR6 CR7 CR8\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e Their distinct properties are primarily attributed to numerous active metal atoms, interaction between two metal atoms to alter the adsorption configuration of reactants and intermediates, and synergy effect among metal atoms and support to reduce the reaction barrier.\u003csup\u003e\u003cspan additionalcitationids=\"CR11 CR12 CR13\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e Various methods such as precursor preselection, thermal migration and sequential deposition have been developed to control the dispersion and location of DACs,\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e which however couldn\u0026rsquo;t effectively control the pairing and atomic distance of the two metal atom. Consequently, preparing high-quality and high-pairing-ratio DACs to maximize the above merits is highly desirable but has remained a grand challenge for DACs development.\u003c/p\u003e \u003cp\u003eTo date, most reported DACs possess an atomic pairing ratio of 30\u0026ndash;50%.\u003csup\u003e17\u0026ndash;27\u003c/sup\u003e Achieving higher pairing ratios typically requires specialized instruments or binuclear metal complexes. For instance, through atomic layer deposition (ALD) and controlling specific parameter control, the second metal precursor could be selectively deposited onto the first, resulting in homonuclear Pt\u003csub\u003e2\u003c/sub\u003e/graphene DACs with a pairing ratio reaching 70%.\u003csup\u003e28, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e Alternatively, binuclear metal complexes, a compound comprising two metal atoms and several specific ligands were adsorbed onto supports by π\u0026ndash;π electrostatic interaction and subsequently pyrolyzed to form DACs.\u003csup\u003e\u003cspan additionalcitationids=\"CR31 CR32\" citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e However, these structurally stable ligands need high temperatures for removal, which disrupts metal atom dispersion and lead to the formation of metal particles. Meanwhile, the expensiveness and limited types of commercial binuclear metal complexes restrict wide implementation of these techniques in DACs synthesis. The porous nature of metal-organic frameworks enables the facile preparation of DACs by double or co-impregnation.\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e,\u003cspan additionalcitationids=\"CR35 CR36 CR37\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e Nevertheless, the complexity of coordination configurations in MOFs often results in numerous randomly dispersed single atoms, complicating the identification of actual active sites and the full utilization of synergistic catalytic effects.\u003c/p\u003e \u003cp\u003eAnother critical factor influencing catalytic performance is the distance between atomic sites. While this is conceptually straightforward, achieving precise control over atomic distances remains challenging with existing methods.\u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e At present, the main approach is to change the metal density by tuning the metal loading.\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e However, this does not guarantee equidistant dispersion of metal atoms. Therefore, developing a facile method to prepare DACs with both high pairing ratio and tunable distance is essential for advancing the atomic-level understanding of catalytic mechanisms and expanding the repertoire of atomically dispersed metal catalysts.\u003c/p\u003e \u003cp\u003eIn this work, we introduce a ligand-restricted synthesis strategy for achieving highly pairing homo- and heteronuclear DACs with controllable distances engineered by coordinating diamine ligands with two metal precursors on two-dimensional (2D) graphitic carbon nitride (g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e). Our engineered DACs achieve a pairing ratio exceeding 82%, which markedly surpassing previously reported values. Furthermore, we demonstrate the ability to control atomic distances from 0.47 to 0.22 nm by varying the chain length of diamine ligands\u0026mdash;a capability not realized by existing methods. As a proof of concept, the pairing atom Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA DACs exhibited considerably higher catalytic activity (744 mg h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e mg\u003csub\u003emetal\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e) than the unpairing counterpart (255 mg h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e mg\u003csub\u003emetal\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e) in nitrate reduction to ammonia. Furthermore, shorter distanced Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e DAC reveals higher activity than longer ones in photothermal catalyzed hydrogenation reactions. Our strategy could be used to prepare various homo and heteronuclear Pt-, Au- based DACs. This work not only presents a novel synthesis strategy for the atomic-level manufacturing of complex catalysts but also provides valuable insights into nanoscale reactions in heterogeneous catalysis.\u003c/p\u003e"},{"header":"2. Results and discussion","content":"\u003cp\u003e \u003cb\u003eStructural characterization of pairing DACs\u003c/b\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea shows the proposed ligand-restricted strategy for synthesizing highly pairing homo/heteronuclear DACs on g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e. Linear 1,6-hexanediamine (HA) was used as the ligand with two amine groups to coordinate the two metal precursors. Owing to its abundant N sites and defects, 2D g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e was employed as the support.\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e For homonuclear Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA DACs, one HA molecule could restrict two Pt atoms by forming Pt-HA compounds via dechloriantion (which will be discussed later), which are then adsorbed on the 2D g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e support by electrostatic interaction. Pt loading is approximately 0.45 wt% based on inductively coupled plasma optical emission spectrometry (ICP-OES) analysis. The X-ray diffraction (XRD) pattern of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e showed two well-resolved peaks at 13\u0026deg; and 27.4\u0026deg; (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e), which can be indexed as the (100) and (002) of the in-plane structural packing motif of tri-s-triazine units and interlayer stacking of aromatic segments, respectively.\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e,\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e The absence of additional diffraction peaks in the XRD pattern after Pt loading indicated no agglomerated Pt particles. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) was performed on Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA to characterize the of Pt atom dispersion status. Numerous bright dots representing the Pt atoms were observed (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb-d and S2a-d). Importantly, many pairing Pt atoms were easily distinguished and are highlighted by white circles in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee further displays the magnified corresponding three-dimensional (3D) atom-overlapping Gaussian-function fitting mapping of the area marked by the yellow rectangular box in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec. The pairing feature for Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA was clearly shown. In contrast, for the control sample without the HA ligand in Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none, Pt atoms were randomly dispersed on g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e with aggregated Pt atoms or sporadically isolated Pt atoms (Figures S2e-h). These findings indicated that HA could restrict the free-moving behavior of Pt atoms in solution and on support by pairing them with two Pt precursors. Thermal treatment conditions on catalysts directly influence the metal dispersion state. When the pyrolysis temperature was increased from 300 \u003csup\u003eo\u003c/sup\u003eC to 400 \u003csup\u003eo\u003c/sup\u003eC, a large number of Pt particles, rather than single atoms, were observed on Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA-400 (Figure S3), indicating that the metal-support interactions at higher temperatures are insufficient to anchor and disperse Pt atoms, resulting in aggregation with stronger metal-metal interactions. In fact, this interaction varies across metals. Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA was dispersed as Pt atomic pairs after calcination at 300 \u003csup\u003eo\u003c/sup\u003eC. Under the same conditions, Au\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA showed numerous Au particles coexisting with Au single/dual atoms (Figure S4). This suggests that the Pt-support interaction dominates the Pt-Pt interaction, while the Au-Au interaction dominates the Au-support interaction. Metal-metal and metal-support interactions are opposite, responsible for metal agglomeration and dispersion,\u003csup\u003e\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e respectively. To obtain atomically dispersed species, it is necessary to fulfill the reaction condition that the metal-support interaction should be stronger than the metal-metal interaction to obtain atomically dispersed species.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eUnlike homonuclear DACs, the design of heteronuclear DACs requires to the sequential introduction of two different metals near the anchor or defect sites of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e. Therefore, Pt single atoms that have strong metal-support interactions are first fixed on the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e surface by Pt-N electrostatic interaction. After adding HA ligand, one end amine could coordinate with Pt, and the other end amino group of HA then traps free Au via dechloriantion, finally forming Pt-Au heteronuclear DACs. The weak Au and g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e interaction makes the thermal treatment temperature critical. When it was decreased from 300 \u003csup\u003eo\u003c/sup\u003eC to 200 \u003csup\u003eo\u003c/sup\u003eC, the metal particles were still observed (Figure S5). A further decrease to 150 \u003csup\u003eo\u003c/sup\u003eC caused the particles to disappear, with numerous atoms regularly arranged in pairs throughout the entire region of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef and S6), which are marked by white circles in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg. The absence of Pt and Au diffraction peaks on the XRD pattern implied that no metal particles were formed (Figure S7). The corresponding 3D atom-overlapping Gaussian-function fitting mapping of the yellow rectangular box in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef reveals the presence of atomic pairs in Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eh). To exclude the possibility of mistaking neighboring single atoms for atomic pairs, a region with relatively sparse atoms was selected where clearly defined atomic pairs were identified and found clearly atomic pairs (Figure S8a), indicating that HA has a strong pairing effect for Pt and Au. Owing to the similar atomic sequence and contrast between Pt and Au atoms, minor differences existed for two adjacent atoms in the STEM images and local intensity profiles (Figures S8b and c). Note that the atomic sequence is proportional to brightness in the AC-HAADF-STEM test.\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e,\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e For Pt\u003csub\u003e1\u003c/sub\u003e-Ni\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA DACs synthesized via a similar procedure, Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ei, j\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, and j\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e represent the AC-HAADF-STEM images and the magnified corresponding 3D atom-overlapping Gaussian-function fitting mappings for Pt\u003csub\u003e1\u003c/sub\u003e-Ni\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA. Brightness varies slightly for some atomic pairs. After visualization, two neighboring atoms exhibit two peaks of different heights, where the higher peak represents Pt and the lower peak represents Ni due to the different Z-contrasts of Pt (Z\u0026thinsp;=\u0026thinsp;78) and Ni (Z\u0026thinsp;=\u0026thinsp;28). The suboptimal quality of Pt\u003csub\u003e1\u003c/sub\u003e-Ni\u003csub\u003e1\u003c/sub\u003e DACs compared to Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e DACs presumably may be related to the metal precursor acidity.\u003c/p\u003e \u003cp\u003eThe influence of support materials on the dispersion state of single atoms was also examined. When one-dimensional carbon nanotubes (CNTs) were used as supports, many particles were observed on Pt\u003csub\u003e1\u003c/sub\u003e/CNTs and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/CNTs-HA (Figures S9a and b), implying that Pt and Au atoms are unstable and tend to agglomerate into large particles, probably due to CNTs curvature. In contrast, the 2D graphene oxide (GO) support also produced atomically dispersed Pt and Au (Figures S9c and d). Therefore, 2D materials are more ideal supports for anchoring metal atomic pairing via our strategy.\u003c/p\u003e \u003cp\u003eTo better understand the pairing function of HA, the electron-microscopy-based atom recognition statistics (EMARS) methodology was employed to identify the atomic distances of Pt atoms and to count the atom pairing ratio.\u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e The minimum distance of one atom with its neighboring atoms was counted. The pairing ratio was expressed as the ratio of the number of pairing atoms to the total number of atoms. For homonuclear Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, the pairing ratio is as high as 83%, which far exceeds those of previously reported DACs, as summarized in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ek.\u003csup\u003e\u003cspan additionalcitationids=\"CR18 CR19 CR20 CR21 CR22 CR23 CR24\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e For heteronuclear, Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, the pairing ratio was 82% (Figure S10) using manual statistics. Thus, the high-quality and atomic-level dispersion of dual atoms can be realized by pairing them with the HA ligand.\u003c/p\u003e \u003cp\u003eTo illustrate the generality of our strategy, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea summarizes the relationship of metal dispersion state with metal type, support and thermal treatment temperature after the use of HA ligand based on AC-HAADF-STEM images. For elucidating the pairing mechanism, it is crucial to investigate HA ligand and metal precursor interaction. An FTIR experiment was carried out to characterize the interaction between HA and H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb reveals that N-H and C-N vibrations of HA disappear after H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e and HA were mixed for 30 min, indicating that the terminal amino of HA have successfully bonded with Pt species. In addition, density functional theory (DFT) calculation was performed to delve deeper into the pairing mechanism of HA and Pt in the presence of solvent, including the energies and structures of reaction intermediates, and energy barriers in the corresponding transformation process. DFT results demonstrate that the energy is reduced to -3227.2 Ha after the interaction between H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e and HA, indicating that the combined structure is more stable. Therefore, HA and H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e could spontaneously form a stable Pt-HA compound in water before g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e addition (Figures S11-12), in line with the FTIR results. Dechlorination process between HA and H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e can generate stable bimetallic complexes. For heteronuclear DACs, the HA adsorption behavior on the Pt atom surface is equivalent to the dechlorination process in homonuclear DACs. Therefore, highly pairing homo/heteronuclear DACs can result from HA ligand incorporation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe detailed coordination information of the two Pt atoms in Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA is further explored by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO chemisorption, X-ray absorption near-edge spectroscopy (XANES), and extended X-ray fine-structure spectroscopy (EXAFS) spectra. In the DRIFTS spectrum (Figure S13), almost no notable bridge-CO (~\u0026thinsp;1830 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) or linear-CO (~\u0026thinsp;2090 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) absorption peaks were observed on the Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA sample.\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e,\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e This scenario could be caused by low Pt loading. Therefore, a controlled sample with five-fold Pt loading was synthesized. Despite increasing Pt loading, a bridge-bonded CO adsorption peak remained lacking, indicating the absence of Pt particles. Notably, the CO adsorption peak is asymmetric and is located at around 2060 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e on the Pt dual atom sample, which differs from the CO adsorption peak of the pure single atoms at around 2090 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003csup\u003e51,52\u003c/sup\u003e Therefore, an obviously red shift exists in the linear adsorption of CO by Pt dual atoms in the Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA.\u003csup\u003e53\u003c/sup\u003e Similarly, the Pt L\u003csub\u003e3\u003c/sub\u003e-edge XANES results (Figure S14) indicated Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA had markedly higher white-line intensity than the Pt foil but a lower value than PtO\u003csub\u003e2\u003c/sub\u003e, indicating that the valence state of Pt is between 0 and +\u0026thinsp;4.\u003csup\u003e54,55\u003c/sup\u003e Additionally, the primary peak at 1.60 \u0026Aring; was assigned to Pt-N coordination in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec. The Pt-Pt characteristic peak at 2.60 \u0026Aring; was not detected in the Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA sample, verifying that Pt was almost atomically dispersed in Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA sample instead of clusters or nanoparticles, consistent with the DRIFTS results.\u003c/p\u003e \u003cp\u003ePt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA had a higher white-line intensity than the Pt foil but a lower value than PtO\u003csub\u003e2\u003c/sub\u003e (Figure S15a), suggesting that Pt species carried a partial positive charge (Pt\u003csup\u003eδ+\u003c/sup\u003e, 0\u0026thinsp;\u0026lt;\u0026thinsp;δ\u0026thinsp;\u0026lt;\u0026thinsp;4).\u003csup\u003e54,55\u003c/sup\u003e EXAFS measurement was performed to determine the local structure of the Pt atoms (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). The Pt L\u003csub\u003e3\u003c/sub\u003e-edge EXAFS of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA displayed one peak at 1.60 \u0026Aring; corresponding to the Pt-N contribution. Compared to the Pt foil, the peak at 2.60 \u0026Aring; (Pt-Pt bond) was not detected. This excludes the formation of metallic Pt nanoparticles and confirms the exclusive presence of isolated Pt atoms, in agreement with the AC-HAADF-STEM results. Furthermore, the normalized Au L\u003csub\u003e3\u003c/sub\u003e-edge XANES curves of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA was between the standard of Au foil and Au\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (Figure S15b), indicating the presence of cationic Au species (Au\u003csup\u003eδ+\u003c/sup\u003e, 0\u0026thinsp;\u0026lt;\u0026thinsp;δ\u0026thinsp;\u0026lt;\u0026thinsp;3). The Au L\u003csub\u003e3\u003c/sub\u003e-edge EXAFS curve showed only one main peak at 1.63 \u0026Aring; (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee), attributed to the Au-N scattering path, instead of the Au-Au bond (2.58 \u0026Aring;). Therefore, Au was present as a single atom species in Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, with no evidence of Au-Au bond forming clusters or nanoparticles, implying that HA and g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e successfully captured and immobilized the Au atoms. The fitting of the first shell revealed that Pt-N and Au-N had respective coordination numbers of 4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 and 1.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1. Unlike Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA heated at 300 \u003csup\u003eo\u003c/sup\u003eC, Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA was heated at a lower temperature, so the HA ligand may not be removed. To confirm the presence of HA, we performed a series of attenuated total reflectance infrared experiments on g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e, Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA. The characteristic bands of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e loaded with Pt and Au remained unchanged compared with those of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e. However, some bands at 1250 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e seemed to be covered on Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (Figure S16). Computationally, Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef and g, S17-19 illustrate the electronic structure and adsorption energy of coordinated HA molecule on Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e(-3.88 eV), Pt\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e(-1.09 eV) and Au\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e (-2.75 eV) models, indicating the Pt-Au atomic pair is more favorable to anchor and stabilize HA molecule than Pt and Au single atoms with the electronic interaction. The analysis of the charge density differences of the catalyst models indicates obvious charge transfer between metals and C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e materials. In particular, the Pt atom in Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e had larger electron loss areas (blue region in Figure S19) than Pt\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e, while the Au atom in Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e had smaller areas than that of Au\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e, suggesting electron transferability from Pt to Au atoms via C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e material. Subsequently, to explore the origin of reaction activity, the average Bader charge of different elements was calculated in the pristine C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e, Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e, Pt\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e and Au\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e catalyst surfaces (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). The Bader charge analysis revealed that the C atoms lost average electrons (-1.63 e\u003csup\u003e\u0026minus;\u003c/sup\u003e) and N atoms gained average electrons (+\u0026thinsp;1.22 e\u003csup\u003e\u0026minus;\u003c/sup\u003e) in pristine C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e. After loading Pt and Au in the C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e materials, the C and N atoms tended to gain and lose electrons relative to those of pristine C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e, becoming \u0026minus;\u0026thinsp;1.47 and +\u0026thinsp;1.13 e\u003csup\u003e\u0026minus;\u003c/sup\u003e, respectively. Pt and Au in Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e also lost electrons compared to the corresponding Pt\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e and Au\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e. Hence, we can reasonably infer that the electron transfer order is generally metal site \u0026rarr; N atoms \u0026rarr; C atoms in three catalyst models, leading to a stronger interaction between the electron-rich -NH\u003csub\u003e2\u003c/sub\u003e groups in the HA molecule and the electron-deficient Pt-Au atomic pair in the catalyst of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA. Moreover, the electrons lost in the of metal active site was \u0026minus;\u0026thinsp;0.55 e\u003csup\u003e\u0026minus;\u003c/sup\u003e (Pt site-Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e), \u0026minus;\u0026thinsp;0.45 e\u003csup\u003e\u0026minus;\u003c/sup\u003e (Au site-Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e), \u0026minus;\u0026thinsp;0.36 e\u003csup\u003e\u0026minus;\u003c/sup\u003e (Pt site-Pt\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e), and \u0026minus;\u0026thinsp;0.48 e\u003csup\u003e\u0026minus;\u003c/sup\u003e (Au site-Au\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e), respectively. This finding indicates that the Pt atom can transfer electrons to the Au from the N atoms, consistent with the charge density difference calculation results. Therefore, HA should be stably present on Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA.\u003c/p\u003e \u003cp\u003eTo visually illustrate the Pt or Au coordination environments in Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, the wavelet transform (WT) of the k\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e weighted EXAFS spectras, a reflection of structural information in the resolution of R and K spaces, were conducted (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eh-n). The Pt L\u003csub\u003e3\u003c/sub\u003e-edge EXAFS further confirms the existence of Pt-N rather than Pt-Pt and Pt-O bonds in Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ej) and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ek), respectively. A similar result was observed in Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003en). Therefore, for homonuclear DACs, a bimetallic complex is formed and then loaded onto the support (Figure S20). For heteronuclear DACs, one metal is first fixed on the support and is modified with ligand; finally, the other metal is adsorbed and formed into atom pairs (Figure S21). Although a slight difference exists in the reaction pathway, the principle is based on the dechlorination reaction of HA and metal precursors.\u003c/p\u003e \u003cp\u003e \u003cb\u003eRegulation of the atomic distance of DACs\u003c/b\u003e \u003c/p\u003e \u003cp\u003eInsights from Based the formation mechanism discussed above suggest that the ligand chain length can enable precise adjustment of the atomic distance of DACs. To this end, another ligand molecule, ethylenediamine (EA), was used to replace HA and synthesize DACs, denoted as Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-EA. In addition, a sample without ligand was prepared as the control, denoted as Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none. Lots of pairing bright dots representing Pt atom pairs were easily distinguished from the images of both Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea) and Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-EA (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). For Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none DACs, all Pt atoms showed random and atomic dispersion without formation of Pt pairs (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec), implying that g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e can be used to disperse and anchor metal single atoms, while ligands can be utilized to bind metal atoms in pairs at specific spacings. For a better illustration of the effect of diamine compounds on atomic distance modulation, the sub-\u0026Aring;ngstr\u0026ouml;m accuracy statistical EMASR methodology, \u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e was employed to measure and count the atomic distance between pairing Pt/Au atoms at their nearest neighboring coordination. With a total count of \u0026gt;\u0026thinsp;1950 atoms per sample across all three DACs, the distribution of atomic distance is respectively showed in Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed-f. In general, Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-EA has a shorter atomic distance of 0.22 nm than Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (0.47 nm). These distances are very proportional to the chain lengths of ligands EA (0.46 mn) and HA (10.5 nm).\u003c/p\u003e \u003cp\u003eTo visualize Pt-Pt atomic pairings, atoms with distances of 0-0.33 nm, 0.34\u0026ndash;0.66 nm, 0.67\u0026ndash;0.99 nm and 1.00\u0026ndash;3.00 nm are assigned red, green, blue, and yellow, respectively. Each atom is highlighted with a corresponding colored circle. The color recognition results for Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA and Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none are illustrated in Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg and h, and S22. Clearly, many green circles exist in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg, while many red circles appear in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eh, suggesting that HA efficiently dictates the distance between pairing Pt atoms. In the absence of HA modification, Pt atoms tend to be randomly anchored at abundant sites on g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e. Given that the distance between two adjacent N atoms or defects on g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e is characterized as 0.23 nm, Pt atoms could be anchored at two adjacent sites, either squeezed into the same C\u003csub\u003e6\u003c/sub\u003eN\u003csub\u003e8\u003c/sub\u003e unit cell or separated at two cells (Figure S23). When the Pt precursor is paired with HA or EA, Pt dual atoms are formed with fixed distances (0.47 or 0.22 nm), demonstrating that the ligand size gives precise control over the atomic distances in DACs via our ligand-restricted strategy.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eCatalytic performance of pairing DACs\u003c/b\u003e \u003c/p\u003e \u003cp\u003eAs the experimental results showed, HA molecule modification enabled the effective binding of Pt and Au atoms, so the electrostatic potential (ESP) of HA was analyzed. In Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, the dark blue region, especially around two -NH\u003csub\u003e2\u003c/sub\u003e radicals in HA, presents strong nucleophilic property that obtain more electrons than red regions, which facilitates interaction with metal atoms. Therefore, the catalytic performances of pairing (Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA) and unpairing (Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none) DACs were evaluated via an electrochemical nitrate reduction reaction (NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003eRR). Figures\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, S24 and S25 display the NH\u003csub\u003e3\u003c/sub\u003e yield and Faraday efficiency of different DACs. For highly pairing DACs, Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA exhibited a superior catalytic performance of 744 mg h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e mg\u003csub\u003emetal\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e (i.e., 3347 \u0026micro;g h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) with 95.6% Faraday efficiency. Yet, the NH\u003csub\u003e3\u003c/sub\u003e yield was just 255 mg h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e mg\u003csub\u003emetal\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e on unpairing Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none DACs. Without the Au atom, Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none was inactive, showing a very low NH\u003csub\u003e3\u003c/sub\u003e yield. The cycling stability of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA was investigated by performing six successive cycles under optimal reaction conditions. The NH\u003csub\u003e3\u003c/sub\u003e yield and Faraday efficiency foscillated within a small range but generally remained stable (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec). The NH\u003csub\u003e3\u003c/sub\u003e yield decreased slightly after the second cycle. The Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA also exhibited favorable stability without a notable decrease in NH\u003csub\u003e3\u003c/sub\u003e yield during the long-term electrolysis test for 15 h (Figure S26). These results imply that increasing the pairing ratio of DACs can markedly enhance the catalytic activity in NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003eRR.\u003c/p\u003e \u003cp\u003eTo further investigate the relationship between electronic structures and the NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003eRR performance of the Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA catalyst, all possible reaction mechanisms were proposed and calculated by the DFT simulations (Figures S27-29). For Pt\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e and Au\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e models, the potential-determining-step (PDS) with the highest Gibbs free energy change (∆\u003cem\u003eG\u003c/em\u003e) were the protonation reactions of *NO\u0026thinsp;+\u0026thinsp;H\u003csup\u003e+\u003c/sup\u003e + e\u003csup\u003e\u0026minus;\u003c/sup\u003e \u0026rarr; *NHO and *NO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;H\u003csup\u003e+\u003c/sup\u003e + e\u003csup\u003e\u0026minus;\u003c/sup\u003e \u0026rarr; *NO\u003csub\u003e3\u003c/sub\u003eH, respectively, with ∆\u003cem\u003eG\u003c/em\u003e in PDS of 0.68 and 1.00 eV (Figures S30-37). However, for Pt\u003csub\u003e1\u003c/sub\u003eAu\u003csub\u003e1\u003c/sub\u003e/C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e, *NO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;H\u003csup\u003e+\u003c/sup\u003e + e\u003csup\u003e\u0026minus;\u003c/sup\u003e \u0026rarr; *NO\u003csub\u003e3\u003c/sub\u003eH could occur on the Pt site, after which *NO\u003csub\u003e2\u003c/sub\u003e spontaneously transferred to the Au site with an exothermicity of 0.21 eV. The new PDS was *NO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;H\u003csup\u003e+\u003c/sup\u003e + e\u003csup\u003e\u0026minus;\u003c/sup\u003e \u0026rarr; *NO\u003csub\u003e2\u003c/sub\u003eH, with a ∆\u003cem\u003eG\u003c/em\u003e of 0.43 eV (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed). Therefore, for heteronuclear DACs, a higher pairing ratio means a more desirable synergy between the two metal active sites, which maximizes the catalytic potential of DACs.\u003c/p\u003e \u003cp\u003eIn addition, regulating atomic distance is also important and advanced for investigating the catalytic performance over atomically dispersed catalyst. Since Au features localized surface plasmon resonance (LSPR), another probe reaction (i.e., the photothermal selective hydrogenation of phenylacetylene) was carried out on Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-EA to study the effect of atomic distance on catalytic performance. The activity results show that the activity of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-EA is about 4-fold higher than that of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA (Figures S37a, b), implying that the contribution of LSPR is more pronounced at closer atomic distances and favors higher catalytic activity in photothermal selective hydrogenation of phenylacetylene. Therefore, regulating atomic distance is important and advanced for atomic-level designing and investigating highly efficient catalyst.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"3. Conclusion","content":"\u003cp\u003eThrough experiments and theoretical analyses conducted, we have demonstrated that the developed ligand-restricted strategy can effectively fabricate highly paired homonuclear and heteronuclear DACs. Leveraging the efficient electrostatic coordination interaction between metal atoms and the nucleophilic nitrogen atoms of diamine ligands and 2D supports, the pairing ratio achieved exceeded 82%, significantly outperforming previously reported DACs. By modulating the ligand size, precise control over atomic distances in DACs was achieved, ranging from 0.47 to 0.22 nm. As a model system, the highly pairing Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA exhibited around three times catalytic activity (744 mg h⁻\u0026sup1; mgₘₑₜₐₗ⁻\u0026sup1;) in NO₃\u003csup\u003e\u0026minus;\u003c/sup\u003eRR, far surpassing the performance of the unpaired Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none (255 mg h⁻\u0026sup1; mgₘₑₜₐₗ⁻\u0026sup1;). This enhanced activity is attributed to high-quality two-site synergistic catalysis. Furthermore, shorter distanced Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-EA exhibited higher activity than Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA in photothermal catalyzed hydrogenation reactions. Our strategy could be used to prepare various homo and heteronuclear Pt-, Au- based DACs. This study introduces a novel design strategy for the precise and efficient control of metal dispersion at the atomic level, offering both accessibility and practicality for advanced catalytic applications.\u003c/p\u003e"},{"header":"4. Experimental section","content":"\u003cp\u003e \u003cb\u003eSynthesis of g-C\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eN\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e. Typically, 30 g urea was placed in an alumina crucible and calcined to 550\u0026deg;C at a rate of 5\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and kept for 4 h in a static air atmosphere, which was then cooled down to room temperature to obtain a light-yellow powder denoted as g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of homonuclear Pt\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e/g-C\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eN\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-HA DACs and Au\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e/g-C\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eN\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-HA samples.\u003c/b\u003e To synthesize Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, 0.1 M H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO aqueous solution was added to 20 mL of water, followed by adding 0.1 M HA aqueous solution with a Pt:N molar ratio of 1:1 under magnetic stirring for 30 min. Subsequently, 400 mg of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e powders was dispersed in the above mixture and kept stirring for another 24 h. After that, the suspension was heated at 80 \u003csup\u003eo\u003c/sup\u003eC to remove water. The obtained material was dried at 60\u0026deg;C overnight, then calcined in N\u003csub\u003e2\u003c/sub\u003e at 300\u0026deg;C for 2 h with a heating rate of 5\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The final product was denoted as Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA. The calcination temperature increased to 400\u0026deg;C to get Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA-400. Correspondently, Au\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA samples was synthesized via a similar procedure to that of Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA except that H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO was replaced with HAuCl\u003csub\u003e4\u003c/sub\u003e\u0026middot;4H\u003csub\u003e2\u003c/sub\u003eO. As a control, Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none was also prepared in a similar procedure described above without adding HA. Pt\u003csub\u003e2\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA was prepared by EA instead of HA ligand.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of heteronuclear Pt\u003c/b\u003e \u003csub\u003e \u003cb\u003e1\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-Au\u003c/b\u003e \u003csub\u003e \u003cb\u003e1\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e/g-C\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eN\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-HA DACs.\u003c/b\u003e Typically, 120 \u0026micro;L of 0.1 M H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e6\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO aqueous solution was added to 120 mL of water under constant stirring to get a homogeneous solution. Then, 400 mg of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e was added to the above solution with continuous stirring for 24 h. After that, the above mixture was heated at 80 \u003csup\u003eo\u003c/sup\u003eC to remove water solvent, dried at 60\u0026deg;C overnight, and then calcinated in N\u003csub\u003e2\u003c/sub\u003e at 300\u0026deg;C for 2 h with a heating rate of 5\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. It is notable that periodic triangular defects of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e serving as ideal anchor sites could enable dispersion of pioneering Pt at atomic scale by facile wetness impregnation. Next, as-prepared Pt\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e SACs was subjected to decoration procedure prior to invite the second atom. Specifically, 300 mg of Pt\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e SACs was dispersed to 15 mL of water with agitated stirring. Then, 75.6 \u0026micro;L of 0.1 M HA aqueous solution was dropped into the above suspension. After stirred for 1 h, 15 \u0026micro;L of 0.1 M HAuCl\u003csub\u003e4\u003c/sub\u003e\u0026middot;4H\u003csub\u003e2\u003c/sub\u003eO aqueous solution was introduced into the above-resulting mixture and stirred for another 23 h. After completely evaporated at 80\u0026deg;C and dried overnight, the collected material was calcined under N\u003csub\u003e2\u003c/sub\u003e at 150 \u003csup\u003eo\u003c/sup\u003eC or 200 \u003csup\u003eo\u003c/sup\u003eC for 1 h with a heating rate of 5\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to obtain the final product denoted as Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA-200, respectively. For comparison, Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/CNTs-HA and Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/GO-HA were prepared in a similar process except that the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e was replaced by CNTs and GO, respectively. Furthermore, Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-none was also constructed based on the above typical preparation strategy without adding HA.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of heteronuclear Pt\u003c/b\u003e \u003csub\u003e \u003cb\u003e1\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-Ni\u003c/b\u003e \u003csub\u003e \u003cb\u003e1\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e/g-C\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eN\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-HA DACs.\u003c/b\u003e The synthesis procedure of Pt\u003csub\u003e1\u003c/sub\u003e-Ni\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA was similar to that of Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-HA, except that HAuCl\u003csub\u003e4\u003c/sub\u003e\u0026middot;4H\u003csub\u003e2\u003c/sub\u003eO aqueous solution was replaced by 8.7 mg NiCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO.\u003c/p\u003e \u003cp\u003e \u003cb\u003eElectrocatalytic nitrate reduction.\u003c/b\u003e All electrochemical measurements were carried out at room temperature in a typical H-type cell, which is separated into two chambers by a Nafion 211 membrane. A CHI 760E electrochemical workstation electrochemical was used to control the electrolysis reaction. The Hg/HgO reference electrode and the working electrode were placed in the cathode chamber, while the platinum plates (2 cm \u0026times; 2 cm) counter electrode was placed in the anode chamber. The working electrode was prepared as follows: 6 mg samples, 960 \u0026micro;L ethanol, and 40 \u0026micro;L Nafion solution (5 wt%) were mixed and ultra-sonicated for 1 h to get a homogeneous catalyst ink. Then, a proper volume of ink was dropped onto carbon paper with a loading of 0.5 mg cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. 0.1 M KOH electrolyte (60 mL, pH\u0026thinsp;=\u0026thinsp;13.1) was equally distributed to the anode and cathode chambers. This alkaline electrolyte can not only inhibit the side HER, but also facilitates the migration and activation of NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e. On the other hand, the potentials in this study were converted to the reversible hydrogen electrode (RHE) potential: E\u003csub\u003eRHE\u003c/sub\u003e= E\u003csub\u003eHg/HgO\u003c/sub\u003e+0.098 V\u0026thinsp;+\u0026thinsp;0.059 pH. Therefore, the slight fluctuation of the pH of the alkaline electrolyte during the reaction has little effect on the working potential. The size of the working electrode immersed in electrolyte is 1 \u0026times; 1 cm\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. For the electrochemical NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003eRR, KNO\u003csub\u003e3\u003c/sub\u003e was added to the cathode electrolyte (containing 7.14 mM NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e). During the reaction, a high-purity argon flow (10 mL min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) was continuously injected into the cathode cell, and the electrolyte was stirred at a rate of 200 rpm. NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003eRR experiments were carried out at different potentials for 1 h to evaluate the performance of the catalyst. The linear sweep voltammetry (LSV) was conducted at a rate of 5 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. EIS was performed at \u0026minus;\u0026thinsp;0.2 V vs. RHE from 0.01 to 105 Hz, and the AC amplitude was set to 10 mV. For the stability test, the NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003eRR was carried out at \u0026minus;\u0026thinsp;0.2 V vs. RHE at a stirring rate of 200 rpm. The electrolyte solution was changed every 3 h, and the above experiment was repeated 5 times with the same working electrode. All current densities reported in this work are based on geometric surface area.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFinancial support for this research from the National Natural Science Foundation of China (52033003,\u0026nbsp;22279139, 62227815), the National Key Research and Development Program of China (2022YFA1205200),\u0026nbsp;Program of Higher-level Talents of IMU (10000-23112101/173), Project of Grassland Talent of Inner Mongolia Autonomous Region (12000-12102805) and Natural Science Foundation of Inner Mongolia Autonomous Region of China (20241Q06). The authors thank Dr. Peng-Cheng Chen, Dr. Yue Gu for helpful discussion.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eL.J. and L.W. supervised the project. Y.M. carried out the synthesis, characterization and catalytic measurements and collaborated in writing the manuscript. S.L. and W.L. contributed with\u0026nbsp;EMARS\u0026nbsp;methodology.\u0026nbsp;W.Z., R.Z., K.S. and R.G. performed the DFT calculations and analysis. W.L. carried out the catalytic performance. J.M. and Z.J. performed the XAS measurement and analysed the data. Y.M., Y.Z. and W.L. performed the AC-HAADF-STEM characterization. The paper was written by Y.M., G.L., J.L and L.W. All authors commented on the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSupplementary information is available in the online version of the paper. Reprints and permissions information is available online at www.nature.com/reprints. Correspondence and requests for materials should be addressed to J.L.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting financial interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing financial interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWang A, Li J, Zhang T (2018) Heterogeneous single-atom catalysis. Nat Rev Chem 2:65\u0026ndash;81\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLang R et al (2020) Single-atom catalysts based on the metal-oxide interaction. Chem Rev 120:11986\u0026ndash;12043\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi J, Stephanopoulos MF, Xia Y, Introduction (2020) Heterogeneous single-atom catalysis. Chem Rev 120:11699\u0026ndash;11702\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang S et al (2023) Atomically dispersed bimetallic Fe-Co electrocatalysts for green production of ammonia. Nat Sustain 6:169\u0026ndash;179\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJung E et al (2020) Atomic-level tuning of Co-N-C catalyst for high-performance electrochemical H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e production. Nat Mater 19:436\u0026ndash;442\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang S et al (2023) Fe/Cu diatomic catalysts for electrochemical nitrate reduction to ammonia. Nat Commun 14:3634\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi R, Wang D (2022) Superiority of dual-atom catalysts in electrocatalysis: One step further than single-atom catalysts. Adv Energy Mater 12:2103564\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang F et al (2022) Low-temperature acetylene semi-hydrogenation over the Pd\u003csub\u003e1\u003c/sub\u003e-Cu\u003csub\u003e1\u003c/sub\u003e dual-atom catalyst. J Am Chem Soc 144:18485\u0026ndash;18493\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMa YF, Wang LW, Liu J (2022) Single atom catalysts in liquid phase selective hydrogenations. Chem Res Chin Univ 38:1163\u0026ndash;1171\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWei X et al (2021) Cu acting as Fe activity promoter in dual-atom Cu/Fe-NC catalyst in CO2RR to C1 products. Appl Surf Sci 564:150423\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang X-M, Wang H-J, Zhang C, Zhong D-C, Lu T-B (2023) Controlled synthesis of a Ni\u003csub\u003e2\u003c/sub\u003e dual-atom catalyst for synergistic CO\u003csub\u003e2\u003c/sub\u003e electroreduction. Appl Catal B 322:122073\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJiao J et al (2019) Copper atom-pair catalyst anchored on alloy nanowires for selective and efficient electrochemical reduction of CO\u003csub\u003e2\u003c/sub\u003e. Nat Chem 11:222\u0026ndash;228\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi R, Wang D (2022) Understanding the structure-performance relationship of active sites at atomic scale. Nano Res 15:6888\u0026ndash;6923\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu M et al (2024) Cascade Synthesis of Fe-N\u003csub\u003e2\u003c/sub\u003e-Fe Dual-Atom Catalysts for Superior Oxygen Catalysis. Angew Chem Int Ed 63:e202408914\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang W et al (2021) Emerging dual-atomic-site catalysts for efficient energy catalysis. Adv Mater 33:2102576\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen Y et al (2023) Inter-metal interaction of dual-atom catalysts in heterogeneous catalysis. Angew Chem Int Ed 62:e202306469\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWei YS et al (2020) Fabricating dual-atom iron catalysts for efficient oxygen evolution reaction: A heteroatom modulator approach. Angew Chem Int Ed 132:2\u0026ndash;11\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLu Z et al (2019) An isolated zinc-cobalt atomic pair for highly active and durable oxygen reduction. Angew Chem Int Ed 58:2622\u0026ndash;2626\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDing T et al (2021) Atomically precise dinuclear site active toward electrocatalytic CO\u003csub\u003e2\u003c/sub\u003e reduction. J Am Chem Soc 143:11317\u0026ndash;11324\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang YX et al (2023) General synthesis of a diatomic catalyst library via a macrocyclic precursor-mediated approach. J Am Chem Soc 145:4819\u0026ndash;4827\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXie P et al (2022) Oxo dicopper anchored on carbon nitride for selective oxidation of methane. Nat Commun 13:1375\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen C et al (2023) Adjacent Fe site boosts electrocatalytic oxygen evolution at Co site in single-atom-catalyst through a dual-metal-site design. Energy Environ Sci 16:1685\u0026ndash;1696\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYu D et al (2021) Dual-sites coordination engineering of single atom catalysts for flexible metal-air batteries. Adv Energy Mater 11:2101242\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang L et al (2023) Enhanced oxygen reduction activity and stability of double-layer nitrogen-doped carbon catalyst with abundant Fe-Co dual-atom sites. Nano Energy 117:108854\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao E et al (2025) Diatomic palladium catalyst for enhanced photocatalytic water-donating transfer hydrogenation. J Am Chem Soc 147:2029\u0026ndash;2036\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang X et al (2020) Confined Fe-Cu clusters as sub-nanometer reactors for efficiently regulating the electrochemical nitrogen reduction reaction. Adv Mater 32:2004382\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGong F et al (2023) Universal sub-nanoreactor strategy for synthesis of yolk-shell MoS\u003csub\u003e2\u003c/sub\u003e supported single atom electrocatalysts toward robust hydrogen evolution reaction. Angew Chem Int Ed 62:e202308091\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLu J (2022) Atomic Lego Catalysts Synthesized by Atomic Layer Deposition. Acc Mater Res 3:358\u0026ndash;368\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYan H et al (2017) Bottom-up precise synthesis of stable platinum dimers on graphene. Nat Commun 8:1070\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYe W et al (2019) Precisely tuning the number of Fe atoms in clusters on N-doped carbon toward acidic oxygen reduction reaction. Chem 5:2865\u0026ndash;2878\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang N et al (2021) A supported Pd\u003csub\u003e2\u003c/sub\u003e dual-atom site catalyst for efficient electrochemical CO\u003csub\u003e2\u003c/sub\u003e reduction. Angew Chem Int Ed 60:13388\u0026ndash;13393\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Y et al (2020) Dual-atom Ag\u003csub\u003e2\u003c/sub\u003e/graphene catalyst for efficient electroreduction of CO\u003csub\u003e2\u003c/sub\u003e to CO. Appl Catal B 268:118747\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTian S et al (2018) Carbon nitride supported Fe\u003csub\u003e2\u003c/sub\u003e cluster catalysts with superior performance for alkene epoxidation. Nat Commun 9:2353\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang J et al (2017) Design of N-coordinated dual-metal sites: A stable and active Pt-free catalyst for acidic oxygen reduction reaction. J Am Chem Soc 139:17281\u0026ndash;17284\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang J et al (2018) Synergistic effect of well-defined dual sites boosting the oxygen reduction reaction. Energy Environ Sci 11:3375\u0026ndash;3379\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRen W et al (2019) Isolated diatomic Ni-Fe metal-nitrogen sites for synergistic electroreduction of CO\u003csub\u003e2\u003c/sub\u003e. Angew Chem Int Ed 58:6972\u0026ndash;6976\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTang T et al (2023) Dual-atom Co-Fe catalysts for oxygen reduction reaction. Chin J Catal 46:48\u0026ndash;55\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHan X et al (2019) Atomically dispersed binary Co-Ni sites in nitrogen-doped hollow carbon nanocubes for reversible oxygen reduction and evolution. Adv Mater 31:1905622\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi WH, Yang J, Wang D (2022) Long-range interactions in diatomic catalysts boosting electrocatalysis. Angew Chem Int Ed 61:e202213318\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMeng X et al (2020) Distance synergy of MoS\u003csub\u003e2\u003c/sub\u003e-confined rhodium atoms for highly efficient hydrogen evolution. Angew Chem Int Ed 132:10588\u0026ndash;10593\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJiang S et al (2024) Visualization of the distance-dependent synergistic interaction in heterogeneous dual-site catalysis. J Am Chem Soc 146:29084\u0026ndash;29093\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOng WJ, Tan LL, Ng YH, Yong ST, Chai SP (2016) Graphitic carbon nitride (g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e)-based photocatalysts for artificial photosynthesis and environmental remediation: Are we a step closer to achieving sustainability? Chem Rev 116:7159\u0026ndash;7329\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTian X et al (2019) Surface P atom grafting of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e for improved local spatial charge separation and enhanced photocatalytic H\u003csub\u003e2\u003c/sub\u003e production. J Mater Chem A 7:7628\u0026ndash;7635\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang X et al (2016) Facile fabrication of acidified g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e/g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e hybrids with enhanced photocatalysis performance under visible light irradiation. Appl Catal B 193:22\u0026ndash;35\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTairan, Wang et al (2024) Nature of metal-support interaction for metal catalysts on oxide supports. Science 386:915\u0026ndash;920\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJiao L et al (2021) Non-bonding interaction of neighboring Fe and Ni single-atom pairs on MOF-derived N-doped carbon for enhanced CO\u003csub\u003e2\u003c/sub\u003e electroreduction. J Am Chem Soc 143:19417\u0026ndash;19424\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang B et al (2024) A general metal ion recognition strategy to mediate dual-atomic-site catalysts. J Am Chem Soc 146:24945\u0026ndash;24955\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu S et al (2021) Identify the activity origin of Pt single-atom catalyst via atom-by-atom counting. J Am Chem Soc 143:15243\u0026ndash;15249\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMa YF et al (2019) Tailoring of the proximity of platinum single atoms on CeO\u003csub\u003e2\u003c/sub\u003e using phosphorus boosts the hydrogenation activity. ACS Catal 9:8404\u0026ndash;8412\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCao S et al (2020) High-loading single Pt atom sites Pt-O(OH)(x) catalyze the CO PROX reaction with high activity and selectivity at mild conditions. Sci Adv 6:eaba3809\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDing K et al (2015) Identification of active sites in CO oxidation and water-gas shift over supported Pt catalysts. Science 350:189\u0026ndash;192\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNie L et al (2017) Activation of surface lattice oxygen in single-atom Pt/CeO\u003csub\u003e2\u003c/sub\u003e for low-temperature CO oxidation. Science 358:1419\u0026ndash;1423\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGao R et al (2021) Pt/Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e with Pt-Fe pair sites as a catalyst for oxygen reduction with ultralow Pt loading. Nat Energy 6:614\u0026ndash;623\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang B et al (2016) Stabilizing a platinum1 single-atom catalyst on supported phosphomolybdic acid without compromising hydrogenation activity. Angew Chem Int Ed 55:8319\u0026ndash;8323\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMacino M et al (2019) Tuning of catalytic sites in Pt/TiO\u003csub\u003e2\u003c/sub\u003e catalysts for the chemoselective hydrogenation of 3-nitrostyrene. Nat Catal 2:873\u0026ndash;881\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-5976517/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5976517/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eDual atom catalysts (DACs), characterized by high activity and metal utilization, as well as structural diversity with a large variety of catalytic sites, hold immense promise for energy conversion technologies, garnering substantial interest from both academia and industry. However, achieving precise control and manipulation of atomic dispersion, pairing ratios, and interatomic distances in DACs, which significantly affect their multifunctional catalytic properties, remains a significant challenge. Herein, we developed a ligand-restricted strategy for the precise synthesis of highly pairing DACs with tunable atomic distances. This was accomplished by coordinating diamine ligands with dual metal precursors, restricting the pairing and relative positions of two metal atoms on two-dimensional graphitic carbon nitride. The atomic pairing ratio exceeded 82%, with the chain length of diamine molecules effectively regulating the distance between paired atoms. As a demonstration, the pairing Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e DACs exhibited almost three times catalytic activity for nitrate reduction to ammonia compared to their unpaired counterparts. Furthermore, shorter distanced Pt\u003csub\u003e1\u003c/sub\u003e-Au\u003csub\u003e1\u003c/sub\u003e DAC reveals four times activity in photothermal catalyzed hydrogenation reactions than longer ones. This work not only introduces a novel design strategy for the atomic-scale fabrication of complex catalysts but also provides valuable insights into nanoscale reaction mechanisms in heterogeneous catalysis.\u003c/p\u003e","manuscriptTitle":"Ligand-Restricted Strategy for Synthesizing Highly Pairing Dual Atom Catalysts","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-14 12:08:02","doi":"10.21203/rs.3.rs-5976517/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-materials","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"nmat","sideBox":"Learn more about [Nature Materials](http://www.nature.com/nmat/)","snPcode":"","submissionUrl":"","title":"Nature Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Research","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"353bdff6-4688-41d2-8790-fe32e2305568","owner":[],"postedDate":"February 14th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":44265631,"name":"Physical sciences/Materials science/Nanoscale materials"},{"id":44265632,"name":"Physical sciences/Nanoscience and technology/Nanoscale materials/Two-dimensional materials"}],"tags":[],"updatedAt":"2025-10-27T12:44:04+00:00","versionOfRecord":{"articleIdentity":"rs-5976517","link":"https://doi.org/10.1038/s41563-025-02385-6","journal":{"identity":"nature-materials","isVorOnly":false,"title":"Nature Materials"},"publishedOn":"2025-10-24 04:00:00","publishedOnDateReadable":"October 24th, 2025"},"versionCreatedAt":"2025-02-14 12:08:02","video":"","vorDoi":"10.1038/s41563-025-02385-6","vorDoiUrl":"https://doi.org/10.1038/s41563-025-02385-6","workflowStages":[]},"version":"v1","identity":"rs-5976517","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5976517","identity":"rs-5976517","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}