Electroreduction-Driven Distorted Nanotwins to Activate Pure Cu for Efficient Hydrogen Evolution

Electroreduction-Driven Distorted Nanotwins to Activate Pure Cu for Efficient Hydrogen Evolution | 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 Electroreduction-Driven Distorted Nanotwins to Activate Pure Cu for Efficient Hydrogen Evolution Fang Fang, Zhe Li, Yueshuai Wang, Hui Liu, Xiwen Du, Zhiheng Xie, and 7 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4161916/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 03 Feb, 2025 Read the published version in Nature Materials → Version 1 posted You are reading this latest preprint version Abstract Precious metals like Pt have been favored as catalysts due to their excellent catalytic activity for hydrogen evolution reaction (HER). However, the scarcity and high cost of precious metals have prompted researchers to explore alternative, non-precious metal catalysts. Cu is an attractive candidate for HER due to its plentiful reserves, affordability, and good electrical conductivity. However, Cu shows poor catalytic performance due to its weak binding with intermediates and is generally used as a current collector instead of a catalyst. Herein, the catalytic activity of pure Cu is greatly activated by electroreduction-driven local structure regulation, showing superior HER catalytic performance over commercial Pt/C catalysts at the working current densities greater than 100 mA cm -2 in acid electrolyte. The activation process involved two steps. First, polycrystalline Cu 2 O were prepared by pulsed laser ablation, resulting in abundant grain boundaries within Cu 2 O particles. Next, the Cu 2 O particles were electroreduced to nano pure Cu, inducing the formation of distorted nanotwins and edge dislocations. These local structure regulations introduce strong lattice strain and decrease the Cu coordination number, which enhance the interaction between Cu and intermediates, leading to excellent catalytic activity and durability of pure Cu catalyst. The transformation of non-active nature into high catalytic activity, coupled with the intrinsic low cost, makes pure Cu a promising HER catalyst for large-scale industrial applications. Physical sciences/Materials science/Materials for energy and catalysis/Electrocatalysis Physical sciences/Materials science/Nanoscale materials/Nanoparticles Physical sciences/Chemistry/Catalysis/Electrocatalysis Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Efficient hydrogen evolution through water electrolysis relies on the presence of exceptional catalysts 1-3 . The catalytic performance of catalysts heavily depends on their electronic structure, which could be tuned by local structure regulation 4-6 , such as introducing micro-strain through forming heterogeneous metal interfaces and/or changing the coordination environment by constructing nanostructures 7-11 . Currently, due to the high stability and good intrinsic catalytic activity of noble metals, the regulation strategies of the local structure are mainly applied to noble metal-based catalysts to optimize their electronic structure and thus enhance their catalytic performance 4, 6, 12-15 . However, regardless of the outstanding catalytic activity, the high cost and low abundance of these noble metal catalysts severely limit their wide application 16-18 . Copper (Cu) is considered a potentially ideal catalyst for hydrogen evolution reaction (HER) due to its low cost, high abundance, and excellent electrical conductivity 19-21 . Nevertheless, pure Cu typically exhibits poor HER catalytic activity due to its weak adsorption energy of hydrogen (ΔG H* ), thus it is commonly used as a current collector rather than a catalyst for water electrolysis 4, 22-24 . Following the regulation strategies of local structure for noble metal, the catalytic performance of pure Cu had been improved by introducing 5% tensile strain via plasma spraying 25 . However, the catalytic activity of this sprayed Cu was still far inferior to that of commercial Pt/C. Further enhancing the catalytic performance of pure Cu through increasing strain or coupling with nanostructures is currently unachievable, which is attributed to two primary reasons. Firstly, as the size of Cu particles diminishes, defects formed by local structure regulation are easily absorbed by the surface of nanoparticles, making it difficult for defects to stably exist in low-coordination nano Cu. Secondly, due to a relatively low stacking fault energy (45 mJ m -2 ) 26 , it is prone for Cu to form twin defects with low strain or strain free during the local structure regulation, for instance, rapid quenching, melt-spinning, ball-milling, electrochemical plating, sputtering, severe plastic deformation and so on 27-32 . Therefore, significant challenges remain in activating the HER catalytic activity of pure Cu by introducing strong and stable tensile strains into low coordination nano Cu. In this work, we propose an innovative two-step synthesis strategy to prepare high-efficiency nanocrystalline Cu electrocatalysts with abundant distorted nanotwins (DNTs) for the first time. We start by producing Cu 2 O nanoparticles with numerous grain boundaries through pulsed laser ablation (PLA) in a liquid under oxidizing conditions. Subsequently, electroreduction of the Cu 2 O nanoparticles is employed to rearrange Cu atoms and form pure Cu nanoparticles containing a significant amount of DNTs (referred to as DNTs-Cu). The low atomic coordination number and strong tensile strain within the crystal lattice of DNTs-Cu appropriately enhance the interaction between copper and intermediates. Consequently, DNTs-Cu exhibits high catalytic activity and remarkable catalytic stability, surpassing even commercial Pt/C catalysts at current densities exceeding 100 mA cm -2 , making it the best-performing HER catalyst among all copper-based materials. Distorted nanotwins in Cu nanoparticles The synthesis of DNTs-Cu involved a two-step process, namely PLA plus electroreduction, as illustrated in Fig. 1a . Firstly, the Cu target was ablated in water to yield out-of-order Cu atomic vapor by PLA, and then the Cu atomic vapor was oxidized instantaneously to form copper oxide nanoparticles. The broadened diffraction peaks in X-ray diffraction (XRD) pattern ( Supplementary Fig. 1a ) and the high-resolution transmission electron microscopy (HRTEM) images in Fig. 1b and Supplementary Fig. 2 further prove that the formed copper oxides are polycrystalline Cu 2 O (PC-Cu 2 O) nanoparticles containing many nanocrystalline grains with different orientations. The average particle size of PC-Cu 2 O nanoparticles is 15.2 ± 0.5 nm while the average grain size of nanocrystals is 3.1 ± 0.2 nm ( Supplementary Fig. 1b) . Secondly, PC-Cu 2 O nanoparticles were electroreduced to pure Cu nanoparticles in the neutral electrolyte under -1.2 V vs reversible hydrogen electrode (RHE), as denoted as DNTs-Cu (-1.2 V). The XRD pattern ( Supplementary Fig. 1a ) and the auger electron spectroscopy ( Supplementary Fig. 1c ) demonstrate a complete transformation of Cu 2 O into Cu phase after the electroreduction treatment. Atomic resolution high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) images in Figs. 1c and 1d reveal the presence of a significant number of nanotwins in DNTs-Cu (-1.2 V). Additionally, lots of atomic steps are observed on the surface as marked by the hollow arrows in DNTs-Cu (-1.2 V) in Fig. 1d , suggesting more low coordination Cu atoms on the surface of nanoparticles. Furthermore, three additional electroreduction potentials (-1.4 V, -1.0 V and -0.8 V) were employed to reduce PC-Cu 2 O. The XRD patterns show that the formed DNTs-Cu (-0.8 V), DNTs-Cu (-1.0 V) and DNTs-Cu (-1.4 V) are also pure Cu nanoparticles, as depicted in Supplementary Fig. 3 . The TEM images in Supplementary Figs. 4 - 7 reveal that only a small number of nanotwins are found after electroreduction at -0.8 V, and the density of nanotwins gradually increases as decreasing the reduction potential from -0.8 V to -1.2 V, however, keeps relatively constant when the reduction potential further decreases from -1.2 V to -1.4 V. The evolution trend for the density of nanotwins is consistent with the broadening of XRD peaks in Supplementary Fig. 3 . The local structure of Cu in DNTs-Cu was further investigated by in-situ X-ray absorption spectroscopy (XAS, Supplementary Fig. 8 ). Fig. 1e shows the X-ray absorption near-edge structure spectroscopy (XANES) at Cu K-edge of DNTs-Cu, from which it is clearly revealed that PC-Cu 2 O is reduced to metallic Cu at the reduction voltages lower than -0.8 V according to the shift of the absorption edge from 8981.7 eV for Cu 2 O to 8980.1 eV for Cu as well as the change of the oscillation after absorption edge. After Fourier transformation, the radial distribution functions in Fig. 1f demonstrate that the Cu-Cu bond length in DNTs-Cu nanoparticles is significantly larger than 2.158 Å of the reference Cu foil, and gradually increase with the decrease of reduction potential to 2.185 Å in DNTs-Cu (-0.8 V), 2.211 Å in DNTs-Cu (-1.0 V), 2.255 Å in DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V), respectively. Meanwhile, by least-squares curve fitting of the first shell Cu-Cu bond ( Supplementary Fig. 9 ), the coordination numbers (CNs) of Cu in Fig. 1g also decrease gradually with the decrease of reduction potential from 10.9 in DNTs-Cu (-0.8 V), 10.1 in DNTs-Cu (-1.0 V) to 9.5 in DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V). The increase of Cu-Cu bond length and the decrease of CNs provide evidences that the local structure of Cu could be effectively regulated by the designed two-step preparation. Local structure analyses of DNTs-Cu DNTs-Cu (-1.2 V) served as the representative sample, and its local structure was further analyzed using HRTEM technique, as depicting in Fig. 2 . From Fig. 2a , we could observe that Cu nanograins are interconnected in the form of fourfold or fivefold twins, which indicate the existence of tensile strain in face-centered cubic metals 33, 34 . The FFT pattern crossing the twin boundary between Twin 1 and Twin 2 in Fig. 2b confirms the distinct tensile strains within these nanotwins (similar results shown in Supplementary Fig. 6 ). For instance, in Fig. 2c , the atom distance along [1 2] was measured to be 0.229 nm in line 1, which is different from the one along [112] of 0.242 nm in line 2. As compared with the standard atom distance of perfect Cu (0.222 nm along direction), the increased atom distances in these two different [1 2] and [112] directions of Twin 1 indicate the existence of lattice tensile strain of 3.1% and 9.0%, respectively, resulting in an average lattice tensile strain approximately being 6%. However, Twin 3 ( Fig. 2a ) with a few numbers of atomic layers exhibits a totally different lattice strain state, in which the intersection angles between the lattice planes (111) and (1 1) change from 73.7° to 77.1° ( Figs. 2d and 2e ), both are larger than the one of perfect Cu structures with 70.5°. It is notable that, the closer distance to the core of fivefold twin, the greater the deviation of the angle between (111) and (1 1) plane, which indicates that Twin 3 suffers a larger tensile strain but the strain distribution is not uniform. Additionally, geometric phase analyses (GPA) of this sample in Fig. 2h show that axial strain (ɛ xx , ɛ yy ) and shear strain (ɛ xy ) are distributed differently in various twin regions, which could reach a maximum value of ~10%. Furthermore, the edge dislocations with low CN at the twin boundary and the grain interior are observed ( Figs. 2f and 2 g ), which accompanies the electroreduction process from Cu 2 O to Cu 35-37 . Atomic resolution electron tomography (AET) was utilized to further obtain the three-dimensional (3D) atomic structures of DNTs-Cu (-1.2 V) 38 . 3D volume of a small DNTs-Cu nanoparticle was computed by reconstructing a tomographic tilt series by an algorithm reported elsewhere 39, 40 ; and the 3D atomic coordinates of individual atoms were traced to produce an experimental atomic model of DNTs-Cu nanoparticle (Methods, Supplementary Figs. 10 and 11 ). From the experimental 3D coordinate, we quantitatively analyzed the coordination number (CN), bond length and 3D tensile strain at atomic resolution. As shown in Figs. 3a and 3b , the nanoparticle contains complicated structures including nanotwin and dislocation. The intersection angle between the lattice planes (111) and (1 1) varies from 74.2° in domain 1 to 69.2° in domain 2, revealing a significantly different lattice strain, which is consistent with previous two-dimensional structure analysis in Fig. 2 . The CN of the surface atoms show that there are numerous atoms with low coordination in DNTs-Cu (-1.2 V), and the CNs of some atoms could even be reduced to 4 or 5 ( Fig. 3c ), which may derive from the atomic step caused by rearrangement of Cu atom during electroreduction. Radial distribution function (RDF, Fig. 3d ) plots of all three nanotwins reveal that the overall Cu-Cu bond lengths become longer, particularly in domain 3, indicating a strong lattice expansion of DNTs-Cu, which agrees with the results of EXAFS and HRTEM analyses in Fig. 1f and Fig. 2 . Furthermore, the 3D displacement field and full strain tensor analyses of the atomic slices in Figs. 3f-3j and Supplementary Fig. 12 show that the strong shear strain in Z direction (ɛ zz , ɛ xz , ɛ yz ) introduces significant tensile strain, and the maximum tensile strain reaches up to ~10% as shown in Figs. 3f-3j and Fig. 2c . According to the DFT calculations in Supplementary Figs. 13 - 17, with the increase of tensile strain and the reduction of coordination number, the number of electrons shared between Cu atoms would decrease, leading to an upshift of d-band center and a decrease of ΔG H* . In particular, when the coordination number decreased to 5 while a 6% tensile strain was introduced, the ΔG H* of Cu(111)/(110) surface approaches an optimized value close to zero, indicating that fantastic HER catalytic performance. Therefore, due to the ability to measure the strain and coordination number of each atom based on the 3D experimental model, the structural information of Cu atoms at the surface could be separated and studied in detail. As shown in Figs. 3e and 3k , numerous surface Cu atoms exhibit tensile strain and low coordination, and even part of surface atoms show high tensile strain (≥ 6%) and very low coordination number (≤ 5), which are recognized as active sites in DFT. Moreover, electron holography experiment was carried out to visually map out the local electric field and charge density distribution in DNTs-Cu (-1.2 V). The charge distribution map in Supplementary Fig. 18 clearly demonstrates that many electron-deficient regions segregate at the surface and twin boundaries of the DNTs-Cu nanoparticles, indicating that the low CN and strained Cu atoms at the surface of nanoparticles are with electron-deficient state and very likely to act as the highly active HER catalytic sites. Excellent HER activity and durability of DNTs-Cu The HER properties of DNTs-Cu catalysts were evaluated in a standard three-electrode system at room temperature, using RHE calibration without insulation resistance compensation ( Supplementary Figs. 19 - 22 ). For comparison, monocrystal Cu nanoparticles (5.95±0.2 nm in diameter, marked as MC-Cu in Supplementary Fig. 23 ) and Cu film (~50 nm in thickness in Supplementary Fig. 24 ) have also been prepared and tested. As shown in Figs. 4a , 4b and Supplementary Fig. 25 , HER activities of DNTs-Cu, which are significantly better than that of MC-Cu and Cu film, gradually enhance with the decrease of electroreduction potential from -0.8 V to -1.2 V. When the electroreduction potential was further reduced to -1.4 V, the HER performance of DNTs-Cu (-1.4 V) becomes quite similar with that of DNTs-Cu (-1.2 V) as displayed in Supplementary Fig. 26 . For instance, at a current density of 10 mA cm -2 , the overpotential distinctly decreases from 632 mV for Cu foam, 589 mV for Cu film, 441 mV for MC-Cu, 287 mV for DNTs-Cu (-0.8 V), 170 mV for DNTs-Cu (-1.0 V) to 61 mV for DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V). Since the curve overlapping for DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V), the HER properties of DNTs-Cu (-1.4 V) were removed in Fig. 4 for clearer illustration. Compared with Pt/C, DNTs-Cu (-1.2 V) presents nearly comparable HER performance at the small current density of 10 mA cm -2 ( Figs. 4a and 4b ). However, when the current density increases to greater than 100 mA cm -2 , the HER performance of DNTs-Cu (-1.2 V) significantly surpasses that of Pt/C as shown in Fig. 4c . For example, at 500 mA cm -2 , the overpotentials of DNTs-Cu (-1.2 V) is 301 mV, which is significantly lower than 425 mV for Pt/C, suggesting a greater potential for industrial applications of DNTs-Cu (-1.2 V) 41, 42 . To explore the intrinsic activity of catalysts, the exchange current densities ( j 0 ) were calculated using the Tafel formula. As shown in Fig. 4d , the j 0 of DNTs-Cu also enhances along with the decrease of electroreduction potential, and the highest j 0 of 1.1 × 10 -3 A cm -2 is found for DNTs-Cu (-1.2 V), which is twice as much as that of 5.5 × 10 -4 A cm -2 for Pt/C. Compared to the theoretical value, the high j 0 of DNTs-Cu (-1.2 V) moves Cu from the bottom up to the top of volcano plots, achieving an intrinsic activity superior to that of Pt. Meanwhile, the HER activity of DNTs-Cu (-1.2 V) has been also compared with other well-developed Cu-based catalysts. The comparison results in Fig. 4e and Supplementary Table 1 convince that DNTs-Cu (-1.2 V) exhibits much higher catalytic activity than all other Cu-based catalysts reported so far, even better than some noble metal-Cu alloys. To further validate the origin of the excellent HER activity of DNTs-Cu, DNTs-Cu (-1.2 V) was annealed under vacuum condition to remove DNTs. The annealed sample was denoted as annealed-DNTs-Cu (-1.2 V) as shown in Supplementary Fig. 27 and its HER performance was investigated. After annealing, the XRD peaks of annealed-DNTs-Cu (-1.2 V) narrowed ( Supplementary Fig. 28 ), indicating an enhancement in crystallinity. The SEM and TEM characterizations reveal that the nanoparticle size is basically unchanged, but the DNTs in annealed-DNTs-Cu (-1.2 V) have almost completely disappeared and the lattice has been restored to a perfect Cu lattice without any tensile distortion, as shown in Supplementary Figs. 29 and 30. The XAS results of annealed-DNTs-Cu (-1.2 V) in Supplementary Fig. 31 demonstrate that the Cu-Cu bond length shortens to 2.161 Å and CN increases to 11.6, further confirming the elimination of tensile strain and crystal defects due to annealing. Meanwhile, the HER performance in Supplementary Fig. 32 shows that the overpotential increases from 61 mV to 543 mV and the Tafel slope also raises from 33 mV/dec to 227 mV/dec for DNTs-Cu (-1.2 V) and annealed-DNTs-Cu (-1.2 V), respectively. This severe degradation in catalytic performance in turn demonstrates that the excellent HER performance in DNTs-Cu (-1.2 V) originates from the synergistic effect of the low CN and strong tensile strain. In addition, the catalytic durability of DNTs-Cu (-1.2 V) is investigated and the results are shown in Fig. 4f and 4g . After an accelerated durability test (ADT) of 5000 cycles, no obvious change of the polarization curve can be observed for DNTs-Cu (-1.2 V), however, a serious deterioration is detected for Pt/C, which makes the HER performance after ADT of Pt/C far inferior to that of DNTs-Cu (-1.2 V). Moreover, as illustrated in Fig. 4h , after 125 h of continuous i - t testing at a huge current density of 500 mA cm -2 , the current density of DNTs-Cu (-1.2 V) merely decreases by ~2%, meanwhile the morphology and the local structure of DNTs-Cu remains unchanged in Supplementary Figs. 33 - 35. In contrast, the current density of commercial Pt/C drops by ~46% only after 14 h continuous measurement (the inset of Fig. 4h ). Key role of grain boundaries in PC-Cu2O The phase transformation from Cu 2 O to Cu by electroreduction was widely used for carbon dioxide reduction reaction (CRR). Interestingly, no DNTs have been observed in electroreduction-derived Cu during CRR 43-46 . A comprehensive comparison between the CRR electroreduction process and our experiment suggests that the high density of grain boundaries in PC-Cu 2 O may be a critical factor in DNTs formation. For the PC-Cu 2 O nanoparticles composed of ~3 nm Cu 2 O nanograins, the applied negative reduction potential would preferentially trigger the rapid transition from Cu 2 O lattice into Cu lattice at the abundant grain boundary sites, because the Cu diffusion energy barrier of 0.22 - 0.31 eV at the grain boundaries is much smaller than 0.57 - 0.64 eV for O-vacancy assistant bulk Cu diffusion 35 . Meanwhile, considering that the transition from Cu 2 O into Cu has strictly crystal plane inheritance of Cu 2 O(110)/Cu(110) and Cu 2 O(100)/Cu(100) 35 , the rapid reduction of PC-Cu 2 O at grain boundaries simultaneously yields a large number of Cu nanocrystals with different orientations. As these crystals amalgamate, the mismatches at the interfaces necessitate substantial lattice matching adjustments in the epitaxially transformed Cu lattice, thereby inducing high tensile strain. With the increase of the electroreduction potential from -0.8 V to -1.2 V, the kinetics of the whole electroreduction processes are accelerated. This acceleration reduces the time available for lattice matching adjustments and prevents the dissipation of stress and strain, and as a result, more stress and strain are stored in DNTs-Cu (-1.2 V) ( Supplementary Figs. 4 - 7 ) 33, 47 . To further investigate the influence of grain boundaries, PC-Cu 2 O was annealed to eliminate grain boundaries, resulting in the formation of monocrystalline Cu 2 O nanoparticles of comparable size ( Supplementary Fig. 36 ). These monocrystal Cu 2 O nanoparticles were then subjected to electroreduction at -1.2 V under the same reduction conditions to produce Cu nanoparticles as shown in Supplementary Fig. 37 . This formed sample was denoted as Annealed-PC-Cu (-1.2 V). Consistent with the reports for CRR, no obvious DNTs were identified in Annealed-PC-Cu (-1.2 V). The corresponding HER activity shows that the overpotential at 10 mA cm -2 and Tafel slope of Annealed-PC-Cu (-1.2 V) were 390 mV and 176 mV/dec, respectively, which are comparable to 441 mV and 204 mV/dec for MC-Cu but are significantly higher than 61 mV and 33 mV/dec for DNTs-Cu (-1.2 V). Therefore, it can be concluded that the presence of numerous grain boundaries and extremely small grain sizes in PC-Cu 2 O are critical prerequisites for the formation of DNTs. All these results suggest that during the rapid electroreduction process from Cu 2 O to Cu, the abundant grain boundaries of the initial PC-Cu 2 O trigger the simultaneous formation of multiple crystallographic orientation of Cu in each nanoparticle, which promotes the formation of multiple nano-twinned structures and locks up the localized lattice distortion strains with various crystal defects. To demonstrate the general versatility of electroreduction-driven local structure regulation, polycrystalline Ag 2 O nanoparticles with a large number of nanocrystalline grains were prepared and electroreduced under -1.2 V ( Supplementary Fig. 38 ). As excepted, abundant distorted nanotwins could be clearly observed in pure Ag ( Supplementary Figs. 39 - 41 ) and result in a significant improvement of the HER activity of Ag ( Supplementary Fig. 42 ). Conclusions In summary, a highly active and stable pure Cu catalyst was successfully prepared and its fantastic HER performance was investigated for the first time. Cu 2 O nanoparticles with abundant grain boundaries were firstly prepared by PLA and then were electroreduced to form DNTs-Cu. Systematic experiments and calculations demonstrated that a strong tensile strain was introduced in DNTs-Cu and the CN of Cu was significantly decreased, resulting in an enhancement of the adsorption capacity of Cu for catalytic intermediate H * . As anticipated, DNTs-Cu demonstrates remarkable HER catalytic performance in acid conditions, even better than commercial Pt/C under the high working current density. The approach of DNTs formation in metals via electroreduction as well as the principle of tuning ΔG H* by changing coordination number and tensile strain have been validated to be powerful strategies for activating HER catalysis of metals that are typically non-active. Methods Reagents and Materials. Copper target (99.99%), copper foil (99.99%) and copper foam (99.99%) were purchased from Tianjin Incole Union Technology Co., Ltd. Potassium bicarbonate (KHCO 3 ) was purchased from Aladdin (Shanghai). Commercial Pt/C (20 wt%) catalyst was purchased from Johnson Matthey. Nafion solution (5 vol%) was purchased from Dupont. All chemical reagents were used as received without further purification. Synthesis of PC-Cu 2 O nanoparticles. The PC-Cu 2 O nanoparticles were prepared by pulsed laser ablation of Cu target in deionized water using a nanosecond pulsed Nd:YAG laser (Nimma-600, Beamtech) with the spot diameter about 2 mm at the pulse width of 7 ns, the wavelength of 1064 nm, the frequency of 15 Hz and the energy of 500 mJ. Before the laser ablation, the Cu target (20 mm in diameter and 5 mm in thickness) was polished and washed by diluted hydrochloric acid to remove the oxide layer. The target was placed in a 100 ml beaker containing deionized water with its upper surface 10 mm from the water surface, then ablated for 30 min to get the colloidal solution containing PC-Cu 2 O nanoparticles. In the ablation process, the breaker was placed in ice bath. Then the colloidal solution was enriched by a high-speed centrifuge (19000 rpm, 20 min, 10 °C, SIGMA-3K30), and then vacuum freeze-dried (Biocool-FD-1-50) to obtain the PC-Cu 2 O nanoparticles powder. Preparation of DNTs-Cu. Typically, 50 mg PC-Cu 2 O nanoparticles was suspended in 5 ml isopropanol, 5ml deionized water and 5 µl Nafion solution (5 wt.%, Du Pont) to form a homogeneous ink assisted by ultrasound. Then the homogeneous ink was spread onto the surface of Cu foam by air brush and dried under room temperature. The electrochemical reduction of PC-Cu 2 O to prepare DNTs-Cu electrode was performed under atmospheric conditions in Ar-saturated 0.1 M KHCO 3 aqueous solution (pH 6.8) using a standard three-electrode electrolysis cell. A PC-Cu 2 O@Cu foam electrode was used as working electrode. The counter and reference electrodes were a graphite rod and a KCl-saturated Hg/Hg 2 Cl 2 electrode respectively. The electrochemical reduction was performed at the potential of -0.8 V, -1.0 V, -1.2V and − 1.4 V ( vs. RHE) for 30 min to get DNTs-Cu (-0.8 V), DNTs-Cu (-1.0 V), DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V) electrode, respectively. The DNTs-Cu electrodes were washed by deionized water under Ar protection and dried in vacuum drier. Preparation of MC-Cu and Cu film. The MC-Cu was prepared by magnetron sputtering (LEICA EM SCD 500) under vacuum using Cu foam as substrate. The electric current of magnetron sputtering is 100 mA and sputtering time is 100 s. The Cu film electrode was prepared by thermal evaporation (oerlikon UNIVEX 250) under vacuum using Cu foam as substrate. The electric current of thermal evaporation is 140 A. Annealing of DNTs-Cu (-1.2 V) and PC-Cu 2 O. The annealing of DNTs-Cu (-1.2 V) was carried out in a tube furnace with Ar protection under 400 °C for 2h. The annealing of PC-Cu 2 O nanoparticles was carried out in a tube furnace with Ar protection under 400 °C for 5h. Materials characterizations. The TEM images were taken on a JOEL 2100F transmission electron microscope. The SEM images were taken on a Hitachi S-4800 scanning electron microscope. HAADF-STEM was performed using a JEOL ARM200F microscope with the STEM aberration corrector operated at 200 kV and spherical aberration correction TEM of ETEM (Thermofisher) with accelerated voltage of 300 kV. The convergent semiangle and collection angle for HAADF acquisition were 21.5 and 200 mrad, respectively. The aberration coefficient (C s ) used was equal to 1 µm. Geometric-phase analysis to obtain the strain information on the surface of DNTs-Cu (-1.2 V) was conducted with Digital Micrograph software. The X-ray diffraction with Cu Kα radiation as the radiation source through a Ni filter (Bruker D8 Advanced) was used to determine the crystalline structure of the catalysts. In situ XAS measurements were operated at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility (SSRF). All of XAFS data were recorded during one period of beam time. The acquired XAFS data were analyzed by Athena and Artemis software according to the standard procedures. The charge distribution map was performed using JEOL 2100F transmission electron microscope. Auger electron spectroscopy was measured by a THERMO SCIENTIFIC ESCALAB 250Xi. Tomographic tilt series with a tilt range of from − 76° to + 69° with the increment of 2 to 3 o for a DNTs-Cu nanoparticle was acquired on an aberration-corrected microscope operated at 300 kV with a screen current of 20pA. Three sequential images were obtained with a dwell time of 2 µs in each tilt angle to minimize sample drift. After image denoising, background subtracting and alignment, 3D reconstruction was computed from the tilt series using an iterative algorithm 48 . All the 3D atom coordinates were determined by identifying all the local maxima and locating the peak positions using polynomial fitting in the 3D reconstruction. Using the ideal fcc structure as the best-fit lattice 49 , we calculated the atomic displacement field based on the 3D coordinates of the individual atoms. A 3.4-Å-wide Gaussian kernel is convolved with the displacement field to reduce the noise. The 3D strain tensor is then calculated by differentiation of the displacement field. Electrochemical measurements. The HER electrochemical measurements were performed in Ar-saturated 0.5 M H 2 SO 4 aqueous solution in a standard three-electrode electrolysis cell using prepared DNTs-Cu (Cu film, MC-Cu)@Cu foam electrode as the working electrode, a graphite rod as the counter electrode and a KCl-saturated Hg/Hg 2 Cl 2 electrode as the reference electrode. The commercial Pt/C@Cu foam electrode was also prepared as DNTs-Cu@Cu foam electrode and the final loading of catalysts on work electrode is 0.4 mg cm − 2 . The 0.5 M H 2 SO 4 solution was purged with Ar for about 60 min to exclude air. All the electrochemical measurements including cyclic voltammetry (CV), linear sweep voltammetry (LSV), current-time (i-t) and electrochemical impedance spectroscopy (EIS) were performed by the electrochemical workstation CHI660E. The Polarization curves under high potential were performed by the electrochemical workstation CHI1140C. Before each polarization curve test, 100 cycles of CVs were swept at a scan rate of 50 mV s − 1 to stabilize the catalysts. The LSVs were recorded by a scan rate of 5 mV s − 1 . All potentials were calibrated with respect to reversible hydrogen electrode (RHE) in the hydrogen-saturated electrolyte with Pt sheets as working electrode. Computational methods. The DFT computation were performed using the Vienna ab initio simulation package (VASP) with the exchange correction function described by the generalized gradient approximation (GGA) within the Perdew-Burke-Ernzerhof (PBE). A plane wave basis was set to a cutoff energy of 450 eV. For structure relaxations, the convergence criteria were set to less than 0.03 eV/Å and 1×10 − 5 eV. The Cu surface was modelled with a 3×3 unit cell and a four-layer slab, with the bottom two layers fixed. The vacuum layer was set to 15 Å. The Gibbs free energy of hydrogen adsorption is based on the computational hydrogen electrode (CHE) model from ΔG = ΔE DFT + ΔE ZPE - TΔS , where ΔE DFT , ΔE ZPE and ΔS correspond to the change of the calculated energy, zero point energy, and entropy at room temperature. According to the previous study, the free energy of hydrogen adsorption were calculated as ΔG = ΔE DFT + 0.24 eV. The differential charge density is used to reflect the electron transfer between Cu atoms, of which the positive value represents electron enrichment and the negative value represents electron loss. For metals, because the outer electrons are weakly bound by the nucleus, they often break away and become free electrons. Free electrons are shared between metal atoms, so the differential charge density between metal atoms is positive, while the internal is negative. Declarations Data availability All relevant data are available from the corresponding author upon reasonable request. Acknowledgements The work at Fudan University was financially supported by National Key R&D Program of China (2020YFA0406204), National Natural Science Foundation of China (No. 52071083, 51922031, 12074016, 12274009 and 22172003), Science & Technology Commission of Shanghai Municipality (No. 20XD1420600), China Postdoctoral Science Foundation (No. BX2021066, 2021M700024), Zhuhai Fudan Innovation Institute, Beijing Natural Science Foundation (Z210016), the General Program of Science and Technology Development Project of Beijing Municipal Education Commission (KM202110005003) and the Research and Development Project from the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering (2022SX-TD001). The authors thank Renchao Che from Fudan university for charge distribution test. The authors thank the Electron Microscopy Laboratory at Peking University for the use of aberration-corrected electron microscopes and the High-performance Computing Platform of Peking University. Competing interests The authors declare no competing interests. Author Contributions D. Sun and F. Fang conceived the experiments and supervised the project. Z.Li and Y. Wang designed and conducted the experiments. Z. Li, H. Liu. and F. Wang performed the experimental data analysis. Z. Li, Y. Lu and F.F. wrote the paper. Y. Wang, Y. Lu and M. Sui performed atomic-scale TEM measurements and analyzed the data. J. Zhou and Z. Xie performed atomic resolution electron tomography experiment and 3D structural analysis. X. Du M. Sui and D. Sun contributed the experimental platform. All authors discussed the results and commented on the manuscript. Additional information Supplementary information is available in the online version of this paper. Reprints and permissions information is available at www.nature.com/reprints. Correspondence and requests for materials should be addressed to Jihan Zhou, Yue Lu, Dalin Sun and Fang Fang. 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J Am Chem Soc 144:259–269 Zhu Q et al (2022) Hierarchical twinning governed by defective twin boundary in metallic materials. Sci Adv 8:eabn8299 Yang Y et al (2021) Determining the three-dimensional atomic structure of an amorphous solid. Nature 592:60–64 Xu R et al (2015) Three-dimensional coordinates of individual atoms in materials revealed by electron tomography. Nat Mater 14:1099–1103 Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryInformation.docx Cite Share Download PDF Status: Published Journal Publication published 03 Feb, 2025 Read the published version in Nature Materials → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-4161916","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":294348954,"identity":"c716eeab-cbaf-4347-b07d-717d8b5f12c7","order_by":0,"name":"Fang 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1","display":"","copyAsset":false,"role":"figure","size":553407,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePreparation and Characterization of DNTs-Cu catalysts.\u003c/strong\u003e \u003cstrong\u003ea,\u003c/strong\u003e Schematic illustration of the synthesis and crystal structure of DNTs-Cu catalyst. \u003cstrong\u003eb,\u003c/strong\u003e High resolution TEM (HRTEM) image of PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticle. The colored areas represent nanocrystalline grains of Cu\u003csub\u003e2\u003c/sub\u003eO. The inset is a selected area electron diffraction pattern. \u003cstrong\u003ec\u003c/strong\u003e, Atomic resolution aberration-corrected HAADF-STEM image of DNTs-Cu (-1.2 V) catalyst. The white lines represent nanotwins.\u003cstrong\u003e d,\u003c/strong\u003e The HAADF-STEM image of DNTs-Cu (-1.2 V) catalyst. The white lines represent nanotwins and the arrows represent the atomic steps. \u003cstrong\u003ee,\u003c/strong\u003e In situ XANES spectra of PC-Cu\u003csub\u003e2\u003c/sub\u003eO under different electroreduction potential and reference sample at Cu K-edge (Inset, magnified pre-edge XANES region). \u003cstrong\u003ef,\u003c/strong\u003e The radial distribution functions of DNTs-Cu catalysts and Cu foil. \u003cstrong\u003eg,\u003c/strong\u003e The fitted CNs of DNTs-Cu catalyst and Cu foil.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-4161916/v1/41a8d004afb64400d8d0af74.png"},{"id":55204058,"identity":"6361a710-acfe-4223-9b6b-cb566831a8fe","added_by":"auto","created_at":"2024-04-24 03:47:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1081437,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnalyses on the origin of lattice strain in DNTs-Cu.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e, Spherical aberration corrected HRTEM image of DNTs-Cu (-1.2 V) catalyst, the twin boundary (TB) is labeled along white line. \u003cstrong\u003eb,\u003c/strong\u003e FFT pattern across the Twin 1 (white markers) and Twin 2 (yellow markers) in (a). The lattice strains and angles between the (111) and (111¯) lattice planes are measured and marked in this image. \u003cstrong\u003ec\u003c/strong\u003e, Lattice distance scanning along Line 1 and Line 2 in (a), the tensile strain is calculated as compared with the one of standard Cu lattice. \u003cstrong\u003ed,\u003c/strong\u003e \u003cstrong\u003ee,\u003c/strong\u003e Enlarged HRTEM images from areas ②and ① in Twin 3 of (a), the angles between two {111} planes are 73.7° and 77.1° respectively. \u003cstrong\u003ef,\u003c/strong\u003e \u003cstrong\u003eg,\u003c/strong\u003eMagnified HRTEM images from green and yellow box areas in (a), the edge dislocations are labeled with the yellow arrows. \u003cstrong\u003eh,\u003c/strong\u003e Geometric-phase analysis (GPA) of the HRTEM images in (a).\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-4161916/v1/fdc27d3490986b493a11be88.png"},{"id":55204196,"identity":"538ec8df-db9a-4018-b37b-36e8e3262a27","added_by":"auto","created_at":"2024-04-24 03:55:07","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":517780,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e3D atomic structure and 3D strain tensor measurements in a DNTs-Cu particle.\u003c/strong\u003e \u003cstrong\u003ea-b, \u003c/strong\u003e3D atomic model of DNTs-Cu (-1.2 V), view from [10] (\u003cstrong\u003ea\u003c/strong\u003e) and [11] (\u003cstrong\u003eb\u003c/strong\u003e) zone axis, that shows three domains containing twin boundaries and dislocation (marked with orange color). \u003cstrong\u003ec,\u003c/strong\u003e CN of all atoms was identified from the coordinates of DNTs-Cu (-1.2 V) particle. The CNs of the surface atoms in the nanoparticle are low (the front, back and the surfaces of domain 3 are actual exposed surface of this particle).\u003cstrong\u003e d, \u003c/strong\u003eRadial distribution function (RDF) plots calculated from the atomic coordinates of domain 1, 2, 3 in (a), red lines indicate the standard peak location of monocrystal Cu.\u003cstrong\u003e e,\u003c/strong\u003e The normalized distribution plot for strain tensor (ɛ\u003csub\u003eyz\u003c/sub\u003e) of surface atoms with CN less than 9. \u003cstrong\u003ef,\u003c/strong\u003e Individual atoms in eight successive 2-atom-thick slices, where some surface and boundary atoms in red are excluded for displacement field and strain measurements. (\u003cstrong\u003eg\u003c/strong\u003e) lattice displacement maps in [001] direction (z axis), obtained by convolving the 3D atomic displacements with a 3.4-Å-wide 3D Gaussian kernel to reduce the noise. (\u003cstrong\u003eh-j\u003c/strong\u003e) Maps of the three components of the full strain tensor along zz (\u003cstrong\u003eh\u003c/strong\u003e), xz (\u003cstrong\u003ei\u003c/strong\u003e) and yz (\u003cstrong\u003ej\u003c/strong\u003e) planes. The 3D lattice displacement field and all six components of full strain tensor are shown in Supplementary Fig 12. \u003cstrong\u003ek,\u003c/strong\u003e The yz shear statistic of each atom with different coordination numbers from 5 to 9.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-4161916/v1/ead26a3bc3e55feff28ed00d.png"},{"id":55203825,"identity":"aa10b585-5467-4b9b-9513-7375fdde4e9b","added_by":"auto","created_at":"2024-04-24 03:39:07","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":747469,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHER activity and durability of different catalysts in Ar-saturated 0.5 M H\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eSO\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e aqueous electrolyte.\u003c/strong\u003e \u003cstrong\u003ea,\u003c/strong\u003e Polarization curves of DNTs-Cu (-1.2 V), DNTs-Cu (-1.0 V), DNTs-Cu (-0.8 V), MC-Cu, Cu film and commercial Pt/C with scan rate of 5 mV s\u003csup\u003e-1\u003c/sup\u003e, without \u003cem\u003eiR\u003c/em\u003e compensation. \u003cstrong\u003eb,\u003c/strong\u003e Corresponding Tafel plots of the polarization curves in (\u003cstrong\u003ea\u003c/strong\u003e). \u003cstrong\u003ec,\u003c/strong\u003e The Polarization curves of DNTs-Cu (-1.2 V) and commercial Pt/C under high potential for HER. \u003cstrong\u003ed,\u003c/strong\u003e The exchange current density (\u003cem\u003ej\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e) of DNTs-Cu (-1.2 V), DNTs-Cu (-1.0 V), DNTs-Cu (-0.8 V), MC-Cu, Cu film and commercial Pt/C. The volcano plots of \u003cem\u003ej\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e as a function of the ΔG\u003csub\u003eH*\u003c/sub\u003e for pure metals is shown to guide the eye for HER activity comparison. Polarization curves of L-Ag before and after 5000 CV cycles. \u003cstrong\u003ee,\u003c/strong\u003e The HER activity comparison between DNTs-Cu (-1.2 V) and recently reported representative Cu-based HER electrocatalysts. The blue area is shown to guide the eye for pure Cu HER catalysts. \u003cstrong\u003ef, \u003c/strong\u003ePolarization curves of DNTs-Cu (-1.2 V) before and after 5000 CV cycles. \u003cstrong\u003eg, \u003c/strong\u003ePolarization curves of commercial Pt/C before and after 5000 CV cycles. \u003cstrong\u003eh,\u003c/strong\u003e Current-time (i-t) chronoamperometric response of DNTs-Cu (-1.2 V) and commercial Pt/C (inset) under the overpotential of 500 mA cm\u003csup\u003e-2\u003c/sup\u003e, the oscillation of curve is due to the loss of counter electrode (GR, graphite rod) and the replacement of GR.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-4161916/v1/49cd7bacc8dc87ad0c60ab47.png"},{"id":75402015,"identity":"52908fcf-09bf-4db4-9a4f-cbae2519086a","added_by":"auto","created_at":"2025-02-04 08:08:01","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4194051,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4161916/v1/14736c12-f0a1-4468-9df8-2a4e45b2fede.pdf"},{"id":55203827,"identity":"526f10a2-8392-4d14-9186-8aaa88f838c5","added_by":"auto","created_at":"2024-04-24 03:39:07","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":7437496,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-4161916/v1/e261bab2d7fcf06b0679f53d.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Electroreduction-Driven Distorted Nanotwins to Activate Pure Cu for Efficient Hydrogen Evolution","fulltext":[{"header":"Introduction","content":"\u003cp\u003eEfficient hydrogen evolution through water electrolysis relies on the presence of exceptional catalysts\u003csup\u003e1-3\u003c/sup\u003e. The catalytic performance of catalysts heavily depends on their electronic structure, which could be tuned by local structure regulation\u003csup\u003e4-6\u003c/sup\u003e, such as introducing micro-strain through forming heterogeneous metal interfaces and/or changing the coordination environment by constructing nanostructures\u003csup\u003e7-11\u003c/sup\u003e. Currently, due to the high stability and good intrinsic catalytic activity of noble metals, the regulation strategies of the local structure are mainly applied to noble metal-based catalysts to optimize their electronic structure and thus enhance their catalytic performance\u003csup\u003e4, 6, 12-15\u003c/sup\u003e. However, regardless of the outstanding catalytic activity, the high cost and low abundance of these noble metal catalysts severely limit their wide application\u003csup\u003e16-18\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eCopper (Cu) is considered a potentially ideal catalyst for hydrogen evolution reaction (HER) due to its low cost, high abundance, and excellent electrical conductivity\u003csup\u003e19-21\u003c/sup\u003e. Nevertheless, pure Cu typically exhibits poor HER catalytic activity due to its weak adsorption energy of hydrogen (\u0026Delta;G\u003csub\u003eH*\u003c/sub\u003e), thus it is commonly used as a current collector rather than a catalyst for water electrolysis\u003csup\u003e4, 22-24\u003c/sup\u003e. Following the regulation strategies of local structure for noble metal, the catalytic performance of pure Cu had been improved by introducing 5% tensile strain via plasma spraying\u003csup\u003e25\u003c/sup\u003e. However, the catalytic activity of this sprayed Cu was still far inferior to that of commercial Pt/C. Further enhancing the catalytic performance of pure Cu through increasing strain or coupling with nanostructures is currently unachievable, which is attributed to two primary reasons. Firstly, as the size of Cu particles diminishes, defects formed by local structure regulation are easily absorbed by the surface of nanoparticles, making it difficult for defects to stably exist in low-coordination nano Cu. Secondly, due to a relatively low stacking fault energy (45 mJ m\u003csup\u003e-2\u003c/sup\u003e)\u003csup\u003e26\u003c/sup\u003e, it is prone for Cu to form twin defects with low strain or strain free during the local structure regulation, for instance, rapid quenching, melt-spinning, ball-milling, electrochemical plating, sputtering, severe plastic deformation and so on\u003csup\u003e27-32\u003c/sup\u003e. Therefore, significant challenges remain in\u0026nbsp;activating the HER catalytic activity of pure Cu by introducing strong and stable tensile strains into low coordination nano Cu.\u003c/p\u003e\n\u003cp\u003eIn this work, we propose an innovative two-step synthesis strategy to prepare high-efficiency nanocrystalline Cu electrocatalysts with abundant distorted nanotwins (DNTs) for the first time. We start by producing Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles with numerous grain boundaries through pulsed laser ablation (PLA) in a liquid under oxidizing conditions. Subsequently, electroreduction of the Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles is employed to rearrange Cu atoms and form pure Cu nanoparticles containing a significant amount of DNTs (referred to as DNTs-Cu). The low atomic coordination number and strong tensile strain within the crystal lattice of DNTs-Cu appropriately enhance the interaction between copper and intermediates. Consequently, DNTs-Cu exhibits high catalytic activity and remarkable catalytic stability, surpassing even commercial Pt/C catalysts at current densities exceeding 100 mA cm\u003csup\u003e-2\u003c/sup\u003e, making it the best-performing HER catalyst among all copper-based materials.\u003c/p\u003e"},{"header":"Distorted nanotwins in Cu nanoparticles","content":"\u003cp\u003eThe synthesis of DNTs-Cu involved a two-step process, namely PLA plus electroreduction, as illustrated in \u003cstrong\u003eFig. 1a\u003c/strong\u003e. Firstly, the Cu target was ablated in water to yield out-of-order Cu atomic vapor by PLA, and then the Cu atomic vapor was oxidized instantaneously to form copper oxide nanoparticles. The broadened diffraction peaks in X-ray diffraction (XRD) pattern (\u003cstrong\u003eSupplementary Fig. 1a\u003c/strong\u003e) and the high-resolution transmission electron microscopy (HRTEM) images in \u003cstrong\u003eFig. 1b\u003c/strong\u003e and \u003cstrong\u003eSupplementary Fig. 2\u0026nbsp;\u003c/strong\u003efurther prove that the formed copper oxides are polycrystalline Cu\u003csub\u003e2\u003c/sub\u003eO (PC-Cu\u003csub\u003e2\u003c/sub\u003eO) nanoparticles containing many nanocrystalline grains with different orientations. The average particle size of PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles is 15.2 \u0026plusmn; 0.5 nm while the average grain size of nanocrystals is 3.1 \u0026plusmn; 0.2 nm (\u003cstrong\u003eSupplementary Fig. 1b)\u003c/strong\u003e. Secondly, PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles were electroreduced to pure Cu nanoparticles in the neutral electrolyte under -1.2 V vs reversible hydrogen electrode (RHE), as denoted as DNTs-Cu (-1.2 V). The XRD pattern (\u003cstrong\u003eSupplementary Fig. 1a\u003c/strong\u003e) and the auger electron spectroscopy (\u003cstrong\u003eSupplementary Fig. 1c\u003c/strong\u003e) demonstrate a complete transformation of Cu\u003csub\u003e2\u003c/sub\u003eO into Cu phase after the electroreduction treatment. Atomic resolution high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) images in\u003cstrong\u003e\u0026nbsp;Figs. 1c\u003c/strong\u003e and \u003cstrong\u003e1d\u003c/strong\u003e reveal the presence of a significant number of nanotwins in DNTs-Cu (-1.2 V). Additionally, lots of atomic steps are observed on the surface as marked by the hollow arrows in DNTs-Cu (-1.2 V) in \u003cstrong\u003eFig. 1d\u003c/strong\u003e, suggesting more low coordination Cu atoms on the surface of nanoparticles.\u003c/p\u003e\n\u003cp\u003eFurthermore, three additional electroreduction potentials (-1.4 V, -1.0 V and -0.8 V) were employed to reduce PC-Cu\u003csub\u003e2\u003c/sub\u003eO. The XRD patterns show that the formed DNTs-Cu (-0.8 V), DNTs-Cu (-1.0 V) and DNTs-Cu (-1.4 V) are also pure Cu nanoparticles, as depicted in \u003cstrong\u003eSupplementary Fig. 3\u003c/strong\u003e. The TEM images in \u003cstrong\u003eSupplementary Figs. 4 - 7\u003c/strong\u003e reveal that only a small number of nanotwins are found after electroreduction at -0.8 V, and the density of nanotwins gradually increases as decreasing the reduction potential from -0.8 V to -1.2 V, however, keeps relatively constant when the reduction potential further decreases from -1.2 V to -1.4 V. The evolution trend for the density of nanotwins is consistent with the broadening of XRD peaks in \u003cstrong\u003eSupplementary Fig. 3\u003c/strong\u003e. The local structure of Cu in DNTs-Cu was further investigated by\u003cem\u003e\u0026nbsp;in-situ\u003c/em\u003e X-ray absorption spectroscopy (XAS, \u003cstrong\u003eSupplementary Fig. 8\u003c/strong\u003e). \u003cstrong\u003eFig. 1e\u003c/strong\u003e shows the X-ray absorption near-edge structure spectroscopy (XANES) at Cu K-edge of DNTs-Cu, from which it is clearly revealed that PC-Cu\u003csub\u003e2\u003c/sub\u003eO is reduced to metallic Cu at the reduction voltages lower than -0.8 V according to the shift of the absorption edge from 8981.7 eV for Cu\u003csub\u003e2\u003c/sub\u003eO to 8980.1 eV for Cu as well as the change of the oscillation after absorption edge. After Fourier transformation, the radial distribution functions in \u003cstrong\u003eFig. 1f\u0026nbsp;\u003c/strong\u003edemonstrate that the Cu-Cu bond length in DNTs-Cu nanoparticles is significantly larger than 2.158\u0026nbsp;\u0026Aring;\u0026nbsp;of the reference\u0026nbsp;Cu foil, and\u0026nbsp;gradually\u0026nbsp;increase with the decrease of reduction potential to\u0026nbsp;2.185\u0026nbsp;\u0026Aring;\u0026nbsp;in DNTs-Cu (-0.8 V), 2.211\u0026nbsp;\u0026Aring;\u0026nbsp;in DNTs-Cu (-1.0 V), 2.255\u0026nbsp;\u0026Aring;\u0026nbsp;in DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V), respectively. Meanwhile, by least-squares curve fitting of the first shell Cu-Cu bond (\u003cstrong\u003eSupplementary Fig. 9\u003c/strong\u003e), the coordination numbers (CNs) of Cu in \u003cstrong\u003eFig. 1g\u003c/strong\u003e also decrease gradually with the decrease of reduction potential from 10.9 in DNTs-Cu (-0.8 V), 10.1 in DNTs-Cu (-1.0 V) to 9.5 in DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V). The increase of Cu-Cu bond length and the decrease of CNs provide evidences that the local structure of Cu could be effectively regulated by the designed two-step preparation.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Local structure analyses of DNTs-Cu","content":"\u003cp\u003eDNTs-Cu (-1.2 V) served as the representative sample, and its local structure was further analyzed using HRTEM technique, as depicting in \u003cstrong\u003eFig. 2\u003c/strong\u003e. From \u003cstrong\u003eFig. 2a\u003c/strong\u003e, we could observe that Cu nanograins are interconnected in the form of fourfold or fivefold twins, which indicate\u0026nbsp;the existence of tensile strain in\u0026nbsp;face-centered cubic metals\u003csup\u003e33, 34\u003c/sup\u003e. The FFT pattern crossing the twin boundary between Twin 1 and Twin 2 in \u003cstrong\u003eFig. 2b\u003c/strong\u003e confirms the distinct tensile strains within these nanotwins (similar results shown in \u003cstrong\u003eSupplementary Fig. 6\u003c/strong\u003e). For instance, in \u003cstrong\u003eFig. 2c\u003c/strong\u003e, the atom distance along [1\u0026nbsp;2] was measured to be 0.229 nm in line 1, which is different from the one along [112] of 0.242 nm in line 2. As compared with the standard atom distance of perfect Cu (0.222 nm along \u0026lt;112\u0026gt; direction), the increased atom distances in these two different [1\u0026nbsp;2] and [112] directions of Twin 1 indicate the existence of lattice tensile strain of 3.1% and 9.0%, respectively, resulting in an average lattice tensile strain approximately being 6%.\u0026nbsp;However, Twin 3 (\u003cstrong\u003eFig. 2a\u003c/strong\u003e) with a few numbers of atomic layers exhibits a totally different lattice strain state, in which the\u0026nbsp;intersection angles between the lattice planes (111) and (1\u0026nbsp;1)\u0026nbsp;change from 73.7\u0026deg;\u003csup\u003e\u0026nbsp;\u003c/sup\u003eto 77.1\u0026deg; (\u003cstrong\u003eFigs. 2d\u0026nbsp;\u003c/strong\u003eand\u003cstrong\u003e\u0026nbsp;2e\u003c/strong\u003e), both are larger than the one of perfect Cu structures with 70.5\u0026deg;. It is notable that, the closer distance to the core of fivefold twin, the greater the deviation of the angle between (111) and (1 1) plane, which indicates that Twin 3 suffers a larger tensile strain but the strain distribution is not uniform. Additionally, geometric phase analyses (GPA) of this sample in \u003cstrong\u003eFig. 2h\u003c/strong\u003e show that axial strain (ɛ\u003csub\u003exx\u003c/sub\u003e, ɛ\u003csub\u003eyy\u003c/sub\u003e) and shear strain (ɛ\u003csub\u003exy\u003c/sub\u003e) are distributed differently in various twin regions, which could reach a maximum value of ~10%. Furthermore,\u0026nbsp;the edge dislocations with low CN at the twin boundary and the grain interior are observed (\u003cstrong\u003eFigs. 2f\u003c/strong\u003e and \u003cstrong\u003e2\u003c/strong\u003e\u003cstrong\u003eg\u003c/strong\u003e), which accompanies the\u0026nbsp;electroreduction process\u0026nbsp;from Cu\u003csub\u003e2\u003c/sub\u003eO to Cu\u003csup\u003e35-37\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eAtomic resolution electron tomography (AET) was utilized to further obtain the three-dimensional (3D) atomic structures of\u0026nbsp;DNTs-Cu (-1.2 V)\u003csup\u003e38\u003c/sup\u003e.\u0026nbsp;3D volume of a small\u0026nbsp;DNTs-Cu\u0026nbsp;nanoparticle was computed by reconstructing a tomographic tilt series by an algorithm reported elsewhere\u003csup\u003e39, 40\u003c/sup\u003e; and the 3D atomic coordinates of individual atoms were traced to produce an experimental atomic model of DNTs-Cu nanoparticle (Methods, \u003cstrong\u003eSupplementary Figs. 10\u0026nbsp;\u003c/strong\u003eand\u003cstrong\u003e\u0026nbsp;11\u003c/strong\u003e). From the experimental 3D coordinate, we quantitatively analyzed the coordination number (CN), bond length and 3D tensile strain at atomic resolution. As shown in \u003cstrong\u003eFigs. 3a\u003c/strong\u003e and \u003cstrong\u003e3b\u003c/strong\u003e, the nanoparticle contains complicated structures including nanotwin and dislocation. The\u0026nbsp;intersection angle between the lattice planes (111) and (1\u0026nbsp;1) varies from 74.2\u0026deg;\u003csup\u003e\u0026nbsp;\u003c/sup\u003ein domain 1 to 69.2\u0026deg; in domain 2, revealing a significantly different lattice strain, which is consistent with previous two-dimensional structure analysis in \u003cstrong\u003eFig. 2\u003c/strong\u003e. The CN of the surface atoms show that there are numerous atoms with low coordination in\u0026nbsp;DNTs-Cu (-1.2 V), and the CNs of some atoms could even be reduced to 4 or 5 (\u003cstrong\u003eFig. 3c\u003c/strong\u003e), which may derive from the atomic step caused by rearrangement of Cu atom during electroreduction. Radial distribution function (RDF, \u003cstrong\u003eFig. 3d\u003c/strong\u003e) plots of all three nanotwins reveal that the overall Cu-Cu bond lengths become longer, particularly in domain 3, indicating a strong lattice expansion of DNTs-Cu, which agrees with the results of EXAFS and HRTEM analyses in \u003cstrong\u003eFig. 1f\u003c/strong\u003e and \u003cstrong\u003eFig. 2\u003c/strong\u003e. Furthermore, the 3D displacement field and full strain tensor analyses of the atomic slices in \u003cstrong\u003eFigs. 3f-3j\u0026nbsp;\u003c/strong\u003eand\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eSupplementary Fig. 12\u003c/strong\u003e show that the strong shear strain in Z direction (ɛ\u003csub\u003ezz\u003c/sub\u003e, ɛ\u003csub\u003exz\u003c/sub\u003e, ɛ\u003csub\u003eyz\u003c/sub\u003e) introduces significant tensile strain, and the maximum tensile strain reaches up to ~10% as shown in \u003cstrong\u003eFigs. 3f-3j\u0026nbsp;\u003c/strong\u003eand\u003cstrong\u003e\u0026nbsp;Fig. 2c\u003c/strong\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAccording to the DFT calculations in\u0026nbsp;\u003cstrong\u003eSupplementary Figs. 13 - 17,\u0026nbsp;\u003c/strong\u003ewith the increase of tensile strain and the reduction of coordination number,\u0026nbsp;the number of electrons shared between Cu atoms would decrease, leading to\u0026nbsp;an upshift of d-band center and a decrease of \u0026Delta;G\u003csub\u003eH*\u003c/sub\u003e. In particular, when the coordination number decreased to 5 while a 6% tensile strain was introduced, the\u0026nbsp;\u0026Delta;G\u003csub\u003eH*\u003c/sub\u003e of Cu(111)/(110) surface approaches an optimized value close to zero, indicating that fantastic HER catalytic performance. Therefore,\u0026nbsp;due to the ability to measure the strain and coordination number of each atom based on the 3D experimental model, the structural information of Cu atoms at the surface could be separated and studied in detail. As shown in\u0026nbsp;\u003cstrong\u003eFigs. 3e\u003c/strong\u003e and \u003cstrong\u003e3k\u003c/strong\u003e, numerous surface Cu atoms exhibit tensile strain and low coordination, and even part of surface atoms show high tensile strain (\u0026ge; 6%) and very low coordination number (\u0026le; 5), which are\u0026nbsp;recognized as active sites in DFT.\u0026nbsp;Moreover, electron holography experiment was carried out to visually map out the local electric field and charge density distribution in DNTs-Cu (-1.2 V). The charge distribution map in\u0026nbsp;\u003cstrong\u003eSupplementary Fig. 18\u0026nbsp;\u003c/strong\u003eclearly demonstrates that many electron-deficient regions segregate at the surface and twin boundaries of the DNTs-Cu nanoparticles, indicating that the low CN and strained Cu atoms at the surface of nanoparticles are with electron-deficient state and very likely to act as the highly active HER catalytic sites.\u003c/p\u003e"},{"header":"Excellent HER activity and durability of DNTs-Cu","content":"\u003cp\u003eThe HER properties of DNTs-Cu catalysts were evaluated in a standard three-electrode system\u0026nbsp;at room temperature, using RHE calibration without insulation resistance compensation (\u003cstrong\u003eSupplementary Figs. 19 - 22\u003c/strong\u003e). For comparison,\u0026nbsp;monocrystal Cu nanoparticles (5.95\u0026plusmn;0.2 nm in diameter, marked as MC-Cu in \u003cstrong\u003eSupplementary Fig. 23\u003c/strong\u003e) and Cu film (~50 nm in thickness in \u003cstrong\u003eSupplementary Fig. 24\u003c/strong\u003e) have also been prepared and tested.\u0026nbsp;As shown in \u003cstrong\u003eFigs. 4a\u003c/strong\u003e, \u003cstrong\u003e4b\u003c/strong\u003e and \u003cstrong\u003eSupplementary Fig. 25\u003c/strong\u003e, HER activities of DNTs-Cu, which are significantly better than that of MC-Cu and Cu film, gradually enhance with the decrease of electroreduction potential\u0026nbsp;from -0.8 V to -1.2 V. When the electroreduction potential was further reduced to -1.4 V, the HER performance of DNTs-Cu (-1.4 V) becomes quite similar with that of DNTs-Cu (-1.2 V) as displayed in \u003cstrong\u003eSupplementary Fig. 26\u003c/strong\u003e. For instance, at a current density of 10 mA cm\u003csup\u003e-2\u003c/sup\u003e, the overpotential\u0026nbsp;distinctly decreases from 632 mV for Cu foam, 589 mV for Cu film, 441 mV for MC-Cu, 287 mV for DNTs-Cu (-0.8 V), 170 mV for DNTs-Cu (-1.0 V) to 61 mV for DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V). Since the curve overlapping for DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V), the HER properties of DNTs-Cu (-1.4 V) were removed in \u003cstrong\u003eFig. 4\u003c/strong\u003e for clearer illustration. Compared with Pt/C, DNTs-Cu (-1.2 V) presents nearly comparable HER performance at the small current density of 10 mA cm\u003csup\u003e-2\u003c/sup\u003e (\u003cstrong\u003eFigs. 4a and 4b\u003c/strong\u003e). However, when the\u0026nbsp;current density increases to greater than 100 mA cm\u003csup\u003e-2\u003c/sup\u003e, the HER performance of DNTs-Cu (-1.2 V) significantly surpasses that of Pt/C\u0026nbsp;as shown in \u003cstrong\u003eFig. 4c\u003c/strong\u003e. For example,\u0026nbsp;at 500 mA cm\u003csup\u003e-2\u003c/sup\u003e, the overpotentials of DNTs-Cu (-1.2 V) is 301 mV, which is significantly lower than 425 mV for Pt/C, suggesting a greater potential for industrial applications of DNTs-Cu (-1.2 V)\u003csup\u003e41, 42\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eTo explore the intrinsic activity of catalysts, the exchange current densities (\u003cem\u003ej\u003csub\u003e0\u003c/sub\u003e\u003c/em\u003e) were calculated using the Tafel formula. As shown in \u003cstrong\u003eFig. 4d\u003c/strong\u003e, the\u0026nbsp;\u003cem\u003ej\u003csub\u003e0\u003c/sub\u003e\u003c/em\u003e of DNTs-Cu also enhances along with the decrease of electroreduction potential, and the highest\u0026nbsp;\u003cem\u003ej\u003csub\u003e0\u003c/sub\u003e\u003c/em\u003e of 1.1 \u0026times; 10\u003csup\u003e-3\u003c/sup\u003e A cm\u003csup\u003e-2\u003c/sup\u003e is found for DNTs-Cu (-1.2 V), which is twice as much as that of 5.5 \u0026times; 10\u003csup\u003e-4\u003c/sup\u003e A cm\u003csup\u003e-2\u003c/sup\u003e for Pt/C. Compared to the theoretical value, the high \u003cem\u003ej\u003csub\u003e0\u003c/sub\u003e\u003c/em\u003e of DNTs-Cu (-1.2 V) moves Cu from the bottom up to the top of volcano plots, achieving an intrinsic activity superior to that of Pt. Meanwhile,\u0026nbsp;the HER activity of DNTs-Cu (-1.2 V) has been also compared with other well-developed Cu-based catalysts. The comparison results in \u003cstrong\u003eFig. 4e\u003c/strong\u003e and \u003cstrong\u003eSupplementary Table 1\u003c/strong\u003e convince that DNTs-Cu (-1.2 V) exhibits much higher catalytic activity than all other Cu-based catalysts reported so far, even better than some noble metal-Cu alloys.\u003c/p\u003e\n\u003cp\u003eTo further validate the origin of the excellent HER activity of DNTs-Cu, DNTs-Cu (-1.2 V) was annealed under vacuum condition to remove DNTs. The annealed sample was denoted as annealed-DNTs-Cu (-1.2 V) as shown in \u003cstrong\u003eSupplementary Fig. 27\u003c/strong\u003e and its HER performance was investigated. After annealing, the XRD peaks of annealed-DNTs-Cu (-1.2 V) narrowed (\u003cstrong\u003eSupplementary Fig. 28\u003c/strong\u003e), indicating an enhancement in crystallinity. The SEM and TEM characterizations reveal that the nanoparticle size is basically unchanged, but the DNTs in annealed-DNTs-Cu (-1.2 V) have almost completely disappeared and the lattice has been restored to a perfect Cu lattice without any tensile distortion, as shown in \u003cstrong\u003eSupplementary Figs. 29\u0026nbsp;\u003c/strong\u003eand\u003cstrong\u003e\u0026nbsp;30.\u003c/strong\u003e The XAS results of annealed-DNTs-Cu (-1.2 V) in \u003cstrong\u003eSupplementary Fig. 31\u0026nbsp;\u003c/strong\u003edemonstrate that the Cu-Cu bond length shortens\u0026nbsp;to 2.161 \u0026Aring; and CN increases to 11.6, further confirming the elimination of tensile strain and crystal defects due to annealing. Meanwhile, the HER performance in \u003cstrong\u003eSupplementary Fig. 32\u003c/strong\u003e shows that the overpotential increases from 61 mV to 543 mV and the Tafel slope also raises from 33 mV/dec to 227 mV/dec for DNTs-Cu (-1.2 V) and annealed-DNTs-Cu (-1.2 V), respectively. This severe degradation in catalytic performance in turn demonstrates that the excellent HER performance in DNTs-Cu (-1.2 V)\u0026nbsp;originates from the synergistic effect of the low CN and strong tensile strain.\u003c/p\u003e\n\u003cp\u003eIn addition, the catalytic durability of DNTs-Cu (-1.2 V) is investigated and the results are shown in \u003cstrong\u003eFig. 4f\u003c/strong\u003e and \u003cstrong\u003e4g\u003c/strong\u003e.\u0026nbsp;After an accelerated durability test (ADT) of 5000 cycles, no obvious change of the polarization curve can be observed for DNTs-Cu (-1.2 V), however, a serious deterioration is detected for Pt/C, which makes the HER performance after ADT of Pt/C far inferior to that of DNTs-Cu (-1.2 V). Moreover, as illustrated in \u003cstrong\u003eFig. 4h\u003c/strong\u003e, after 125 h of continuous \u003cem\u003ei\u003c/em\u003e-\u003cem\u003et\u003c/em\u003e testing at a huge current density of 500 mA cm\u003csup\u003e-2\u003c/sup\u003e, the current density of DNTs-Cu (-1.2 V) merely decreases by ~2%, meanwhile the morphology and the local structure of DNTs-Cu remains unchanged in \u003cstrong\u003eSupplementary Figs. 33\u003c/strong\u003e-\u003cstrong\u003e35.\u003c/strong\u003e In contrast, the current density of commercial Pt/C drops by ~46% only after 14 h continuous measurement (the inset of \u003cstrong\u003eFig. 4h\u003c/strong\u003e).\u003c/p\u003e"},{"header":"Key role of grain boundaries in PC-Cu2O","content":"\u003cp\u003eThe phase transformation from Cu\u003csub\u003e2\u003c/sub\u003eO to Cu by electroreduction was widely used for carbon dioxide reduction reaction (CRR). Interestingly, no DNTs have been observed in electroreduction-derived Cu during CRR\u003csup\u003e43-46\u003c/sup\u003e. A comprehensive comparison between the CRR electroreduction process and our experiment suggests that the high density of grain boundaries in PC-Cu\u003csub\u003e2\u003c/sub\u003eO may be a critical factor in DNTs formation. For the PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles composed of ~3 nm Cu\u003csub\u003e2\u003c/sub\u003eO nanograins, the applied negative reduction potential would preferentially trigger the rapid transition from Cu\u003csub\u003e2\u003c/sub\u003eO lattice into\u0026thinsp;Cu lattice at\u0026nbsp;the\u0026nbsp;abundant\u0026nbsp;grain\u0026nbsp;boundary sites, because the Cu diffusion energy barrier of 0.22 - 0.31\u0026thinsp;eV at\u0026nbsp;the\u0026nbsp;grain boundaries is much smaller than 0.57 - 0.64\u0026thinsp;eV for O-vacancy assistant bulk Cu diffusion\u003csup\u003e35\u003c/sup\u003e. Meanwhile, considering that the transition from Cu\u003csub\u003e2\u003c/sub\u003eO into Cu has strictly crystal plane inheritance of Cu\u003csub\u003e2\u003c/sub\u003eO(110)/Cu(110) and Cu\u003csub\u003e2\u003c/sub\u003eO(100)/Cu(100)\u003csup\u003e35\u003c/sup\u003e, the rapid reduction of PC-Cu\u003csub\u003e2\u003c/sub\u003eO at grain boundaries simultaneously yields a large number of Cu nanocrystals with different orientations. As these crystals amalgamate, the mismatches at the interfaces necessitate substantial lattice matching adjustments in the epitaxially transformed Cu lattice, thereby inducing high tensile strain. With the increase of the electroreduction potential from -0.8 V to -1.2 V, the kinetics of the whole electroreduction processes are accelerated. This acceleration reduces the time available for lattice matching adjustments and prevents the dissipation of stress and strain, and as a result, more stress and strain are stored in DNTs-Cu (-1.2 V) (\u003cstrong\u003eSupplementary Figs. 4 - 7\u003c/strong\u003e)\u003csup\u003e33, 47\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eTo further investigate the influence of grain boundaries, PC-Cu\u003csub\u003e2\u003c/sub\u003eO was annealed to eliminate grain boundaries, resulting in the formation of monocrystalline Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles of comparable size (\u003cstrong\u003eSupplementary Fig. 36\u003c/strong\u003e). These monocrystal Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles were then subjected to electroreduction at -1.2 V under the same reduction conditions to produce Cu nanoparticles as shown in \u003cstrong\u003eSupplementary Fig. 37\u003c/strong\u003e. This formed sample was denoted as Annealed-PC-Cu (-1.2 V). Consistent with the reports for CRR, no obvious DNTs were identified in Annealed-PC-Cu (-1.2 V). The corresponding HER activity\u0026nbsp;shows that the overpotential at 10 mA cm\u003csup\u003e-2\u003c/sup\u003e and\u0026nbsp;Tafel slope of Annealed-PC-Cu (-1.2 V) were 390 mV and 176 mV/dec, respectively, which are comparable to 441 mV and 204 mV/dec for MC-Cu but are\u0026nbsp;significantly higher than 61 mV and 33 mV/dec for DNTs-Cu (-1.2 V).\u0026nbsp;Therefore, it can be concluded that the presence of numerous grain boundaries and extremely small grain sizes in PC-Cu\u003csub\u003e2\u003c/sub\u003eO are critical prerequisites for the formation of DNTs.\u0026nbsp;All these results suggest that during the rapid electroreduction process from Cu\u003csub\u003e2\u003c/sub\u003eO to Cu, the\u0026nbsp;abundant\u0026nbsp;grain boundaries of the initial PC-Cu\u003csub\u003e2\u003c/sub\u003eO trigger the simultaneous formation of multiple crystallographic orientation of Cu in each nanoparticle, which promotes the formation of multiple nano-twinned structures and locks up the localized lattice distortion strains with various crystal defects.\u0026nbsp;To demonstrate the general versatility of\u0026nbsp;electroreduction-driven local structure regulation, polycrystalline Ag\u003csub\u003e2\u003c/sub\u003eO nanoparticles with a large number of nanocrystalline grains were prepared and electroreduced under -1.2 V (\u003cstrong\u003eSupplementary Fig. 38\u003c/strong\u003e). As excepted, abundant distorted nanotwins could be clearly observed in pure Ag (\u003cstrong\u003eSupplementary Figs. 39 - 41\u003c/strong\u003e)\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eand result in a significant improvement of the HER activity of Ag (\u003cstrong\u003eSupplementary Fig. 42\u003c/strong\u003e).\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, a highly active and stable pure Cu catalyst was successfully prepared and its fantastic HER performance was investigated for the first time. Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles with abundant grain boundaries were firstly prepared by PLA and then were electroreduced to form DNTs-Cu. Systematic experiments and calculations demonstrated that a strong tensile strain was introduced in DNTs-Cu and the CN of Cu was significantly decreased, resulting in an enhancement of the adsorption capacity of Cu for catalytic intermediate H\u003csup\u003e*\u003c/sup\u003e. As anticipated, DNTs-Cu demonstrates remarkable HER catalytic performance in acid conditions, even better than commercial Pt/C under the high working current density. The approach of DNTs formation in metals via electroreduction as well as the principle of tuning ΔG\u003csub\u003eH*\u003c/sub\u003e by changing coordination number and tensile strain have been validated to be powerful strategies for activating HER catalysis of metals that are typically non-active.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e \u003cb\u003eReagents and Materials.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eCopper target (99.99%), copper foil (99.99%) and copper foam (99.99%) were purchased from Tianjin Incole Union Technology Co., Ltd. Potassium bicarbonate (KHCO\u003csub\u003e3\u003c/sub\u003e) was purchased from Aladdin (Shanghai). Commercial Pt/C (20 wt%) catalyst was purchased from Johnson Matthey. Nafion solution (5 vol%) was purchased from Dupont. All chemical reagents were used as received without further purification.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of PC-Cu\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eO nanoparticles.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles were prepared by pulsed laser ablation of Cu target in deionized water using a nanosecond pulsed Nd:YAG laser (Nimma-600, Beamtech) with the spot diameter about 2 mm at the pulse width of 7 ns, the wavelength of 1064 nm, the frequency of 15 Hz and the energy of 500 mJ. Before the laser ablation, the Cu target (20 mm in diameter and 5 mm in thickness) was polished and washed by diluted hydrochloric acid to remove the oxide layer. The target was placed in a 100 ml beaker containing deionized water with its upper surface 10 mm from the water surface, then ablated for 30 min to get the colloidal solution containing PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles. In the ablation process, the breaker was placed in ice bath. Then the colloidal solution was enriched by a high-speed centrifuge (19000 rpm, 20 min, 10 \u0026deg;C, SIGMA-3K30), and then vacuum freeze-dried (Biocool-FD-1-50) to obtain the PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles powder.\u003c/p\u003e \u003cp\u003e \u003cb\u003ePreparation of DNTs-Cu.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eTypically, 50 mg PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles was suspended in 5 ml isopropanol, 5ml deionized water and 5 \u0026micro;l Nafion solution (5 wt.%, Du Pont) to form a homogeneous ink assisted by ultrasound. Then the homogeneous ink was spread onto the surface of Cu foam by air brush and dried under room temperature. The electrochemical reduction of PC-Cu\u003csub\u003e2\u003c/sub\u003eO to prepare DNTs-Cu electrode was performed under atmospheric conditions in Ar-saturated 0.1 M KHCO\u003csub\u003e3\u003c/sub\u003e aqueous solution (pH 6.8) using a standard three-electrode electrolysis cell. A PC-Cu\u003csub\u003e2\u003c/sub\u003eO@Cu foam electrode was used as working electrode. The counter and reference electrodes were a graphite rod and a KCl-saturated Hg/Hg\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e electrode respectively. The electrochemical reduction was performed at the potential of -0.8 V, -1.0 V, -1.2V and \u0026minus;\u0026thinsp;1.4 V (\u003cem\u003evs.\u003c/em\u003e RHE) for 30 min to get DNTs-Cu (-0.8 V), DNTs-Cu (-1.0 V), DNTs-Cu (-1.2 V) and DNTs-Cu (-1.4 V) electrode, respectively. The DNTs-Cu electrodes were washed by deionized water under Ar protection and dried in vacuum drier.\u003c/p\u003e \u003cp\u003e \u003cb\u003ePreparation of MC-Cu and Cu film.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe MC-Cu was prepared by magnetron sputtering (LEICA EM SCD 500) under vacuum using Cu foam as substrate. The electric current of magnetron sputtering is 100 mA and sputtering time is 100 s. The Cu film electrode was prepared by thermal evaporation (oerlikon UNIVEX 250) under vacuum using Cu foam as substrate. The electric current of thermal evaporation is 140 A.\u003c/p\u003e \u003cp\u003e \u003cb\u003eAnnealing of DNTs-Cu (-1.2 V) and PC-Cu\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eO.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe annealing of DNTs-Cu (-1.2 V) was carried out in a tube furnace with Ar protection under 400 \u0026deg;C for 2h. The annealing of PC-Cu\u003csub\u003e2\u003c/sub\u003eO nanoparticles was carried out in a tube furnace with Ar protection under 400 \u0026deg;C for 5h.\u003c/p\u003e \u003cp\u003e \u003cb\u003eMaterials characterizations.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe TEM images were taken on a JOEL 2100F transmission electron microscope. The SEM images were taken on a Hitachi S-4800 scanning electron microscope. HAADF-STEM was performed using a JEOL ARM200F microscope with the STEM aberration corrector operated at 200 kV and spherical aberration correction TEM of ETEM (Thermofisher) with accelerated voltage of 300 kV. The convergent semiangle and collection angle for HAADF acquisition were 21.5 and 200 mrad, respectively. The aberration coefficient (C\u003csub\u003es\u003c/sub\u003e) used was equal to 1 \u0026micro;m. Geometric-phase analysis to obtain the strain information on the surface of DNTs-Cu (-1.2 V) was conducted with Digital Micrograph software. The X-ray diffraction with Cu Kα radiation as the radiation source through a Ni filter (Bruker D8 Advanced) was used to determine the crystalline structure of the catalysts. In situ XAS measurements were operated at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility (SSRF). All of XAFS data were recorded during one period of beam time. The acquired XAFS data were analyzed by Athena and Artemis software according to the standard procedures. The charge distribution map was performed using JEOL 2100F transmission electron microscope. Auger electron spectroscopy was measured by a THERMO SCIENTIFIC ESCALAB 250Xi.\u003c/p\u003e \u003cp\u003eTomographic tilt series with a tilt range of from \u0026minus;\u0026thinsp;76\u0026deg; to +\u0026thinsp;69\u0026deg; with the increment of 2 to 3\u003csup\u003eo\u003c/sup\u003e for a DNTs-Cu nanoparticle was acquired on an aberration-corrected microscope operated at 300 kV with a screen current of 20pA. Three sequential images were obtained with a dwell time of 2 \u0026micro;s in each tilt angle to minimize sample drift. After image denoising, background subtracting and alignment, 3D reconstruction was computed from the tilt series using an iterative algorithm\u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e. All the 3D atom coordinates were determined by identifying all the local maxima and locating the peak positions using polynomial fitting in the 3D reconstruction. Using the ideal fcc structure as the best-fit lattice\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e, we calculated the atomic displacement field based on the 3D coordinates of the individual atoms. A 3.4-\u0026Aring;-wide Gaussian kernel is convolved with the displacement field to reduce the noise. The 3D strain tensor is then calculated by differentiation of the displacement field.\u003c/p\u003e \u003cp\u003e \u003cb\u003eElectrochemical measurements.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe HER electrochemical measurements were performed in Ar-saturated 0.5 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e aqueous solution in a standard three-electrode electrolysis cell using prepared DNTs-Cu (Cu film, MC-Cu)@Cu foam electrode as the working electrode, a graphite rod as the counter electrode and a KCl-saturated Hg/Hg\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e electrode as the reference electrode. The commercial Pt/C@Cu foam electrode was also prepared as DNTs-Cu@Cu foam electrode and the final loading of catalysts on work electrode is 0.4 mg cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. The 0.5 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e solution was purged with Ar for about 60 min to exclude air. All the electrochemical measurements including cyclic voltammetry (CV), linear sweep voltammetry (LSV), current-time (i-t) and electrochemical impedance spectroscopy (EIS) were performed by the electrochemical workstation CHI660E. The Polarization curves under high potential were performed by the electrochemical workstation CHI1140C. Before each polarization curve test, 100 cycles of CVs were swept at a scan rate of 50 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to stabilize the catalysts. The LSVs were recorded by a scan rate of 5 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. All potentials were calibrated with respect to reversible hydrogen electrode (RHE) in the hydrogen-saturated electrolyte with Pt sheets as working electrode.\u003c/p\u003e \u003cp\u003e \u003cb\u003eComputational methods.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe DFT computation were performed using the Vienna ab initio simulation package (VASP) with the exchange correction function described by the generalized gradient approximation (GGA) within the Perdew-Burke-Ernzerhof (PBE). A plane wave basis was set to a cutoff energy of 450 eV. For structure relaxations, the convergence criteria were set to less than 0.03 eV/\u0026Aring; and 1\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e eV. The Cu surface was modelled with a 3\u0026times;3 unit cell and a four-layer slab, with the bottom two layers fixed. The vacuum layer was set to 15 \u0026Aring;. The Gibbs free energy of hydrogen adsorption is based on the computational hydrogen electrode (CHE) model from \u003cem\u003eΔG\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eΔE\u003c/em\u003e\u003csub\u003e\u003cem\u003eDFT\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;\u003cem\u003e+\u0026thinsp;ΔE\u003c/em\u003e\u003csub\u003e\u003cem\u003eZPE\u003c/em\u003e\u003c/sub\u003e \u003cem\u003e- TΔS\u003c/em\u003e, where \u003cem\u003eΔE\u003c/em\u003e\u003csub\u003e\u003cem\u003eDFT\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eΔE\u003c/em\u003e\u003csub\u003e\u003cem\u003eZPE\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eΔS\u003c/em\u003e correspond to the change of the calculated energy, zero point energy, and entropy at room temperature. According to the previous study, the free energy of hydrogen adsorption were calculated as \u003cem\u003eΔG\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eΔE\u003c/em\u003e\u003csub\u003e\u003cem\u003eDFT\u003c/em\u003e\u003c/sub\u003e + 0.24 eV. The differential charge density is used to reflect the electron transfer between Cu atoms, of which the positive value represents electron enrichment and the negative value represents electron loss. For metals, because the outer electrons are weakly bound by the nucleus, they often break away and become free electrons. Free electrons are shared between metal atoms, so the differential charge density between metal atoms is positive, while the internal is negative.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll relevant data are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe work at Fudan University was financially supported by National Key R\u0026amp;D Program of China (2020YFA0406204), National Natural Science Foundation of China (No. 52071083, 51922031, 12074016, 12274009 and 22172003), Science \u0026amp; Technology Commission of Shanghai Municipality (No. 20XD1420600), China Postdoctoral Science Foundation (No. BX2021066, 2021M700024), Zhuhai Fudan Innovation Institute, Beijing Natural Science Foundation (Z210016), the General Program of Science and Technology Development Project of Beijing Municipal Education Commission (KM202110005003) and the Research and Development Project from the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering (2022SX-TD001). The authors thank Renchao Che from Fudan university for charge distribution test. The authors thank the Electron Microscopy Laboratory at Peking University for the use of aberration-corrected electron microscopes and the High-performance Computing Platform of Peking University.\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\u003eAuthor Contributions\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eD. Sun and F. Fang conceived the experiments and supervised the project. Z.Li and Y. Wang designed and conducted the experiments. Z. Li, H. Liu. and F. Wang performed the experimental data analysis. Z. Li, Y. Lu and F.F. wrote the paper. Y. Wang, Y. Lu and M. Sui performed atomic-scale TEM measurements and analyzed the data. J. Zhou and Z. Xie performed atomic resolution electron tomography experiment and 3D structural analysis. X. Du M. Sui and D. Sun contributed the experimental platform. All authors discussed the results and commented on the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSupplementary information\u003c/strong\u003e is available in the online version of this paper.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eReprints and permissions information\u003c/strong\u003e is available at www.nature.com/reprints.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorrespondence and requests for materials\u003c/strong\u003e should be addressed to Jihan Zhou, Yue Lu, Dalin Sun and Fang Fang.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLin C et al (2021) In-situ reconstructed Ru atom array on α-MnO\u003csub\u003e2\u003c/sub\u003e with enhanced performance for acidic water oxidation. 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Nat Mater 14:1099\u0026ndash;1103\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-4161916/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4161916/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePrecious metals like Pt have been favored as catalysts due to their excellent catalytic activity for hydrogen evolution reaction (HER). However, the scarcity and high cost of precious metals have prompted researchers to explore alternative, non-precious metal catalysts. Cu is an attractive candidate for HER due to its plentiful reserves, affordability, and good electrical conductivity. However, Cu shows poor catalytic performance due to its weak binding with intermediates and is generally used as a current collector instead of a catalyst. Herein, the catalytic activity of pure Cu is greatly activated by electroreduction-driven local structure regulation, showing superior HER catalytic performance over commercial Pt/C catalysts at the working current densities greater than 100 mA cm\u003csup\u003e-2\u003c/sup\u003e in acid electrolyte. The activation process involved two steps. First, polycrystalline Cu\u003csub\u003e2\u003c/sub\u003eO were prepared by pulsed laser ablation, resulting in abundant grain boundaries within Cu\u003csub\u003e2\u003c/sub\u003eO particles. Next, the Cu\u003csub\u003e2\u003c/sub\u003eO particles were electroreduced to nano pure Cu, inducing the formation of distorted nanotwins and edge dislocations. These local structure regulations introduce strong lattice strain and decrease the Cu coordination number, which enhance the interaction between Cu and intermediates, leading to excellent catalytic activity and durability of pure Cu catalyst. The transformation of non-active nature into high catalytic activity, coupled with the intrinsic low cost, makes pure Cu a promising HER catalyst for large-scale industrial applications.\u003c/p\u003e","manuscriptTitle":"Electroreduction-Driven Distorted Nanotwins to Activate Pure Cu for Efficient Hydrogen Evolution","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-24 03:39:02","doi":"10.21203/rs.3.rs-4161916/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-materials","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"nmat","sideBox":"Learn more about [Nature Materials](http://www.nature.com/nmat/)","snPcode":"","submissionUrl":"","title":"Nature Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Research","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"3cd3bd05-e0a8-42dd-8bf6-30c45750e02c","owner":[],"postedDate":"April 24th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":31026818,"name":"Physical sciences/Materials science/Materials for energy and catalysis/Electrocatalysis"},{"id":31026819,"name":"Physical sciences/Materials science/Nanoscale materials/Nanoparticles"},{"id":31026820,"name":"Physical sciences/Chemistry/Catalysis/Electrocatalysis"}],"tags":[],"updatedAt":"2025-02-04T08:07:55+00:00","versionOfRecord":{"articleIdentity":"rs-4161916","link":"https://doi.org/10.1038/s41563-024-02098-2","journal":{"identity":"nature-materials","isVorOnly":false,"title":"Nature Materials"},"publishedOn":"2025-02-03 05:00:00","publishedOnDateReadable":"February 3rd, 2025"},"versionCreatedAt":"2024-04-24 03:39:02","video":"","vorDoi":"10.1038/s41563-024-02098-2","vorDoiUrl":"https://doi.org/10.1038/s41563-024-02098-2","workflowStages":[]},"version":"v1","identity":"rs-4161916","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4161916","identity":"rs-4161916","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}