Transient Pulsed Discharge Preparation of Graphene Aerogel Supported Asymmetric Cu Cluster Catalysts Promote CO2 Reduction to Ethanol

Transient Pulsed Discharge Preparation of Graphene Aerogel Supported Asymmetric Cu Cluster Catalysts Promote CO2 Reduction to Ethanol | 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 Transient Pulsed Discharge Preparation of Graphene Aerogel Supported Asymmetric Cu Cluster Catalysts Promote CO2 Reduction to Ethanol Wenxing Chen, Kaiyuan Liu, Hao Shen, Zhiyi Sun, Qiang Zhou, Guoqiang Liu, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3991307/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 31 Jan, 2025 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Precisely designing asymmetrical structure is an efficient strategy to optimize the performance of metallic catalysts for electrochemical carbon dioxide reduction reactions. Herein, a transient high-density current induced by pulsed discharge is used to rapidly construct graphene aerogel (GAs) supported asymmetric Cu cluster catalysts. Cu atoms decomposed by CuCl 2 are converged on graphene surfaces in GAs together with oxygen originating from the intense current and instantaneous high temperature. The atomic and electronic structures of Cu nanoclusters exhibit asymmetric distribution due to lattice distortion and O-doping in Cu crystals. Typically, in CO 2 reduction reactions, the selectivity and activity of ethanol are related to the asymmetric structure and strong interfacial interaction of Cu-O/C moieties, exhibiting an ideal Faradaic efficiency (ethanol 75.3% and C 2+ products 90.5%) at -1.1 V vs reversible hydrogen electrode (RHE). Meanwhile, the benefit of the strong interaction between Cu nanoclusters and GA supports, the catalyst exhibits long-term stability. In situ XAFS reveals that the Cu 4 -Cu/C 2 O 1 interaction displays the effective active sites in CO 2 RR. The pathways of corresponding products and the reaction mechanism on Cu 4 -Cu/C 2 O 1 moieties are revealed through the in situ attenuated total reflectance Fourier transform infrared spectroscopy and the calculation of density functional theory. This work gives a new solution to solve the challenge for balancing the activity and stability of asymmetric-structure catalysts toward energy conversion reactions. Physical sciences/Chemistry/Catalysis/Electrocatalysis Physical sciences/Energy science and technology/Carbon capture and storage Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction The electrochemical catalytic carbon dioxide reduction reaction (CO 2 RR) driven by renewable electricity provides a green solution for energy and environmental crises 1, 2 . Multi-carbon compounds (C 2+ ), such as ethylene, ethanol, and propanol, have higher accessional value compared to single-carbon organic products (C 1 ) 3, 4 . Among them, ethanol (EtOH) is considered an outstanding liquid fuel and industrial chemical owing to its significant energy density and wide range of applications 5–7 . Besides, EtOH also possesses the advantages of long-term storage, ease of transportation, and scalability 8, 9 . Recently, multiple investigations have demonstrated that copper-based catalysts feature a highly efficient conversion from carbon dioxide to C 2+ products, with high selectivity. However, their selectivity and current density for producing EtOH are still under improvement 10–12 . Nano metals or metal oxides supported-type catalysts feature plenty of nano heterostructures consisting of metal atoms and adjacent coordination species on the support, whose precisely adjustable structure advantages the design of efficient nanocatalysts 13–15 . The carbon-supported nano Cu or CuO x catalysts rely on the absorption features of the *CO and *H on the Cu atoms, these catalysts could enhance their selectivity of C 2+ products and EtOH 16, 17 . Furthermore, related researches have revealed that their low coordination Cu atoms in Cu nanoparticles are the source of CO 2 RR catalytic active sites 18, 19 . The decreasing size of metal nanoparticles increases the specific surface of the metal with more active atoms, enhancing the catalytic activity 20–22 . Consequently, the metal clusters (< 2 nm) feature outstanding catalytic performance compared to the corresponding metal nanoparticles 23–25 . Additionally, optimizing the local structure and coordination of carbon-supported copper cluster catalysts can further enhance the catalytic activity of copper clusters by regulating the interaction between active sites and supports 26, 27 . The adjustment of cluster dispersion on the support is one efficient route to optimize the local structure which could change the electronic state of active sites, and affect the reaction pathway with different catalytic mechanism 28, 29 . However, the multi-step synthetic pathway from CO 2 RR to ethanol could lead to the high energy barrier and complex mechanism of the C-C coupling process. Thus, it is still a significant challenge for designing catalysts with clear active sites 30–32 to investigate the action of active sites in the EtOH production process of CO 2 RR and the structure-activity relationship in electrochemical catalytic reactions. The delicate design of Cu nanoclusters on carbon matrix can significantly enhance the catalytic efficiency 33–35 . Meanwhile, the customization of accurate metal-support coordination structures contributes to the study of structure-activity relationships 36 . Researchers have utilized various strategies to synthesize designed metal cluster/carbon matrix specimens 37–41 for further investigation on the electrochemical catalytic reactions. Herein, novel graphene aerogels support Cu nanocluster catalysts (Cu Clu/GAs) with Cu 4 -CuC 2 O 1 atomic interaction structures and outstanding properties are prepared by a pulsed discharge strategy efficiently. The size of nano coppers on GA can be modulated from 1.4 nm to 7.5 nm by pulsed discharge conditions. Impressively, the Cu Clu/GAs exhibit excellent selectivity and activity in CO 2 RR to produce EtOH. Moreover, they propose a long-term stability (> 60 h). The Cu Clu/GAs with asymmetric distribution of atomic and electronic coordination structures are confirmed through atomic-level structural analysis. In situ X-ray absorption fine structure (XAFS) measurements for Cu Clu/GA demonstrate that the asymmetric Cu 4 -CuC 2 O 1 moieties could promote the EtOH production in the electrocatalytic CO 2 RR process. The main intermediates are detected by in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FITR) test. The pathways of CO 2 RR on Cu 4 -CuC 2 O 1 are figured out by the calculation of density functional theory (DFT). Additionally, other metal clusters supported by GAs (M Clu/GAs, M = Fe, Co, Pt, Ru) with asymmetric structures could be synthesized by similar pulsed discharge processes. Results and discussion Synthesis and morphology characterizations of Cu Clu/GAs. Graphene hydrogel (GH) could be prepared by the hydrothermal assembly method 41 . The graphene oxide solvent was poured into a glass bottle with an inner diameter of 15 mm and a depth of 25 mm. The copper chloride was added to the suspension to form a certain concentration of CuCl 2 solvent. The GH was immersed in the CuCl 2 solvent for 5 hours. Then the beaker including GH and solvent were frozen using liquid nitrogen. During the frozen vacuum drying process, the ice sublimated and the CuCl 2 nano-crystals were separated on the surface of graphene aerogel (GA, Supplementary Fig. 1). Then the GA in size of Φ9×15 mm was fabricated (with CuCl 2 5 wt%). The content of CuCl 2 can be modified by the mass of CuCl 2 in the bottle. The CuCl 2 /GAs were compressed into the copper tube by copper plugs. Subsequently, the tube was fixed with two electrodes for discharge (Supplementary Figs. 2 and 3). After the charging of the capacitor, the air switch was triggered for pulsed discharge. The CuCl 2 would be decomposed into Cu and chlorine (Cl 2 ) rapidly in the discharge tube due to the transient Joule heating. After pulsed discharge, the decomposed Cu atoms converged to form Cu clusters on the GAs during a rapid cooling process to form Cu Clu/GA specimens. Figure 1 a presents the formation schematic diagram of Cu Clu/GA. A presentative discharge current waveform in the copper discharge tube containing a CuCl 2 /GA is shown in Fig. 1 b and Supplementary Fig. 4, revealing the typical current-voltage (I-U) waveforms in the resistance-inductance-capacitance (RLC) circuit during the pulsed discharge. Figure 1 c is the photo of Cu Clu/GA on a flower, presenting its extremely low density. Carbon-based supports loaded metal nanocluster catalysts could be rapidly synthesized under the transient pulsed discharge technology (Supplementary Fig. 5). Especially, the I-U curves indicate that the resistance of the circuit did not change during the pulsed discharge process, implying that the GA support was no decomposition and phase change after the transient pulsed discharge treatment, as evidenced in the recovered intact GA after pulsed discharge. Moreover, the intense current pulse can generate an intense electromagnetic field and induce multiple transient high temperature zones on GA. Meanwhile, the CuCl 2 nano-crystals in GA decomposed to form Cu 2+ and *Cl ions under the action of high temperature. These ions burst out and agglomerate to form clusters anchoring on the GA support during pulsed discharge, due to the action of the intense pulsed electromagnetic field in the copper tube. In addition, the air in the porous GA may form multiple local corona discharge plasma, consisting of O ions and N ions, and may form strong atomic interactions between metal clusters and GA support. Moreover, during the pulsed discharge process, the magnetic pinch effect caused by the dynamic electromagnetic field inhibits the radial expansion of the formed ions 42 , which maintain a relatively high-density plasma including Cu, and O ions in GA. Consequently, the mixed Cu and O ions agglomerate to form clusters on the defects of graphene. Cu clusters/nanoparticles of various sizes (1.4 nm, 1.7 nm, 2.7 nm, 4.1 nm, and 7.5 nm) were rapidly synthesized and securely anchored onto graphene by adjusting the charging voltage to increase the pulsed discharge duration. They are identified as Cu 1.4 Clu/GAs, Cu 1.7 Clu/GAs, Cu 2.7 NPs/GAs, Cu 4.1 NPs/GAs, and Cu 7.5 NPs/GAs, respectively (Supplementary Figs. 6–10). The results in Supplementary Table 1 indicate that inputting higher energy in a shorter time would result in the formation of smaller Cu nanoparticles on GAs. The 3D porous structure of Cu 1.7 Clu/GA is also performed by scanning electron microscope (SEM), and many clusters are distributed on graphene by the transmission electron microscopy (TEM) (Supplementary Fig. 7). Figure 1 d shows the mapping energy dispersive spectrum of Cu 1.7 Clu/GAs, where the carbon (C), oxygen (O), Cu elements are uniformly distributed in the reduced graphene oxide (r-GO). The energy dispersive spectrometer (EDS) mapping results displayed the Cu atoms content of approximately 1.83 at%. Figure 1 e presents a high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of Cu 1.7 Clu/GAs, plenty of clusters were dispersed onto the graphene. Uniformly sized Cu clusters were so evenly seeded on graphene because the instantaneous characteristics of pulsed discharge inhibit the continued growth of these Cu clusters. Figure 1 f shows the higher magnification HAADF-STEM image of Cu 1.7 Clu/GAs, and some local crystal plane spacing could be measured, while the Cu 2 O crystal features were identified. Nanoclusters exhibit severe lattice distortion, which is due to the thermal effect and electromigration coupling effect generated by high-frequency pulsed discharge, resulting in atomic diffusion at different speeds in different directions. Meanwhile, Cu nanoclusters are highly susceptible to oxidation due to their high specific surface energy. Subsequently, the diameters of these nanoclusters were counted by the Nanomeasure software, and the distribution of frequency-diameter was shown in Fig. 1 g. It can be seen that the diameters range is from 1.2 nm to 2.6 nm, and the proportion of nanoclusters with a diameter of 1.5 nm is the highest (~ 30%), and the average diameter is 1.7 nm. Electrocatalytic characterizations. The electrocatalytic CO 2 RR performance of Cu 1.4 Clu/GAs, Cu 1.7 Clu/GAs, Cu 2.7 NP/GAs, Cu 4.1 NP/GAs, and Cu 7.5 NP/GAs was evaluated by an H-type cell (Supplementary Fig. 11). Linear sweep voltammetry (LSV) plots (Fig. 2 a) are employed to acquire polarisation curves in the CO 2 -saturated 0.5 M KHCO 3 aqueous solution. Moreover, the activity of Cu 1.7 Clu/GAs exhibited the lowest onset potential and the fastest decreasing current density in all samples. The FEs of EtOH (FEs EtOH ) were obtained at different potentials (from − 0.8 V to -1.2 V) for Cu 1.7 Clu/GAs and Cu 7.5 NP/GAs, as shown in Fig. 2 b. Impressively, the FE EtOH of Cu 1.7 Clu/GAs reached 75.3% at -1.1 V, while the FEs EtOH of other samples (Supplementary Fig. 12) remained at the relatively lower level in the wide potential range. Furthermore, the FEs EtOH of Cu 1.7 Clu/GAs could be maintained > 55% at -0.9 V to -1.2 V, exhibiting outstanding selectivity on EtOH production from CO 2 RR, which was better than the performances of Cu 2.7 NPs/GAs, Cu 4.1 NPs/GAs, and Cu 7.5 NPs/GAs. Moreover, the local current densities of EtOH (J EtOH ) of Cu 1.7 Clu/GAs were calculated (Fig. 2 c) from − 0.8 V to -1.2 V, and the optimal J EtOH was − 33.5 mA cm − 2 at -1.1 V. The current densities of other samples were weaker than that of Cu 1.7 Clu/GAs at the potential range. Impressively, the performance of Cu 1.7 Clu/GAs exceeded the most listed electrochemical catalysts on CO 2 RR-to-EtOH in recent literature (Supplementary Fig. 13 and Supplementary Table 2). Figure 2 d provides the FEs of various products on Cu 1.7 Clu/GAs at the operated potential from − 0.6 V to -1.2 V vs. RHE. The main products were H 2 and CO at the higher potentials (-0.6 V and − 0.7 V), and the product of EtOH was first detected when the potential decreased to -0.8 V (Supplementary Table 3), EtOH dominated at lower potentials (from − 0.9 V to -1.2 V). Meanwhile, the FEs of C 1 , and C 2+ , H 2 , were counted and presented in Supplementary Fig. 14, and FE C2+ reached a surprising 90.5%. Additionally, the CO 2 RR performance of Cu 1.4 Clu/GAs at different potentials was provided in Supplementary Fig. 12 and Supplementary Table 4, the FE EtOH reached a decent 66.5% at -0.9 V. The long-term stability of CO 2 RR is crucial and the potential issue of metal dissolution should not be overlooked. The stability measurement results of Cu 1.7 Clu/GAs are shown in Fig. 2 e, the FE EtOH of Cu 1.7 Clu/GAs keep on > 74% with a negligible current density loss at the operated potential of -1.1 V during the 60 h stability measurement. At the same time, all the J EtOH remain below − 33.0 mA cm − 2 from beginning to end. These indicate that Cu 1.7 Clu/GAs possess excellent stability in the electrocatalytic CO 2 RR process. The comprehensive performance of Cu 1.7 Clu/GAs is evaluated in the electrochemical catalytic CO 2 RR process, as shown in Fig. 2 f. Compared to Cu/N 0.14 C 36 and Cu 1.4 Clu/GAs, the Cu 1.7 Clu/GAs is the most versatile. The CO 2 RR performance of Cu 1.7 Clu/GAs in a flow cell (Fig. 2 g) was conducted, and the result is presented in Fig. 2 h and Supplementary Fig. 15. The FE EtOH and J EtOH reached 68.7% and − 343.8 mA cm − 2 at -1.1 V vs. RHE respectively, which were competitive compared to previous report (Supplementary Table 2). Furthermore, the stability measurement manifested that the loss of applied potential and FE EtOH were ignorable at -343.8 mA cm − 2 for Cu 1.7 Clu/GAs. The impressive activity, selectivity, and stability of Cu 1.7 Clu/GAs make it a promising candidate for practical electrode applications in electrocatalytic CO 2 RR for EtOH production. Atomic coordination structure and chemical state analysis of Cu 1.7 Clu/GAs. Figure 3 a illustrates the high-resolution Cu 2p XPS spectra of Cu 1.7 Clu/GAs and Cu 1.4 Clu/GAs. Two main peaks at 953.4 eV (Cu 2p 1/2 ) and 933.6 eV (Cu 2p 3/2 ) were usually allocated to either Cu 0 or Cu + 43 in Cu 1.7 Clu/GAs. C 1s XPS spectrum of Cu 1.7 Clu/GAs and Cu 1.4 Clu/GAs present an additional peak at 282.9 eV corresponding to the Cu-C bond (Fig. 3 b and Supplementary Fig. 16c), which implies the effect of strong oxide-support interaction existed possibly between Cu 2 O/CuO clusters and GAs 44, 45 . The oxygen content is highest in Cu 1.4 Clu/GAs, second in Cu 1.7 Clu/GAs, and lowest in GAs (Supplementary Figs. 16–18), indicating that additional oxygen is introduced from the atmosphere during the process of pulsed discharge synthesis of Cu Clu/GAs. X-ray diffraction (XRD) reveals a broad peak from the (002) of the GAs (Supplementary Fig. 19), the weak peaks of Cu were displayed in Cu 7.5 NPs/GAs. However, no diffraction peaks corresponding to Cu 2 O crystals were detected in Cu 1.7 Clu/GAs, which indicates that the size of the Cu 2 O clusters may be below the detection limit 46 . Raman spectroscopy was further employed to study the defect on GAs, two significant peaks at 1343 cm − 1 and 1585 cm − 1 represent the characteristics of graphene (Supplementary Fig. 20). The value of I D /I G increased to 1.19 from 1.09, indicating an increase in defects in graphene after the transient pulsed discharge. Combined with the analysis of XPS results, the formation of C-Cu bonds and the entry of oxygen atoms in the Cu Clu/GAs may be the main reasons for the increase of I D /I G . X-ray absorption spectroscopy (XAS) was utilized to further study the geometric and electronic structure of Cu Clu/GAs. The C K-edge absorption spectrum of GAs, Cu 1.7 Clu/GAs, and Cu 1.4 Clu/GAs under soft X-ray were illustrated in Fig. 3 c. The a, b, and c regions represent different types of chemical bonds, which are π*C = C (286.1 eV), σ*C-O/C-Cu (~ 289.2 eV), and π*C-C (292.7 eV). Furthermore, the σ*C-O/C-Cu of Cu 1.7 Clu/GAs and Cu 1.4 Clu/GAs were enhanced after pulsed discharge, which is consistent with the above results of XPS and Raman. Figure 3 d exhibits the Cu K-edge X-ray absorption near edge structure (XANES) spectra of the Cu 1.7 Clu/GAs and the references (Cu foil, CuO, and Cu 2 O). The absorption edge of the Cu 1.7 Clu/GAs was between the CuO and Cu 2 O, demonstrating the oxidation state of Cu is in the middle valence state (+ 1 to + 2) 47, 48 . A marginally higher rising edge could be attributed to the electron transfer from the GAs support to the Cu 2 O nanocluster. The Fourier transformed (FT) k 3 -weighted extended X-ray absorption fine structure (EXAFS) spectra of Cu 1.7 Clu/GAs (Fig. 3 e) displayed an enhanced peak at 1.5 Å with a lower peak at 2.4 Å in R space. The enhanced peak came from the superimposed contribution of Cu-C and Cu-O, and the lower peak corresponding to the Cu-Cu bonds contribution revealed the existence of Cu 2 O clusters in Cu 1.7 Clu/GAs. The Cu K-edge wavelet transform (WT) EXAFS results of Cu 1.7 Clu/GAs and references are presented in Fig. 3 f. The high-intensity zone of the Cu 1.7 Clu/GAs in the first shell occupied a wider range than Cu foil, Cu 2 O, CuO, which originated from the joint contribution of Cu-C, Cu-O, and Cu-Cu. Figures 3 e, 3 g, and Supplementary Fig. 21 depict the fitting results of Cu 1.7 Clu/GAs in R space, q space, and k space, respectively. The fitting result confirmed that the Cu-O/C bond length is 1.92 Å with the coordination number (CN) 3.2, and the Cu-Cu bond length is 2.55 Å with the CN 1.0 (Supplementary Table 5), indicating that Cu atoms in Cu 1.7 Clu/GAs were predominately coordinated with C/O atoms. Moreover, the EXAFS spectrum and fitting results in R space of Cu 1.4 Clu/GAs, Cu 2.7 NPs/GAs, Cu 4.1 NPs/GAs, and Cu 7.5 NPs/GAs are shown in Supplementary Fig. 22, the Cu-Cu bond was gradually strengthened with the increase in size. The fitting results in k space and q space are shown in Supplementary Fig. 23, and the WT EXAFS results are displayed in Supplementary Fig. 24. Notably, The CN of Cu-C/O was increased and the CN of Cu-Cu was decreased because the oxidation degree of Cu was weakened when the nanoparticle size increased from 1.4 nm to 7.5 nm, which is consistent with the results of HADDF-STEM. Synthesis and structural characterization of M Clu/GAs (M = Fe, Co, Pt, Ru). The other metal clusters (M = Fe, Co, Pt, Ru) were easily generalized through the transient pulsed discharge synthesis strategy, only requiring the change of CuCl 2 to corresponding metal salts. Supplementary Figs. 25–28 present the HADDF-STEM images, XANES spectrum, FT-EXAFS, fitting, and WT EXAFS results of M Clu/GAs, they all exhibit uniform clusters on GAs with high quality. The best-fit structural parameters were shown in Supplementary Table 6, and the effect of strong metal/oxide with support existed on the M Clu/GAs. The extended investigations manifest the generality of the transient pulsed discharge strategy to construct unsymmetrical atomic structures and electronic structures for catalytic reactions. In situ tests of Cu 1.7 Clu/GAs. Investigating the atomic structure-activity relationship of Cu 1.7 Clu/GAs on the CO 2 RR process is essential to demonstrate the reaction mechanism. Therefore, i n situ XAFS is employed to reveal the practical catalytic centers of Cu 1.7 Clu/GAs on the electrochemical catalytic CO 2 RR (Supplementary Fig. 29). The in situ Cu K-edge XANES results of Cu 1.7 Clu/GAs at open circuit, -0.9 V, and − 1.1 V are displayed in Fig. 4 a. When the potential was changed, the sample underwent a drastic change. The energy at the absorption position gradually decreases as the potential decreases from 0 to -1.1 V (illustrated in Fig. 4 a), while the intensity of the white line peak decreases, indicating an alteration in the valence state of Cu in Cu 1.7 Clu/GAs. The FT-EXAFS spectra of Cu 1.7 Clu/GAs in the CO 2 RR process are presented in Fig. 4 b. The peak position of Cu-Cu slightly transferred to the left, which revealed that the bond lengths of Cu-Cu were compressed a bit with the applied potential decreased. On the contrary, the Cu-O/C coordination bonds were in a stretched state during the CO 2 RR process. In other words, the pinched Cu-Cu metal bonds provided mainly a large number of active sites for CO 2 RR. The fitting results are shown in Supplementary Fig. 30 and Supplementary Table 7, the Cu-Cu bonds were enhanced and the Cu-C/O bonds were weakened gradually with the decrease of the operated potentials. Figure 4 c displays the WT-EXAFS results of Cu 1.7 Clu/GAs at open circuit, -0.9 V, and − 1.1 V vs. RHE. The intensity maximum (~ 5.6 Å −1 ) at open circuit and − 0.9 V was similar to Cu 2 O or CuO. With the decrease of the operated potential, a new intensity maximum (~ 10 Å −1 ) was performed gradually, indicating that Cu 2 O clusters were reduced to ~ Cu 0 on the GAs. Moreover, the high-intensity zone at ~ 5 Å −1 was still maintained when the operated potential was − 1.1 V, indicating that there was still a strong interaction between Cu 0 clusters and graphene (GAs) at the interface. Furthermore, the normalized first derivative profiles of Cu K-edge XANES spectra with different potentials are shown in Supplementary Fig. 31. Furthermore, the oxidation state of Cu could be evaluated by comparing the peak position. The absorption edges were significantly changed with the decreased operated potential, which explicitly manifested that the process of CO 2 RR on Cu 1.7 Clu/GAs is potential-dependent. When the absorption edge of Cu shifts to the lower energy, it is usually considered a reduced Cu valence state. The specific valence state of Cu under different conditions is depicted in Fig. 4 d. The valence states of Cu in Cu 1.7 Clu/GAs were similar under ex-situ and open circuit conditions, and the valence state of Cu was between Cu + and Cu 2+ due to the strong oxide -support effect. Moreover, the bonding state of Cu was about 0.36 at -1.1 V, implying the active sites of CO 2 RR on Cu 1.7 Clu/GAs were jointly contributed by Cu-Cu and Cu-C/O. To further study the important adsorbed intermediates in the CO 2 RR process, the in situ ATR-FITR measurement was carried out at different operated potentials. Notably, distinct vibration peaks were detected at ~ 1450 cm − 1 when the operated potentials reached − 0.8 V vs. RHE (Fig. 4 e), which may originate from the vibration of antisymmetric *CH 3 . Moreover, two new bands at around 1770 cm − 1 and 1915 cm − 1 can be identified as the C = O groups and the produced CO bound to the Cu surface when the operating potential was below − 0.8 V vs. RHE. This implies that the H* radical is affected by other products at -0.8 V vs. RHE, which is consistent with the electrochemical test findings. Figure 4 f provides the evolution process of the Cu 1.7 Clu/GAs catalyst at different potential conditions. The Cu 2 O clusters were gradually reduced to Cu 0 nanoclusters with the decrease of operated potential, and the Cu 0 nanoclusters supported on r-GO exhibited excellent EtOH and C 2+ production capabilities in electrochemical catalytic CO 2 RR. After testing, Cu 0 nanoclusters were gradually oxidized into Cu 2 O clusters supported on r-GO due to their exposure to air. Theoretical investigation of Cu 4 -CuC 2 O 1 Clu/GAs on CO 2 RR. To get the insight of atomic-scale CO 2 reduction mechanism toward the C 2+ product (CH 3 CH 2 OH, C 2 H 4 , and CH 3 COOH) on the asymmetrical Cu 4 -CuC 2 O moiety, we carried out a detailed hydrogenation process study considering the possibility of different intermediates using density functional theory method. Fig. S32 shows the Cu 4 -CuC 2 O configuration in which Cu 4 cluster bonding on the CuC 2 O-graphene. CO 2 molecule can be easily captured on the Cu 4 clusters with the adsorption energy of -0.52 eV in Fig. S33. Figs. S34 and S35 display the optimized models of COOH and CO species. CO intermediate served as a key species to form C 2+ product through CO-CO dimerization, CO-CHO, or CO-COH coupling. Compared with the formed COH intermediate with 1.80 eV adsorption energy, Cu 4 -CuC 2 O was prone to generate the CHO species with lower adsorption energy with − 0.45 eV in Fig. S36. Figure 5 a shows the energy barrier of C-C coupling through the CO-CO and CO-CHO process, corresponding initial state (IS), transition state (TS), and final state (FS) in Figs. S37-S38. The CO-CHO coupling process had lower reaction energy and energy barrier with 0.30 eV and 1.28 eV than that of CO-CO dimerization with 1.81 eV and 2.13 eV. Based on the lower TS barrier, all the primary steps after C-C coupling were studied according to the CO-CHO species. The lowest energy pathways towards the identified CH 3 CH 2 OH, C 2 H 4 , and CH 3 COOH products were illustrated in Fig. 5 b, and the optimized models of intermediates were displayed in Figs. 5 c, S39, and S40. The CH 3 COOH path ramified at the sixth proton-coupled-electron transfer (PCET) step, while the CH 3 CH 2 OH and C 2 H 4 path shared the former eight PCETs, and furcated at the ninth coupled proton-electron-transfer process. The common intermediate for the CH 3 CH 2 OH and C 2 H 4 , such as *HCO-CHO (7b), was more superior to form than the intermediates of CH 3 COOH (7a), indicating the generation of CH 3 CH 2 OH and C 2 H 4 before CH 3 COOH 49, 50 . Free energy analysis further unearthed that the potential-determined step (PDS) of CH 3 CH 2 OH formation was 8b to 9c (*CHOHCHO→*CH 2 OHCHO) with the free energy change of 0.93 eV, much lower than that of C 2 H 4 with 1.41 eV, which also support the experimental findings. Conclusion In summary, we realized the precise adjustment on nano metal size during the formation of unsymmetrical Cu Clu/GAs catalysts by pulsed discharge strategy. A series of Cu Clu/GAs with different cluster sizes (1.4 nm, 1.7 nm, 2.7nm, 4.1nm, 7.5 nm) have been synthesized by adjusting the charging voltage from 7.4 kV to 9.0 kV. Among them, Cu 1.7 Clu/GAs for CO 2 RR including unsymmetrical Cu 4 -CuC 2 O 1 moieties distributed on GAs were conducted at a charging voltage of 8.6 kV by a transient pulsed discharge strategy. Benefitting from the precise adjustment of the unsymmetrical active moieties, the Cu 1.7 Clu/GAs catalysts performed optimal CO 2 RR activity and stability for EtOH and C 2+ production. The experimental studies and theoretical calculations demonstrated the enhanced electrochemical catalytic performance comes from the optimal unsymmetrical atomic structure and electronic structure feature of the concordantly Cu 4 -CuC 2 O 1 moieties. This work figures out the problem of balancing the activity and stability of asymmetric structured catalysts and constructs a novel structure-activity relationship in electrochemical catalysis. Methods Chemicals. Copper chloride (CuCl 2 , 99%, Alfa Aesar), Cobalt chloride (CoCl 2 , 99%, Alfa Aesar), Nickel chloride (NiCl 2 , 99%, Alfa Aesar), Hydrogen hexachloroplatinate (H 2 PtCl 4 •xH 2 O, 99.995%, Alfa Aesar), Ruthenium chloride (RuCl 2 , 99%, Alfa Aesar), methanol (analytical grade, Alfa Aesar), KHCO 3 (Sigma Aldrich), Nafion D-521 dispersion (5 wt%, Alfa Aesar). Preparation of Cu Clu/GAs . In a typical synthesis, the single-layer graphene oxide (GO) was diluted and mixed fully in deionized water (GO/H 2 O = 2 mg/g). The uniformly dispersed GO was put into a hydrothermal reactor, heated at 180 ℃ for 6 hours, and graphene hydrogel gradually formed. The graphene hydrogel was fully immersed in CuCl 2 aqueous solution for 5 hours, and then quickly frozen in liquid nitrogen. Subsequently, GA support CuCl 2 nanocrystals (CuCl 2 /GA) were formed by freeze-drying. Afterward, the as-prepared CuCl 2 /GA was filled into the copper discharge tube for the pulsed discharge process. Then the discharge tube containing CuCl 2 /GA was connected to the discharge circuit. The discharge voltage could be changed to produce different size metal clusters/nanoparticles supported by GAs. When the air switch is triggered, the intense pulsed current passes through the copper discharge tube and CuCl 2 /GA. The pulsed current and voltage features of Cu 1.7 Clu/GAs and other samples are displayed in Supplementary Note. 1. The CO 2 RR tests are presented in Supplementary Note. 2, the XAFS measurements and data processing are depicted in Supplementary Notes. 3-5. The in situ ATR-FTIR test and the details of DFT calculation methods are shown in Supplementary Notes. 6-7. 1 H Nuclear magnetic resonance analysis. The yield of liquid products, such as EtOH, n-PrOH during constant potential electrolysis (4,000 s) were quantified by nuclear magnetic resonance (NMR) spectroscopy 16 . These products were recorded on a Bruker Avance III NMR spectrometer operating at 11.7 T (500 MHz 1 H), and dimethyl sulfoxide (DMSO, 99.9%) was utilized as an internal standard. The same spectral acquisition parameters were used for all spectra to ensure full relaxation and quantification. The acquisition parameters were: time domain data size (65536); number of dummy scans (2); number of scans (16); spectral width (19.9899 ppm); loop count time domain (1); spectral width in Hertz (10,000Hz); filter width (125,000 Hz); pause width (45°); delay 1 (5 s) and delay 2 (0 s). For the NMR tests, a 700 µl electrolyte sample was mixed with 35 µl of internal standard solution (the mixture of 10.0 µl DMSO and 14 ml of D 2 O). Standard curves of each product were obtained by the ratio of relative peak area. Declarations Data availability The data supporting the findings of this study are available within the article and its Supplementary Information files. All other relevant source data are available from the corresponding authors upon reasonable request. Acknowledgements This work was supported by National Natural Science Foundation of China (Grant No. 12372332, 12002048 and 22375019), the Beijing Natural Science Foundation (Grant No. 2212018), Beijing Institute of Technology Research Fund Program for Young Scholars (Grant No. 2022CX01011 and Grant No. XSQD-202002004), and the Beijing Institute of Technology Research and Innovation Promoting Project (Grant No. 2022YCXZ003). The Start-up Foundation for Senior Talents of Jiangsu University (21JDG041), and the China Postdoctoral Science Foundation (2023M731357). We thank the theoretical calculations performed on A6 Zone of the Beijing Super Cloud Computing Center, supported by PARATERA. Author Contributions X.G. and P.C. conceived the idea, designed the research and wrote the paper. K.L. carried out the sample synthesis, characterization and wrote the paper. Z.S. performed CO 2 RR measurement. W.C. carried out the i n situ synchrotron radiation XAFS measurements and data analysis. Q.Z. revised this paper. H.S., G.L. and Z.S. performed the DFT calculations and processed the data. All the authors discussed the results and commented on the manuscript. Competing interests The authors declare no competing interests. Additional information Supplementary information is available for this paper. Correspondence and requests for materials should be addressed to Z. S., W.C., X.G., or P.C. References Lees EW et al (2022) Gas diffusion electrodes and membranes for CO 2 reduction electrolysers. Nat Rev Mater 7:55–64 Zheng Y et al (2019) Understanding the roadmap for electrochemical reduction of CO 2 to multi-carbon oxygenates and hydrocarbons on copper-based catalysts. J Am Chem Soc 141:7646–7659 Birdja YY et al (2019) Advances and challenges in understanding the electrocatalytic conversion of carbon dioxide to fuels. 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Nano Res. https://doi.org/10.1007/s12274-023-6301-y Du C, Mills JP, Yohannes AG et al (2023) Cascade electrocatalysis via AgCu single-atom alloy and Ag nanoparticles in CO 2 electroreduction toward multicarbon products. Nat Commun 14:6142 Additional Declarations There is NO Competing Interest. Supplementary Files SI.docx Cite Share Download PDF Status: Published Journal Publication published 31 Jan, 2025 Read the published version in Nature Communications → 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. 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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-3991307","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":279811849,"identity":"6bc64303-361c-4084-a6e9-08163e9bfc6b","order_by":0,"name":"Wenxing 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1","display":"","copyAsset":false,"role":"figure","size":895514,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe synthesis and characterizations of Cu\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1.7\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e Clu/GAs. a \u003c/strong\u003eA schematic plot of the preparation strategy by the transient pulsed discharge.\u003cstrong\u003e b\u003c/strong\u003e The current curve of the circuit in the Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs synthesis process. \u003cstrong\u003ec\u003c/strong\u003e Photomacrograph of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs. \u003cstrong\u003ed\u003c/strong\u003e EDS mapping images, C (red), O (green), and Cu (yellow). \u003cstrong\u003ee\u003c/strong\u003e a HAADF-STEM figure (dark field). \u003cstrong\u003ef\u003c/strong\u003e The local magnified image of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs. \u003cstrong\u003eg\u003c/strong\u003e Nanoclusters size distribution frequency.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3991307/v1/2d172145b9f48351c8d1c286.png"},{"id":52870419,"identity":"78e6204e-1da3-44fb-ba5a-68a3cf1e51fe","added_by":"auto","created_at":"2024-03-18 07:04:51","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":202907,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCO\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eRR performance of Cu\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1.7\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e Clu/GAs.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e LSV curves of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, Cu SAs/GAs, and Cu NPs/GAs measured in CO\u003csub\u003e2\u003c/sub\u003e saturated electrolyte. \u003cstrong\u003eb\u003c/strong\u003e The FE of EtOH production detected by gas chromatography. \u003cstrong\u003ec\u003c/strong\u003e The local current density of EtOH. \u003cstrong\u003ed\u003c/strong\u003e The FEs of all products on Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at different potentials. \u003cstrong\u003ee\u003c/strong\u003e The long-term stability measurement of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at -1.1 V vs. RHE.\u003cstrong\u003e f\u003c/strong\u003e The comprehensive performance of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs. \u003cstrong\u003eg\u003c/strong\u003e The schematic draw of the flow cell. \u003cstrong\u003eh\u003c/strong\u003e LSV curve of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs in the flow cell.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3991307/v1/10ef981ae88554b58538929e.png"},{"id":52870418,"identity":"ba14c607-c470-4ebc-98f2-22f0ee28fd69","added_by":"auto","created_at":"2024-03-18 07:04:51","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":281298,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAtomic coordination structure and chemical state of Cu\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1.7\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e Clu/GAs.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e Cu 2p XPS spectra of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and Cu NPs/GAs.\u003cstrong\u003e b\u003c/strong\u003e The C 1s XPS spectra of Cu NPs/GAs, Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and GAs. \u003cstrong\u003ec\u003c/strong\u003e XRD of Cu NPs/GAs, Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and GAs. \u003cstrong\u003ed\u003c/strong\u003e The Cu K-edge XANES spectra of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and the references (Cu foil, Cu, CuO). \u003cstrong\u003ee\u003c/strong\u003e Cu K-edge FT \u003cem\u003ek\u003c/em\u003e\u003csup\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sup\u003e-weighted EXAFS spectra of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and references. \u003cstrong\u003ef\u003c/strong\u003e The WT-EXAFS profiles of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, Cu foil, Cu\u003csub\u003e2\u003c/sub\u003eO, and CuO. \u003cstrong\u003eg\u003c/strong\u003e The EXAFS fitting result of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs in the R space. \u003cstrong\u003eh\u003c/strong\u003e EXAFS fitting curve of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs in q space.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3991307/v1/9a547af1c69c637457bbc2c1.png"},{"id":52870423,"identity":"d9127dfa-7bce-4c66-9878-95b813cb0515","added_by":"auto","created_at":"2024-03-18 07:04:51","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":402500,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eIn situ\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e XAFS characterizations of Cu\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1.7\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e Clu/GAs. a \u003c/strong\u003eThe\u003cstrong\u003e \u003c/strong\u003eCu K-edge XANES spectra of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at different potentials during the CO\u003csub\u003e2\u003c/sub\u003eRR process. \u003cstrong\u003eb \u003c/strong\u003eThe\u003cstrong\u003e \u003c/strong\u003eFT-EXAFS curves of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at ex-situ, open circuit, -0.9 V, and -1.1 V \u003cem\u003evs.\u003c/em\u003e RHE. \u003cstrong\u003ec\u003c/strong\u003e WT-EXAFS profiles of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at different potentials. \u003cstrong\u003ed\u003c/strong\u003e The calculated bonding state of Cu in Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at different potentials and references. \u003cstrong\u003ee\u003c/strong\u003e \u003cem\u003eIn situ\u003c/em\u003e ATR-FTIR results of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at different potentials. \u003cstrong\u003ef\u003c/strong\u003e Proposed strategy for the process of electrocatalytic CO\u003csub\u003e2\u003c/sub\u003eRR to produce ethanol on Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at different potentials (yellow, O; blue, C; red, Cu).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3991307/v1/ae4e5c36f0be110b37f641a3.png"},{"id":52870420,"identity":"769f5bef-ae44-41e1-b6e1-cf30608ee71c","added_by":"auto","created_at":"2024-03-18 07:04:51","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":207234,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTheoretical CO\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eRR activity of Cu\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1.7\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e Clu/GAs.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e The energy barrier of C-C coupling through CO-CO and CO-CHO dimerization, inset is the transition state. \u003cstrong\u003eb\u003c/strong\u003e Electrochemical CO\u003csub\u003e2\u003c/sub\u003e reduction pathway to CH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003eOH, C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e, CH\u003csub\u003e3\u003c/sub\u003eCOOH. \u003cstrong\u003ec\u003c/strong\u003e The optimized configurations of CH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003eOH intermediates. Orange, red, white, and gray ball marks Cu, O, H, and C atoms, respectively.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-3991307/v1/88d7c97015fb92e2c35a7843.png"},{"id":75148606,"identity":"63368e0d-4521-465d-991a-0d35ebbd7690","added_by":"auto","created_at":"2025-01-31 08:07:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2880622,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3991307/v1/049e849a-24a0-43b5-a7e9-461a4b003e11.pdf"},{"id":52870424,"identity":"af3c92fc-3661-4845-9af3-9b13911c3b29","added_by":"auto","created_at":"2024-03-18 07:04:53","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":134575757,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"SI.docx","url":"https://assets-eu.researchsquare.com/files/rs-3991307/v1/be1641f9647b56eedae9cd64.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Transient Pulsed Discharge Preparation of Graphene Aerogel Supported Asymmetric Cu Cluster Catalysts Promote CO2 Reduction to Ethanol","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe electrochemical catalytic carbon dioxide reduction reaction (CO\u003csub\u003e2\u003c/sub\u003eRR) driven by renewable electricity provides a green solution for energy and environmental crises\u003csup\u003e1, 2\u003c/sup\u003e. Multi-carbon compounds (C\u003csub\u003e2+\u003c/sub\u003e), such as ethylene, ethanol, and propanol, have higher accessional value compared to single-carbon organic products (C\u003csub\u003e1\u003c/sub\u003e)\u003csup\u003e3, 4\u003c/sup\u003e. Among them, ethanol (EtOH) is considered an outstanding liquid fuel and industrial chemical owing to its significant energy density and wide range of applications\u003csup\u003e5\u0026ndash;7\u003c/sup\u003e. Besides, EtOH also possesses the advantages of long-term storage, ease of transportation, and scalability\u003csup\u003e8, 9\u003c/sup\u003e. Recently, multiple investigations have demonstrated that copper-based catalysts feature a highly efficient conversion from carbon dioxide to C\u003csub\u003e2+\u003c/sub\u003e products, with high selectivity. However, their selectivity and current density for producing EtOH are still under improvement\u003csup\u003e10\u0026ndash;12\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eNano metals or metal oxides supported-type catalysts feature plenty of nano heterostructures consisting of metal atoms and adjacent coordination species on the support, whose precisely adjustable structure advantages the design of efficient nanocatalysts\u003csup\u003e13\u0026ndash;15\u003c/sup\u003e. The carbon-supported nano Cu or CuO\u003csub\u003ex\u003c/sub\u003e catalysts rely on the absorption features of the *CO and *H on the Cu atoms, these catalysts could enhance their selectivity of C\u003csub\u003e2+\u003c/sub\u003e products and EtOH\u003csup\u003e16, 17\u003c/sup\u003e. Furthermore, related researches have revealed that their low coordination Cu atoms in Cu nanoparticles are the source of CO\u003csub\u003e2\u003c/sub\u003eRR catalytic active sites\u003csup\u003e18, 19\u003c/sup\u003e. The decreasing size of metal nanoparticles increases the specific surface of the metal with more active atoms, enhancing the catalytic activity\u003csup\u003e20\u0026ndash;22\u003c/sup\u003e. Consequently, the metal clusters (\u0026lt;\u0026thinsp;2 nm) feature outstanding catalytic performance compared to the corresponding metal nanoparticles\u003csup\u003e23\u0026ndash;25\u003c/sup\u003e. Additionally, optimizing the local structure and coordination of carbon-supported copper cluster catalysts can further enhance the catalytic activity of copper clusters by regulating the interaction between active sites and supports\u003csup\u003e26, 27\u003c/sup\u003e. The adjustment of cluster dispersion on the support is one efficient route to optimize the local structure which could change the electronic state of active sites, and affect the reaction pathway with different catalytic mechanism\u003csup\u003e28, 29\u003c/sup\u003e. However, the multi-step synthetic pathway from CO\u003csub\u003e2\u003c/sub\u003eRR to ethanol could lead to the high energy barrier and complex mechanism of the C-C coupling process. Thus, it is still a significant challenge for designing catalysts with clear active sites\u003csup\u003e30\u0026ndash;32\u003c/sup\u003e to investigate the action of active sites in the EtOH production process of CO\u003csub\u003e2\u003c/sub\u003eRR and the structure-activity relationship in electrochemical catalytic reactions. The delicate design of Cu nanoclusters on carbon matrix can significantly enhance the catalytic efficiency\u003csup\u003e33\u0026ndash;35\u003c/sup\u003e. Meanwhile, the customization of accurate metal-support coordination structures contributes to the study of structure-activity relationships\u003csup\u003e36\u003c/sup\u003e. Researchers have utilized various strategies to synthesize designed metal cluster/carbon matrix specimens\u003csup\u003e37\u0026ndash;41\u003c/sup\u003e for further investigation on the electrochemical catalytic reactions.\u003c/p\u003e \u003cp\u003eHerein, novel graphene aerogels support Cu nanocluster catalysts (Cu Clu/GAs) with Cu\u003csub\u003e4\u003c/sub\u003e-CuC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e1\u003c/sub\u003e atomic interaction structures and outstanding properties are prepared by a pulsed discharge strategy efficiently. The size of nano coppers on GA can be modulated from 1.4 nm to 7.5 nm by pulsed discharge conditions. Impressively, the Cu Clu/GAs exhibit excellent selectivity and activity in CO\u003csub\u003e2\u003c/sub\u003eRR to produce EtOH. Moreover, they propose a long-term stability (\u0026gt;\u0026thinsp;60 h). The Cu Clu/GAs with asymmetric distribution of atomic and electronic coordination structures are confirmed through atomic-level structural analysis. \u003cem\u003eIn situ\u003c/em\u003e X-ray absorption fine structure (XAFS) measurements for Cu Clu/GA demonstrate that the asymmetric Cu\u003csub\u003e4\u003c/sub\u003e-CuC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e1\u003c/sub\u003e moieties could promote the EtOH production in the electrocatalytic CO\u003csub\u003e2\u003c/sub\u003eRR process. The main intermediates are detected by \u003cem\u003ein situ\u003c/em\u003e attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FITR) test. The pathways of CO\u003csub\u003e2\u003c/sub\u003eRR on Cu\u003csub\u003e4\u003c/sub\u003e-CuC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e1\u003c/sub\u003e are figured out by the calculation of density functional theory (DFT). Additionally, other metal clusters supported by GAs (M Clu/GAs, M\u0026thinsp;=\u0026thinsp;Fe, Co, Pt, Ru) with asymmetric structures could be synthesized by similar pulsed discharge processes.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cp\u003e \u003cb\u003eSynthesis and morphology characterizations of Cu Clu/GAs.\u003c/b\u003e Graphene hydrogel (GH) could be prepared by the hydrothermal assembly method\u003csup\u003e41\u003c/sup\u003e. The graphene oxide solvent was poured into a glass bottle with an inner diameter of 15 mm and a depth of 25 mm. The copper chloride was added to the suspension to form a certain concentration of CuCl\u003csub\u003e2\u003c/sub\u003e solvent. The GH was immersed in the CuCl\u003csub\u003e2\u003c/sub\u003e solvent for 5 hours. Then the beaker including GH and solvent were frozen using liquid nitrogen. During the frozen vacuum drying process, the ice sublimated and the CuCl\u003csub\u003e2\u003c/sub\u003e nano-crystals were separated on the surface of graphene aerogel (GA, Supplementary Fig.\u0026nbsp;1). Then the GA in size of Φ9\u0026times;15 mm was fabricated (with CuCl\u003csub\u003e2\u003c/sub\u003e 5 wt%). The content of CuCl\u003csub\u003e2\u003c/sub\u003e can be modified by the mass of CuCl\u003csub\u003e2\u003c/sub\u003e in the bottle. The CuCl\u003csub\u003e2\u003c/sub\u003e/GAs were compressed into the copper tube by copper plugs. Subsequently, the tube was fixed with two electrodes for discharge (Supplementary Figs.\u0026nbsp;2 and 3). After the charging of the capacitor, the air switch was triggered for pulsed discharge. The CuCl\u003csub\u003e2\u003c/sub\u003e would be decomposed into Cu and chlorine (Cl\u003csub\u003e2\u003c/sub\u003e) rapidly in the discharge tube due to the transient Joule heating. After pulsed discharge, the decomposed Cu atoms converged to form Cu clusters on the GAs during a rapid cooling process to form Cu Clu/GA specimens. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea presents the formation schematic diagram of Cu Clu/GA.\u003c/p\u003e \u003cp\u003eA presentative discharge current waveform in the copper discharge tube containing a CuCl\u003csub\u003e2\u003c/sub\u003e/GA is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb and Supplementary Fig.\u0026nbsp;4, revealing the typical current-voltage (I-U) waveforms in the resistance-inductance-capacitance (RLC) circuit during the pulsed discharge. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec is the photo of Cu Clu/GA on a flower, presenting its extremely low density. Carbon-based supports loaded metal nanocluster catalysts could be rapidly synthesized under the transient pulsed discharge technology (Supplementary Fig.\u0026nbsp;5). Especially, the I-U curves indicate that the resistance of the circuit did not change during the pulsed discharge process, implying that the GA support was no decomposition and phase change after the transient pulsed discharge treatment, as evidenced in the recovered intact GA after pulsed discharge. Moreover, the intense current pulse can generate an intense electromagnetic field and induce multiple transient high temperature zones on GA. Meanwhile, the CuCl\u003csub\u003e2\u003c/sub\u003e nano-crystals in GA decomposed to form Cu\u003csup\u003e2+\u003c/sup\u003e and *Cl ions under the action of high temperature. These ions burst out and agglomerate to form clusters anchoring on the GA support during pulsed discharge, due to the action of the intense pulsed electromagnetic field in the copper tube. In addition, the air in the porous GA may form multiple local corona discharge plasma, consisting of O ions and N ions, and may form strong atomic interactions between metal clusters and GA support. Moreover, during the pulsed discharge process, the magnetic pinch effect caused by the dynamic electromagnetic field inhibits the radial expansion of the formed ions\u003csup\u003e42\u003c/sup\u003e, which maintain a relatively high-density plasma including Cu, and O ions in GA. Consequently, the mixed Cu and O ions agglomerate to form clusters on the defects of graphene. Cu clusters/nanoparticles of various sizes (1.4 nm, 1.7 nm, 2.7 nm, 4.1 nm, and 7.5 nm) were rapidly synthesized and securely anchored onto graphene by adjusting the charging voltage to increase the pulsed discharge duration. They are identified as Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs, Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, Cu\u003csub\u003e2.7\u003c/sub\u003e NPs/GAs, Cu\u003csub\u003e4.1\u003c/sub\u003e NPs/GAs, and Cu\u003csub\u003e7.5\u003c/sub\u003e NPs/GAs, respectively (Supplementary Figs.\u0026nbsp;6\u0026ndash;10). The results in Supplementary Table\u0026nbsp;1 indicate that inputting higher energy in a shorter time would result in the formation of smaller Cu nanoparticles on GAs.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe 3D porous structure of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GA is also performed by scanning electron microscope (SEM), and many clusters are distributed on graphene by the transmission electron microscopy (TEM) (Supplementary Fig.\u0026nbsp;7). Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed shows the mapping energy dispersive spectrum of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, where the carbon (C), oxygen (O), Cu elements are uniformly distributed in the reduced graphene oxide (r-GO). The energy dispersive spectrometer (EDS) mapping results displayed the Cu atoms content of approximately 1.83 at%. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee presents a high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, plenty of clusters were dispersed onto the graphene. Uniformly sized Cu clusters were so evenly seeded on graphene because the instantaneous characteristics of pulsed discharge inhibit the continued growth of these Cu clusters. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef shows the higher magnification HAADF-STEM image of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, and some local crystal plane spacing could be measured, while the Cu\u003csub\u003e2\u003c/sub\u003eO crystal features were identified. Nanoclusters exhibit severe lattice distortion, which is due to the thermal effect and electromigration coupling effect generated by high-frequency pulsed discharge, resulting in atomic diffusion at different speeds in different directions. Meanwhile, Cu nanoclusters are highly susceptible to oxidation due to their high specific surface energy. Subsequently, the diameters of these nanoclusters were counted by the Nanomeasure software, and the distribution of frequency-diameter was shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg. It can be seen that the diameters range is from 1.2 nm to 2.6 nm, and the proportion of nanoclusters with a diameter of 1.5 nm is the highest (~\u0026thinsp;30%), and the average diameter is 1.7 nm.\u003c/p\u003e \u003cp\u003e \u003cb\u003eElectrocatalytic characterizations.\u003c/b\u003e The electrocatalytic CO\u003csub\u003e2\u003c/sub\u003eRR performance of Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs, Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, Cu\u003csub\u003e2.7\u003c/sub\u003e NP/GAs, Cu\u003csub\u003e4.1\u003c/sub\u003e NP/GAs, and Cu\u003csub\u003e7.5\u003c/sub\u003e NP/GAs was evaluated by an H-type cell (Supplementary Fig.\u0026nbsp;11). Linear sweep voltammetry (LSV) plots (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea) are employed to acquire polarisation curves in the CO\u003csub\u003e2\u003c/sub\u003e-saturated 0.5 M KHCO\u003csub\u003e3\u003c/sub\u003e aqueous solution. Moreover, the activity of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs exhibited the lowest onset potential and the fastest decreasing current density in all samples. The FEs of EtOH (FEs\u003csub\u003eEtOH\u003c/sub\u003e) were obtained at different potentials (from \u0026minus;\u0026thinsp;0.8 V to -1.2 V) for Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and Cu\u003csub\u003e7.5\u003c/sub\u003e NP/GAs, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb. Impressively, the FE\u003csub\u003eEtOH\u003c/sub\u003e of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs reached 75.3% at -1.1 V, while the FEs\u003csub\u003eEtOH\u003c/sub\u003e of other samples (Supplementary Fig.\u0026nbsp;12) remained at the relatively lower level in the wide potential range. Furthermore, the FEs\u003csub\u003eEtOH\u003c/sub\u003e of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs could be maintained\u0026thinsp;\u0026gt;\u0026thinsp;55% at -0.9 V to -1.2 V, exhibiting outstanding selectivity on EtOH production from CO\u003csub\u003e2\u003c/sub\u003eRR, which was better than the performances of Cu\u003csub\u003e2.7\u003c/sub\u003e NPs/GAs, Cu\u003csub\u003e4.1\u003c/sub\u003e NPs/GAs, and Cu\u003csub\u003e7.5\u003c/sub\u003e NPs/GAs. Moreover, the local current densities of EtOH (J\u003csub\u003eEtOH\u003c/sub\u003e) of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs were calculated (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec) from \u0026minus;\u0026thinsp;0.8 V to -1.2 V, and the optimal J\u003csub\u003eEtOH\u003c/sub\u003e was \u0026minus;\u0026thinsp;33.5 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e at -1.1 V. The current densities of other samples were weaker than that of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at the potential range. Impressively, the performance of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs exceeded the most listed electrochemical catalysts on CO\u003csub\u003e2\u003c/sub\u003eRR-to-EtOH in recent literature (Supplementary Fig.\u0026nbsp;13 and Supplementary Table\u0026nbsp;2). Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed provides the FEs of various products on Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at the operated potential from \u0026minus;\u0026thinsp;0.6 V to -1.2 V vs. RHE. The main products were H\u003csub\u003e2\u003c/sub\u003e and CO at the higher potentials (-0.6 V and \u0026minus;\u0026thinsp;0.7 V), and the product of EtOH was first detected when the potential decreased to -0.8 V (Supplementary Table\u0026nbsp;3), EtOH dominated at lower potentials (from \u0026minus;\u0026thinsp;0.9 V to -1.2 V). Meanwhile, the FEs of C\u003csub\u003e1\u003c/sub\u003e, and C\u003csub\u003e2+\u003c/sub\u003e, H\u003csub\u003e2\u003c/sub\u003e, were counted and presented in Supplementary Fig.\u0026nbsp;14, and FE\u003csub\u003eC2+\u003c/sub\u003e reached a surprising 90.5%. Additionally, the CO\u003csub\u003e2\u003c/sub\u003eRR performance of Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs at different potentials was provided in Supplementary Fig.\u0026nbsp;12 and Supplementary Table\u0026nbsp;4, the FE\u003csub\u003eEtOH\u003c/sub\u003e reached a decent 66.5% at -0.9 V.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe long-term stability of CO\u003csub\u003e2\u003c/sub\u003eRR is crucial and the potential issue of metal dissolution should not be overlooked. The stability measurement results of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee, the FE\u003csub\u003eEtOH\u003c/sub\u003e of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs keep on \u0026gt;\u0026thinsp;74% with a negligible current density loss at the operated potential of -1.1 V during the 60 h stability measurement. At the same time, all the J\u003csub\u003eEtOH\u003c/sub\u003e remain below \u0026minus;\u0026thinsp;33.0 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e from beginning to end. These indicate that Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs possess excellent stability in the electrocatalytic CO\u003csub\u003e2\u003c/sub\u003eRR process. The comprehensive performance of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs is evaluated in the electrochemical catalytic CO\u003csub\u003e2\u003c/sub\u003eRR process, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef. Compared to Cu/N\u003csub\u003e0.14\u003c/sub\u003eC\u003csup\u003e36\u003c/sup\u003e and Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs, the Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs is the most versatile. The CO\u003csub\u003e2\u003c/sub\u003eRR performance of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs in a flow cell (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eg) was conducted, and the result is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eh and Supplementary Fig.\u0026nbsp;15. The FE\u003csub\u003eEtOH\u003c/sub\u003e and J\u003csub\u003eEtOH\u003c/sub\u003e reached 68.7% and \u0026minus;\u0026thinsp;343.8 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e at -1.1 V vs. RHE respectively, which were competitive compared to previous report (Supplementary Table\u0026nbsp;2). Furthermore, the stability measurement manifested that the loss of applied potential and FE\u003csub\u003eEtOH\u003c/sub\u003e were ignorable at -343.8 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e for Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs. The impressive activity, selectivity, and stability of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs make it a promising candidate for practical electrode applications in electrocatalytic CO\u003csub\u003e2\u003c/sub\u003eRR for EtOH production.\u003c/p\u003e \u003cp\u003e \u003cb\u003eAtomic coordination structure and chemical state analysis of Cu\u003c/b\u003e \u003csub\u003e \u003cb\u003e1.7\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eClu/GAs.\u003c/b\u003e Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea illustrates the high-resolution Cu 2p XPS spectra of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs. Two main peaks at 953.4 eV (Cu 2p\u003csub\u003e1/2\u003c/sub\u003e) and 933.6 eV (Cu 2p\u003csub\u003e3/2\u003c/sub\u003e) were usually allocated to either Cu\u003csup\u003e0\u003c/sup\u003e or Cu\u003csup\u003e+\u0026thinsp;43\u003c/sup\u003e in Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs. C 1s XPS spectrum of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs present an additional peak at 282.9 eV corresponding to the Cu-C bond (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb and Supplementary Fig.\u0026nbsp;16c), which implies the effect of strong oxide-support interaction existed possibly between Cu\u003csub\u003e2\u003c/sub\u003eO/CuO clusters and GAs\u003csup\u003e44, 45\u003c/sup\u003e. The oxygen content is highest in Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs, second in Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, and lowest in GAs (Supplementary Figs.\u0026nbsp;16\u0026ndash;18), indicating that additional oxygen is introduced from the atmosphere during the process of pulsed discharge synthesis of Cu Clu/GAs. X-ray diffraction (XRD) reveals a broad peak from the (002) of the GAs (Supplementary Fig.\u0026nbsp;19), the weak peaks of Cu were displayed in Cu\u003csub\u003e7.5\u003c/sub\u003e NPs/GAs. However, no diffraction peaks corresponding to Cu\u003csub\u003e2\u003c/sub\u003eO crystals were detected in Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, which indicates that the size of the Cu\u003csub\u003e2\u003c/sub\u003eO clusters may be below the detection limit\u003csup\u003e46\u003c/sup\u003e. Raman spectroscopy was further employed to study the defect on GAs, two significant peaks at 1343 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1585 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represent the characteristics of graphene (Supplementary Fig.\u0026nbsp;20). The value of I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e increased to 1.19 from 1.09, indicating an increase in defects in graphene after the transient pulsed discharge. Combined with the analysis of XPS results, the formation of C-Cu bonds and the entry of oxygen atoms in the Cu Clu/GAs may be the main reasons for the increase of I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e. X-ray absorption spectroscopy (XAS) was utilized to further study the geometric and electronic structure of Cu Clu/GAs. The C K-edge absorption spectrum of GAs, Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs, and Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs under soft X-ray were illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec. The a, b, and c regions represent different types of chemical bonds, which are π*C\u0026thinsp;=\u0026thinsp;C (286.1 eV), σ*C-O/C-Cu (~\u0026thinsp;289.2 eV), and π*C-C (292.7 eV). Furthermore, the σ*C-O/C-Cu of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs were enhanced after pulsed discharge, which is consistent with the above results of XPS and Raman.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed exhibits the Cu K-edge X-ray absorption near edge structure (XANES) spectra of the Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and the references (Cu foil, CuO, and Cu\u003csub\u003e2\u003c/sub\u003eO). The absorption edge of the Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs was between the CuO and Cu\u003csub\u003e2\u003c/sub\u003eO, demonstrating the oxidation state of Cu is in the middle valence state (+\u0026thinsp;1 to +\u0026thinsp;2)\u003csup\u003e47, 48\u003c/sup\u003e. A marginally higher rising edge could be attributed to the electron transfer from the GAs support to the Cu\u003csub\u003e2\u003c/sub\u003eO nanocluster. The Fourier transformed (FT) k\u003csup\u003e3\u003c/sup\u003e-weighted extended X-ray absorption fine structure (EXAFS) spectra of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee) displayed an enhanced peak at 1.5 \u0026Aring; with a lower peak at 2.4 \u0026Aring; in R space. The enhanced peak came from the superimposed contribution of Cu-C and Cu-O, and the lower peak corresponding to the Cu-Cu bonds contribution revealed the existence of Cu\u003csub\u003e2\u003c/sub\u003eO clusters in Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs. The Cu K-edge wavelet transform (WT) EXAFS results of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and references are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef. The high-intensity zone of the Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs in the first shell occupied a wider range than Cu foil, Cu\u003csub\u003e2\u003c/sub\u003eO, CuO, which originated from the joint contribution of Cu-C, Cu-O, and Cu-Cu. Figures\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg, and Supplementary Fig.\u0026nbsp;21 depict the fitting results of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs in R space, q space, and k space, respectively. The fitting result confirmed that the Cu-O/C bond length is 1.92 \u0026Aring; with the coordination number (CN) 3.2, and the Cu-Cu bond length is 2.55 \u0026Aring; with the CN 1.0 (Supplementary Table\u0026nbsp;5), indicating that Cu atoms in Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs were predominately coordinated with C/O atoms. Moreover, the EXAFS spectrum and fitting results in R space of Cu\u003csub\u003e1.4\u003c/sub\u003e Clu/GAs, Cu\u003csub\u003e2.7\u003c/sub\u003e NPs/GAs, Cu\u003csub\u003e4.1\u003c/sub\u003e NPs/GAs, and Cu\u003csub\u003e7.5\u003c/sub\u003e NPs/GAs are shown in Supplementary Fig.\u0026nbsp;22, the Cu-Cu bond was gradually strengthened with the increase in size. The fitting results in k space and q space are shown in Supplementary Fig.\u0026nbsp;23, and the WT EXAFS results are displayed in Supplementary Fig.\u0026nbsp;24. Notably, The CN of Cu-C/O was increased and the CN of Cu-Cu was decreased because the oxidation degree of Cu was weakened when the nanoparticle size increased from 1.4 nm to 7.5 nm, which is consistent with the results of HADDF-STEM.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis and structural characterization of M Clu/GAs (M\u0026thinsp;=\u0026thinsp;Fe, Co, Pt, Ru).\u003c/b\u003e The other metal clusters (M\u0026thinsp;=\u0026thinsp;Fe, Co, Pt, Ru) were easily generalized through the transient pulsed discharge synthesis strategy, only requiring the change of CuCl\u003csub\u003e2\u003c/sub\u003e to corresponding metal salts. Supplementary Figs.\u0026nbsp;25\u0026ndash;28 present the HADDF-STEM images, XANES spectrum, FT-EXAFS, fitting, and WT EXAFS results of M Clu/GAs, they all exhibit uniform clusters on GAs with high quality. The best-fit structural parameters were shown in Supplementary Table\u0026nbsp;6, and the effect of strong metal/oxide with support existed on the M Clu/GAs. The extended investigations manifest the generality of the transient pulsed discharge strategy to construct unsymmetrical atomic structures and electronic structures for catalytic reactions.\u003c/p\u003e \u003cp\u003e \u003cb\u003eIn situ\u003c/b\u003e \u003cb\u003etests of Cu\u003c/b\u003e\u003csub\u003e\u003cb\u003e1.7\u003c/b\u003e\u003c/sub\u003e \u003cb\u003eClu/GAs.\u003c/b\u003e Investigating the atomic structure-activity relationship of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs on the CO\u003csub\u003e2\u003c/sub\u003eRR process is essential to demonstrate the reaction mechanism. Therefore, i\u003cem\u003en situ\u003c/em\u003e XAFS is employed to reveal the practical catalytic centers of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs on the electrochemical catalytic CO\u003csub\u003e2\u003c/sub\u003eRR (Supplementary Fig.\u0026nbsp;29). The \u003cem\u003ein situ\u003c/em\u003e Cu K-edge XANES results of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at open circuit, -0.9 V, and \u0026minus;\u0026thinsp;1.1 V are displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea. When the potential was changed, the sample underwent a drastic change. The energy at the absorption position gradually decreases as the potential decreases from 0 to -1.1 V (illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea), while the intensity of the white line peak decreases, indicating an alteration in the valence state of Cu in Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs. The FT-EXAFS spectra of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs in the CO\u003csub\u003e2\u003c/sub\u003eRR process are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb. The peak position of Cu-Cu slightly transferred to the left, which revealed that the bond lengths of Cu-Cu were compressed a bit with the applied potential decreased. On the contrary, the Cu-O/C coordination bonds were in a stretched state during the CO\u003csub\u003e2\u003c/sub\u003eRR process. In other words, the pinched Cu-Cu metal bonds provided mainly a large number of active sites for CO\u003csub\u003e2\u003c/sub\u003eRR. The fitting results are shown in Supplementary Fig.\u0026nbsp;30 and Supplementary Table\u0026nbsp;7, the Cu-Cu bonds were enhanced and the Cu-C/O bonds were weakened gradually with the decrease of the operated potentials. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec displays the WT-EXAFS results of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs at open circuit, -0.9 V, and \u0026minus;\u0026thinsp;1.1 V vs. RHE. The intensity maximum (~\u0026thinsp;5.6 \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e) at open circuit and \u0026minus;\u0026thinsp;0.9 V was similar to Cu\u003csub\u003e2\u003c/sub\u003eO or CuO. With the decrease of the operated potential, a new intensity maximum (~\u0026thinsp;10 \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e) was performed gradually, indicating that Cu\u003csub\u003e2\u003c/sub\u003eO clusters were reduced to ~\u0026thinsp;Cu\u003csup\u003e0\u003c/sup\u003e on the GAs. Moreover, the high-intensity zone at ~\u0026thinsp;5 \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e was still maintained when the operated potential was \u0026minus;\u0026thinsp;1.1 V, indicating that there was still a strong interaction between Cu\u003csup\u003e0\u003c/sup\u003e clusters and graphene (GAs) at the interface.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFurthermore, the normalized first derivative profiles of Cu K-edge XANES spectra with different potentials are shown in Supplementary Fig.\u0026nbsp;31. Furthermore, the oxidation state of Cu could be evaluated by comparing the peak position. The absorption edges were significantly changed with the decreased operated potential, which explicitly manifested that the process of CO\u003csub\u003e2\u003c/sub\u003eRR on Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs is potential-dependent. When the absorption edge of Cu shifts to the lower energy, it is usually considered a reduced Cu valence state. The specific valence state of Cu under different conditions is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed. The valence states of Cu in Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs were similar under ex-situ and open circuit conditions, and the valence state of Cu was between Cu\u003csup\u003e+\u003c/sup\u003e and Cu\u003csup\u003e2+\u003c/sup\u003e due to the strong oxide -support effect. Moreover, the bonding state of Cu was about 0.36 at -1.1 V, implying the active sites of CO\u003csub\u003e2\u003c/sub\u003eRR on Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs were jointly contributed by Cu-Cu and Cu-C/O.\u003c/p\u003e \u003cp\u003eTo further study the important adsorbed intermediates in the CO\u003csub\u003e2\u003c/sub\u003eRR process, the \u003cem\u003ein situ\u003c/em\u003e ATR-FITR measurement was carried out at different operated potentials. Notably, distinct vibration peaks were detected at ~\u0026thinsp;1450 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e when the operated potentials reached \u0026minus;\u0026thinsp;0.8 V vs. RHE (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee), which may originate from the vibration of antisymmetric *CH\u003csub\u003e3\u003c/sub\u003e. Moreover, two new bands at around 1770 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1915 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be identified as the C\u0026thinsp;=\u0026thinsp;O groups and the produced CO bound to the Cu surface when the operating potential was below \u0026minus;\u0026thinsp;0.8 V vs. RHE. This implies that the H* radical is affected by other products at -0.8 V vs. RHE, which is consistent with the electrochemical test findings. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ef provides the evolution process of the Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs catalyst at different potential conditions. The Cu\u003csub\u003e2\u003c/sub\u003eO clusters were gradually reduced to Cu\u003csup\u003e0\u003c/sup\u003e nanoclusters with the decrease of operated potential, and the Cu\u003csup\u003e0\u003c/sup\u003e nanoclusters supported on r-GO exhibited excellent EtOH and C\u003csub\u003e2+\u003c/sub\u003e production capabilities in electrochemical catalytic CO\u003csub\u003e2\u003c/sub\u003eRR. After testing, Cu\u003csup\u003e0\u003c/sup\u003e nanoclusters were gradually oxidized into Cu\u003csub\u003e2\u003c/sub\u003eO clusters supported on r-GO due to their exposure to air.\u003c/p\u003e \u003cp\u003e \u003cb\u003eTheoretical investigation of Cu\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-CuC\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eO\u003c/b\u003e \u003csub\u003e \u003cb\u003e1\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eClu/GAs on CO\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eRR.\u003c/b\u003e To get the insight of atomic-scale CO\u003csub\u003e2\u003c/sub\u003e reduction mechanism toward the C\u003csub\u003e2+\u003c/sub\u003e product (CH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003eOH, C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e, and CH\u003csub\u003e3\u003c/sub\u003eCOOH) on the asymmetrical Cu\u003csub\u003e4\u003c/sub\u003e-CuC\u003csub\u003e2\u003c/sub\u003eO moiety, we carried out a detailed hydrogenation process study considering the possibility of different intermediates using density functional theory method. Fig. S32 shows the Cu\u003csub\u003e4\u003c/sub\u003e-CuC\u003csub\u003e2\u003c/sub\u003eO configuration in which Cu\u003csub\u003e4\u003c/sub\u003e cluster bonding on the CuC\u003csub\u003e2\u003c/sub\u003eO-graphene. CO\u003csub\u003e2\u003c/sub\u003e molecule can be easily captured on the Cu\u003csub\u003e4\u003c/sub\u003e clusters with the adsorption energy of -0.52 eV in Fig. S33. Figs. S34 and S35 display the optimized models of COOH and CO species. CO intermediate served as a key species to form C\u003csub\u003e2+\u003c/sub\u003e product through CO-CO dimerization, CO-CHO, or CO-COH coupling. Compared with the formed COH intermediate with 1.80 eV adsorption energy, Cu\u003csub\u003e4\u003c/sub\u003e-CuC\u003csub\u003e2\u003c/sub\u003eO was prone to generate the CHO species with lower adsorption energy with \u0026minus;\u0026thinsp;0.45 eV in Fig. S36.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea shows the energy barrier of C-C coupling through the CO-CO and CO-CHO process, corresponding initial state (IS), transition state (TS), and final state (FS) in Figs. S37-S38. The CO-CHO coupling process had lower reaction energy and energy barrier with 0.30 eV and 1.28 eV than that of CO-CO dimerization with 1.81 eV and 2.13 eV. Based on the lower TS barrier, all the primary steps after C-C coupling were studied according to the CO-CHO species. The lowest energy pathways towards the identified CH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003eOH, C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e, and CH\u003csub\u003e3\u003c/sub\u003eCOOH products were illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb, and the optimized models of intermediates were displayed in Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec, S39, and S40. The CH\u003csub\u003e3\u003c/sub\u003eCOOH path ramified at the sixth proton-coupled-electron transfer (PCET) step, while the CH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003eOH and C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e path shared the former eight PCETs, and furcated at the ninth coupled proton-electron-transfer process. The common intermediate for the CH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003eOH and C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e, such as *HCO-CHO (7b), was more superior to form than the intermediates of CH\u003csub\u003e3\u003c/sub\u003eCOOH (7a), indicating the generation of CH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003eOH and C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e before CH\u003csub\u003e3\u003c/sub\u003eCOOH\u003csup\u003e49, 50\u003c/sup\u003e. Free energy analysis further unearthed that the potential-determined step (PDS) of CH\u003csub\u003e3\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003eOH formation was 8b to 9c (*CHOHCHO\u0026rarr;*CH\u003csub\u003e2\u003c/sub\u003eOHCHO) with the free energy change of 0.93 eV, much lower than that of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e with 1.41 eV, which also support the experimental findings.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn summary, we realized the precise adjustment on nano metal size during the formation of unsymmetrical Cu Clu/GAs catalysts by pulsed discharge strategy. A series of Cu Clu/GAs with different cluster sizes (1.4 nm, 1.7 nm, 2.7nm, 4.1nm, 7.5 nm) have been synthesized by adjusting the charging voltage from 7.4 kV to 9.0 kV. Among them, Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs for CO\u003csub\u003e2\u003c/sub\u003eRR including unsymmetrical Cu\u003csub\u003e4\u003c/sub\u003e-CuC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e1\u003c/sub\u003e moieties distributed on GAs were conducted at a charging voltage of 8.6 kV by a transient pulsed discharge strategy. Benefitting from the precise adjustment of the unsymmetrical active moieties, the Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs catalysts performed optimal CO\u003csub\u003e2\u003c/sub\u003eRR activity and stability for EtOH and C\u003csub\u003e2+\u003c/sub\u003e production. The experimental studies and theoretical calculations demonstrated the enhanced electrochemical catalytic performance comes from the optimal unsymmetrical atomic structure and electronic structure feature of the concordantly Cu\u003csub\u003e4\u003c/sub\u003e-CuC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e1\u003c/sub\u003e moieties. This work figures out the problem of balancing the activity and stability of asymmetric structured catalysts and constructs a novel structure-activity relationship in electrochemical catalysis.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eChemicals.\u0026nbsp;\u003c/strong\u003eCopper chloride (CuCl\u003csub\u003e2\u003c/sub\u003e, 99%, Alfa Aesar), Cobalt chloride (CoCl\u003csub\u003e2\u003c/sub\u003e, 99%, Alfa Aesar), Nickel chloride (NiCl\u003csub\u003e2\u003c/sub\u003e, 99%, Alfa Aesar), Hydrogen hexachloroplatinate (H\u003csub\u003e2\u003c/sub\u003ePtCl\u003csub\u003e4\u003c/sub\u003e•xH\u003csub\u003e2\u003c/sub\u003eO, 99.995%,\u0026nbsp;Alfa Aesar), Ruthenium chloride (RuCl\u003csub\u003e2\u003c/sub\u003e, 99%, Alfa Aesar), methanol (analytical grade, Alfa Aesar), KHCO\u003csub\u003e3\u003c/sub\u003e (Sigma Aldrich), Nafion D-521 dispersion (5\u0026nbsp;wt%, Alfa Aesar).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreparation of\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eCu Clu/GAs\u003c/strong\u003e\u003cstrong\u003e.\u0026nbsp;\u003c/strong\u003eIn a typical synthesis, the single-layer graphene oxide (GO) was diluted and mixed fully in deionized water (GO/H\u003csub\u003e2\u003c/sub\u003eO = 2 mg/g). The uniformly dispersed GO was put into a hydrothermal reactor, heated at 180\u0026nbsp;℃\u0026nbsp;for 6 hours, and graphene hydrogel gradually formed. The graphene hydrogel was fully immersed in CuCl\u003csub\u003e2\u003c/sub\u003e aqueous solution for 5 hours, and then quickly frozen in liquid nitrogen. Subsequently, GA support\u0026nbsp;CuCl\u003csub\u003e2\u003c/sub\u003e nanocrystals (CuCl\u003csub\u003e2\u003c/sub\u003e/GA) were formed by freeze-drying.\u0026nbsp;Afterward, the as-prepared CuCl\u003csub\u003e2\u003c/sub\u003e/GA was filled into the copper discharge tube for the pulsed discharge process. Then the discharge tube containing CuCl\u003csub\u003e2\u003c/sub\u003e/GA was connected to the discharge circuit. The discharge voltage could be changed to produce different size metal clusters/nanoparticles supported by GAs. When the air switch is triggered, the intense pulsed current passes through the copper discharge tube and CuCl\u003csub\u003e2\u003c/sub\u003e/GA. The pulsed current and voltage features of Cu\u003csub\u003e1.7\u003c/sub\u003e Clu/GAs and other samples are displayed in\u0026nbsp;Supplementary\u0026nbsp;Note. 1.\u003c/p\u003e\n\u003cp\u003eThe CO\u003csub\u003e2\u003c/sub\u003eRR tests are presented in\u0026nbsp;Supplementary\u0026nbsp;Note. 2, the XAFS measurements and data processing are depicted in\u0026nbsp;Supplementary\u0026nbsp;Notes. 3-5.\u0026nbsp;The\u003cem\u003e\u0026nbsp;in situ\u003c/em\u003e ATR-FTIR test and the details of DFT calculation methods are shown in\u0026nbsp;Supplementary\u0026nbsp;Notes. 6-7.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003e1\u003c/sup\u003e\u003c/strong\u003e\u003cstrong\u003eH Nuclear magnetic resonance analysis.\u003c/strong\u003e The yield of liquid products, such as EtOH, n-PrOH during constant potential electrolysis (4,000 s) were quantified by nuclear magnetic resonance (NMR) spectroscopy\u003csup\u003e16\u003c/sup\u003e. These products were recorded on a Bruker Avance III NMR spectrometer operating at 11.7 T (500 MHz \u003csup\u003e1\u003c/sup\u003eH), and dimethyl sulfoxide (DMSO, 99.9%) was utilized as an internal standard. The same spectral acquisition parameters were used for all spectra to ensure full relaxation and quantification. The acquisition parameters were: time domain data size (65536); number of dummy scans (2); number of scans (16); spectral width (19.9899 ppm); loop count time domain (1); spectral width in Hertz (10,000Hz); filter width (125,000 Hz); pause width (45°); delay 1 (5 s) and delay 2 (0 s). For the NMR tests, a 700 µl electrolyte sample was mixed with 35 µl of internal standard solution (the mixture of 10.0 µl DMSO and 14 ml of D\u003csub\u003e2\u003c/sub\u003eO). Standard curves of each product were obtained by the ratio of relative peak area.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data supporting the findings of this study are available within the article and its Supplementary Information files. All other relevant source data are available from the corresponding authors upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by National Natural Science Foundation of China (Grant No. 12372332, 12002048 and 22375019),\u0026nbsp;the Beijing Natural Science Foundation (Grant No. 2212018), Beijing Institute of Technology Research Fund Program for Young Scholars (Grant No. 2022CX01011 and Grant No. XSQD-202002004), and the Beijing Institute of Technology Research and Innovation Promoting Project (Grant No. 2022YCXZ003). The Start-up Foundation for Senior Talents of Jiangsu University (21JDG041), and the China Postdoctoral Science Foundation (2023M731357). We thank the theoretical calculations performed on A6 Zone of the Beijing Super Cloud Computing Center, supported by PARATERA.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eX.G. and P.C. conceived the idea, designed the research and wrote the paper. K.L. carried out the sample synthesis, characterization and wrote the paper. Z.S. performed CO\u003csub\u003e2\u003c/sub\u003eRR measurement. W.C. carried out the \u003cem\u003ei\u003c/em\u003e\u003cem\u003en situ\u003c/em\u003e synchrotron radiation XAFS measurements and data analysis. Q.Z. revised this paper. H.S., G.L.\u003cem\u003e\u0026nbsp;\u003c/em\u003eand\u003cem\u003e\u0026nbsp;\u003c/em\u003eZ.S. performed the DFT calculations and processed the data. All the authors discussed the results and commented on the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSupplementary information is available for this paper.\u003c/p\u003e\n\u003cp\u003eCorrespondence and requests for materials should be addressed to Z. S., W.C., X.G., or P.C.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLees EW et al (2022) Gas diffusion electrodes and membranes for CO\u003csub\u003e2\u003c/sub\u003e reduction electrolysers. 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Nat Commun 14:6142\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-3991307/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3991307/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePrecisely designing asymmetrical structure is an efficient strategy to optimize the performance of metallic catalysts for electrochemical carbon dioxide reduction reactions. Herein, a transient high-density current induced by pulsed discharge is used to rapidly construct graphene aerogel (GAs) supported asymmetric Cu cluster catalysts. Cu atoms decomposed by CuCl\u003csub\u003e2\u003c/sub\u003e are converged on graphene surfaces in GAs together with oxygen originating from the intense current and instantaneous high temperature. The atomic and electronic structures of Cu nanoclusters exhibit asymmetric distribution due to lattice distortion and O-doping in Cu crystals. Typically, in CO\u003csub\u003e2\u003c/sub\u003e reduction reactions, the selectivity and activity of ethanol are related to the asymmetric structure and strong interfacial interaction of Cu-O/C moieties, exhibiting an ideal Faradaic efficiency (ethanol 75.3% and C\u003csub\u003e2+\u003c/sub\u003e products 90.5%) at -1.1 V \u003cem\u003evs\u003c/em\u003e reversible hydrogen electrode (RHE). Meanwhile, the benefit of the strong interaction between Cu nanoclusters and GA supports, the catalyst exhibits long-term stability. \u003cem\u003eIn situ\u003c/em\u003e XAFS reveals that the Cu\u003csub\u003e4\u003c/sub\u003e-Cu/C\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e1\u003c/sub\u003e interaction displays the effective active sites in CO\u003csub\u003e2\u003c/sub\u003eRR. The pathways of corresponding products and the reaction mechanism on Cu\u003csub\u003e4\u003c/sub\u003e-Cu/C\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e1\u003c/sub\u003e moieties are revealed through the \u003cem\u003ein situ\u003c/em\u003e attenuated total reflectance Fourier transform infrared spectroscopy and the calculation of density functional theory. This work gives a new solution to solve the challenge for balancing the activity and stability of asymmetric-structure catalysts toward energy conversion reactions.\u003c/p\u003e","manuscriptTitle":"Transient Pulsed Discharge Preparation of Graphene Aerogel Supported Asymmetric Cu Cluster Catalysts Promote CO2 Reduction to Ethanol","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-18 07:04:46","doi":"10.21203/rs.3.rs-3991307/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d92f9cd6-fe21-4f12-b49f-e58d1df2c539","owner":[],"postedDate":"March 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":29469235,"name":"Physical sciences/Chemistry/Catalysis/Electrocatalysis"},{"id":29469236,"name":"Physical sciences/Energy science and technology/Carbon capture and storage"}],"tags":[],"updatedAt":"2025-01-31T08:07:48+00:00","versionOfRecord":{"articleIdentity":"rs-3991307","link":"https://doi.org/10.1038/s41467-025-56534-1","journal":{"identity":"nature-communications","isVorOnly":false,"title":"Nature Communications"},"publishedOn":"2025-01-31 05:00:00","publishedOnDateReadable":"January 31st, 2025"},"versionCreatedAt":"2024-03-18 07:04:46","video":"","vorDoi":"10.1038/s41467-025-56534-1","vorDoiUrl":"https://doi.org/10.1038/s41467-025-56534-1","workflowStages":[]},"version":"v1","identity":"rs-3991307","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3991307","identity":"rs-3991307","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}