Concave surface-enriched reactant and enhanced mass transfer for electrocatalytic ethylene production from low-concentrated acetylene

Concave surface-enriched reactant and enhanced mass transfer for electrocatalytic ethylene production from low-concentrated acetylene | 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 Concave surface-enriched reactant and enhanced mass transfer for electrocatalytic ethylene production from low-concentrated acetylene Bin Zhang, Li Li, Fanpeng Chen, Chuanqi Cheng, Yifu Yu, Bo-Hang Zhao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4215383/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 13 Jul, 2024 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Electrocatalytic semihydrogenation of acetylene (C 2 H 2 ) provides a facile and petroleum-independent strategy for ethylene (C 2 H 4 ) production. However, the reliance on the preseparation and concentration of raw coal-derived C 2 H 2 hinders its economic potential. Here, density functional theory calculations demonstrate that a concave surface is beneficial for enriching C 2 H 2 and optimizing its mass transfer kinetics, thus leading to a high partial pressure of C 2 H 2 around active sites, which is suitable for the direct conversion of raw coal-derived C 2 H 2 . Then, a porous concave carbon-supported Cu nanoparticle (Cu-PCC) electrode was designed to enrich the C 2 H 2 gas around the Cu sites. As a result, the as-prepared electrode enables a 91.7% C 2 H 4 Faradaic efficiency and a 56.31% C 2 H 2 single-pass conversion under a simulated raw coal-derived C 2 H 2 atmosphere (~ 15%) at a partial current density of 0.42 A cm − 2 , greatly outperforming its counterpart without concave surface supports. The strengthened intermolecular π conjugation caused by the increased C 2 H 2 coverage is revealed to result in the delocalization of π electrons in C 2 H 2 , consequently promoting C 2 H 2 activation, suppressing HER competition, and enhancing C 2 H 4 selectivity. Physical sciences/Chemistry/Electrochemistry/Electrocatalysis Physical sciences/Chemistry/Green chemistry/Sustainability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The production of the essential chemical ethylene (C 2 H 4 ) is highly dependent on high-temperature naphtha cracking, which relies on petroleum resources with excess carbon emissions. 1,2 Hence, developing a petroleum-independent and mild strategy for C 2 H 4 production is highly desirable for a low-carbon economy. 3–8 Recently, the electrocatalytic semihydrogenation of coal-derived acetylene (C 2 H 2 ) to ethylene (ESAE) strategy has been developed. 7,8 Inhibiting the competing hydrogen evolution reaction (HER) at an industrial current density (≥ 200 mA cm − 2 ) is pivotal for the economic potential of the ESAE strategy. At present, both the C 2 H 4 Faradaic efficiency (FE) and the optimal current density are extremely low for low-concentration C 2 H 2 hydrogenation (e.g., ˂50% FE at 60 mA cm − 2 for ~ 1% C 2 H 2 impurity hydrogenation in C 2 H 4 ), which is far from the target of practical C 2 H 4 production. 7 Additionally, the cost of separating and concentrating C 2 H 2 feed gas accounts for a large proportion of the total C 2 H 4 production cost. 8 Consequently, the cost of C 2 H 4 production would further decrease if the raw tail gas (~ 15% C 2 H 2 ) from the arc-plasma process of coal could be directly used as feedstock for the ESAE process. 8–13 However, the HER dominates the whole process as the C 2 H 2 concentration decreases (Fig. 1 a). Therefore, further development of highly efficient and selective catalysts for converting raw coal-derived C 2 H 2 into C 2 H 4 with high selectivity and conversion rates is urgently needed. Generally, for a gas-involved reaction, enriching its local concentration and boosting the mass transfer toward active sites are important for enhancing the reactant’s partial pressure to improve the activity and selectivity. 14–17 Copper (Cu) nanoparticles have been proven to be an appropriate choice for suppressing the competing HER under high C 2 H 2 partial pressure. 18–21 Thus, the critical issue for the selective conversion of raw coal-derived C 2 H 2 lies in enriching the concentration and guaranteeing the facile mass transfer of C 2 H 2 around the surface of the Cu nanoparticles. Structures with high curvatures always lead to a high local electric field, which can gather reactants around the catalyst surface and increase its concentration. 22–26 For example, Liu et al . demonstrated that Cu nanoneedles could increase the adsorption of the *CO intermediate and, in turn, accelerate C–C coupling during the electrocatalytic CO 2 reduction process 23 . In addition to the tips, the concave surface also has a high curvature. 27–29 Moreover, carbon-based supports with porous structures could effectively boost gas capture and transport, benefitting mass transfer. 30–32 In this regard, Cu nanoparticles loaded on porous carbon supports with abundant nanosized concave surfaces (denoted as Cu-PCC) are expected to be efficient at increasing the concentration and increasing the mass transfer of C 2 H 2 around Cu sites through the unique concave support, consequently suppressing the HER under low-concentration raw coal-derived C 2 H 2 (Fig. 1 b). However, the synthesis and exploration of porous concave carbon-supported Cu nanoparticle electrodes for electrocatalytic C 2 H 4 production are lacking. Herein, a preliminary density functional theory (DFT) calculation was first conducted to show that a concave surface is beneficial for the enrichment and facile mass transfer of C 2 H 2 , increasing its partial pressure around the active sites. Then, we designed a facile self-template method to synthesize Cu-PCC, which was found to be an outstanding electrocatalyst for the ESAE process, using simulated raw coal-derived C 2 H 2 as feedstocks. Cu-PCC delivered a C 2 H 4 FE of 91.70% and a single-pass C 2 H 2 conversion of 56.31% at a potential of − 1.2 V versus a reversible hydrogen electrode (vs. RHE) at a partial current density of 0.42 A cm − 2 , greatly outperforming the Cu nanoparticles supported on carbon without a concave surface counterpart. Moreover, C 2 H 2 temperature-programmed desorption (C 2 H 2 -TPD) and in situ spectroscopic characterization experiments revealed that the polarization field induced by the concave surface over Cu-PCC increased C 2 H 2 coverage and strengthened the intermolecular π -conjugation of C 2 H 2 , thus leading to the delocalization of the π electrons of C 2 H 2 to promote the activation of C 2 H 2 and enhance the C 2 H 4 selectivity of the ESAE with raw coal-derived C 2 H 2 . Results The design and synthesis of electrocatalyst We first conducted DFT calculations to evaluate the local field induced by the concave surface. As shown in Fig. 2 a, the electrons are enriched at the concave carbon surfaces to build a polarization field, which could enhance the conjugation between C 2 H 2 and the negative center (Fig. 2 b and Supplementary Fig. 1), thus leading to the downshifting of the bonding orbital and benefiting the enrichment of C 2 H 2 (Fig. 2 c). 21,29,33 Once the low-concentration C 2 H 2 accumulated on the concave carbon surfaces, facile migration to the Cu sites was still a prerequisite for the following reaction. In that case, simulations of the migration pathway of the C 2 H 2 molecule in solution over the Cu-C and Cu-PCC interfaces were conducted (Supplementary Figs. 2–3). For gas-involved reactions, there will be a few layers of water clusters (WC) due to the hydrogen bonding network around the gas‒solid-liquid three-phase interface and the gap between the WC and solid surface (labeled d in Fig. 2 d) provides a diffusion channel for gaseous reactants. As shown in Fig. 2 d, the diffusion channel for Cu-PCC is larger than that for Cu-C, thus leading to a straight-line migration pathway rather than a distorted pattern over the counterpart. The associated migration energy barriers were calculated, as shown in Fig. 2 e. The maximum migration energy for C 2 H 2 diffusion over Cu-PCC is 0.41 eV, which is much lower than that of Cu−C (1.23 eV), indicating that the mass transfer of C 2 H 2 is significantly greater over the concave surface. These theoretical results indicate that a carbon support with concave surfaces could efficiently gather low-concentration raw coal-derived C 2 H 2 feedstocks and increase the mass transfer kinetics for subsequent hydrogenation over Cu sites. Generally, the collapse and reconstruction of a surface increases the roughness and results in many nanosized concave surfaces. 34,35 Thus, a sequential self-template transformation method based on the Kirkendall effect was proposed for the synthesis of Cu-PCC (Fig. 3 a). 36,37 Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the successful preparation of Cu-based metal-organic framework precursors (Cu-MOF) with planar surfaces and octahedral-like morphologies (Supplementary Fig. 4). After the reaction of Cu-MOF precursors with tannic acid (TA), the octahedron-like shapes can be maintained, and the surface collapses inward (denoted as Cu-TA, Supplementary Fig. 5). After the annealing of Cu-TA under an H 2 atmosphere, the wall of the Cu-TA complex was converted into porous carbon with abundant nanosized concave surfaces, as confirmed by scanning transmission electron microscopy (STEM), SEM, and TEM images (Figs. 3 b, c and Supplementary Fig. 6). 38 However, Cu-C directly calcinated from Cu-MOF precursors without the collapse process exhibited a planar carbon surface (Figs. 3 d, e and Supplementary Fig. 7). Moreover, the atomic force microscopy (AFM) images also demonstrated the rougher surface of Cu-PCC caused by these concave surfaces compared to that of Cu-C (Fig. 3 f). In addition, X-ray diffraction (XRD) patterns, Fourier transform infrared (FTIR) spectra, and Raman spectra were obtained to monitor the sequential conversion process from Cu-MOF precursors to Cu-TA and eventually to Cu-PCC (Supplementary Fig. 8). The Raman, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) results show that there are no other differences between Cu-PCC and Cu-C, other than the nanosized concave surfaces over the PCC supports (Supplementary Figs. 9–11). Note that the negative shift in the binding energies of C-O and C = O over Cu-PCC compared to that over Cu-C verifies the existence of a polarization field (Fig. 3 g). 39–41 Furthermore, C 2 H 2 -TPD was employed to evaluate the C 2 H 2 gas enrichment ability of Cu-PCC. 42 The greater C 2 H 2 adsorption on Cu-PCC than on its Cu-C counterpart, along with the ever-increasing desorption temperature under similar specific surface areas (Fig. 3 h and Supplementary Fig. 12), indicated that the enriched C 2 H 2 and optimized mass transfer were the main reasons for the enhanced interactions between the C 2 H 2 feedstocks and Cu-PCC. ESAE reaction analysis and performance evaluation The ESAE process was evaluated in a three-electrode flow cell with a gas diffusion layer under potentiostatic conditions using simulated raw coal-derived C 2 H 2 (~ 15%) as the feeding gas. First, online differential electrochemical mass spectrometry (DEMS) was conducted under linear sweep voltammetry (LSV) mode to explore and analyze the ESAE process (Fig. 4a). In addition to Cu-PCC possessing a more positive onset potential for C 2 H 2 hydrogenation (− 0.06 V vs. RHE) than Cu-C (− 0.1 V vs. RHE), Cu-PCC has a much more negative HER onset potential, endowing Cu-PCC with a better ability to activate C 2 H 2 and suppress the HER (Figs. 4b, c and Supplementary Figs. 13–14). Moreover, the signal intensity of C 2 H 4 over Cu-C displays a nearly volcanic shape, and the response of H 2 acutely increases under potentials more negative than − 0.6 V vs. RHE. However, the C 2 H 4 signal always dominated the whole product until the end of the LSV over Cu-PCC. In other words, the production gap between C 2 H 4 and the H 2 byproduct becomes larger with decreasing potential over Cu-PCC, while it shows an inverse trend over Cu-C, further verifying the superiority of Cu-PCC in the ESAE process. In addition, the same electron transfer number of C 2 H 2 to C 2 H 4 and H 2 O to H 2 is likely the reason for the similar LSV curves of the two catalysts. Then, we performed the DEMS test under square wave potentials. For Cu-PCC, H 2 emerges under a much more negative potential than does its Cu-C counterpart. In addition, unlike the almost unchanged or even decreased C 2 H 4 signal observed for Cu-C, the C 2 H 4 signal increases with decreasing potential, indicating better C 2 H 4 selectivity in Cu-PCC under a raw coal-derived C 2 H 2 atmosphere (Figs. 4d, e). The quantification of the ESAE process showed that the FE of C 2 H 4 over Cu-PCC exceeded ~ 90%, and the C 2 H 6 byproduct was almost undetectable throughout the whole range (Fig. 5 a). However, the FE of C 2 H 4 decreased rapidly, with more H 2 produced at more negative potentials than − 0.8 V vs. RHE over Cu-C (Fig. 5 b). Furthermore, the obtained C 2 H 4 production rate of Cu-PCC at a potential of − 1.2 V vs. RHE was 3.42 mol g cat −1 h − 1 with a partial current density and C 2 H 2 conversion of 0.42 A cm − 2 and 56.31%, respectively, greatly surpassing those of its Cu-C counterpart (2.00 mol g cat −1 h − 1 , 0.26 A cm − 2 and 33.21% C 2 H 2 conversion) (Figs. 5 a, b). The superiority of the C 2 H 4 production rates of Cu-PCC became more obvious after normalization by the electrochemical surface area (ECSA) or Cu loading capacity (Fig. 5 c, and Supplementary Figs. 15–17). In addition, considering the demand for industrial production, stability evaluation experiments at various concentrations and step potentials for the hydrogenation of C 2 H 2 were performed. Accordingly, the 95% confidence intervals of FEs were calculated to evaluate the selectivity stability, as shown in Fig. 5 d. The narrower confidence intervals of the C 2 H 4 and H 2 FEs over Cu-PCC than Cu-C demonstrate that the fitted lines of FEs under different concentrations of Cu-PCC are more precise, 43 which means that the influence of concentration on FEs is less significant over Cu-PCC, 44 indicating its better stability. In addition, the FE and selectivity of C 2 H 4 remain unchanged at different potentials over Cu-PCC, which is superior to its counterpart (Fig. 5 e). These results indicate that the proposed Cu-PCC exhibits potential- and concentration-independent ESAE activity, which is suitable for practical application. Note that both the FE of C 2 H 4 and the C 2 H 2 conversion over Cu-PCC remained unchanged within the error range during the 12 h continuous test, suggesting its robust durability (Fig. 5 f and Supplementary Fig. 18). Mechanistic exploration of the high selectivity for ethylene To elucidate the reason for the increase in C 2 H 4 FE and selectivity over Cu-PCC under a raw coal-derived C 2 H 2 atmosphere, in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and Raman spectroscopies were used to evaluate the status and coverage of C 2 H 2 with the catalytic surface (Supplementary Figs. 19–20). Generally, the peak frequency of the IR or Raman characteristic peak is determined by the strength of the corresponding bond. 45–48 For C 2 H 2 , the enhanced π conjugation led to the redistribution of bonding electrons, and the corresponding π bond was weakened due to the delocalization of electrons, consequently leading to a negative shift in the peak frequency (redshift). 49 As shown in Figs. 6 a, b, both ν (C-H) (~ 3200 cm − 1 ) and ν (C ≡ C) (~ 1620 cm − 1 ) of C 2 H 2 over Cu-PCC shift to lower frequencies than do their Cu-C counterparts at each potential (Supplementary Figs. 21, 22), 7,8,50,51 indicating that the triple bond of C 2 H 2 becomes unstable over Cu-PCC due to the delocalization of π electrons; thus, the C 2 H 2 molecule is easier to activate. Moreover, the redshift of the peak attributed to adsorbed C 2 H 2 in the Raman spectrum from 1700 cm − 1 over Cu-C to 1685 cm − 1 over Cu-PCC also confirmed the attenuation of the π bonds of C 2 H 2 , further demonstrating that support with concave surfaces is beneficial for C 2 H 2 activation (Figs. 6 c, d). 20,21 In addition, considering that the integrals of the IR bands are related to the coverage of the respective adsorbate on the surface, the area ratio between ν (C ≡ C) and δ (H-O-H) was viewed as the descriptor of the relative coverage of C 2 H 2 over the catalyst surface. The plot of ν (C ≡ C)/ δ (H-O-H) over Cu-C exhibited a volcano-like profile, which began to decrease at potentials more negative than − 0.2 V vs. RHE, indicating that H 2 O adsorption improved with the negative shift potential and accounted for the strong HER competition. Conversely, the plot of ν (C ≡ C)/ δ (H-O-H) over Cu-PCC presented a nearly monotonically increasing trend with negatively shifted potentials (Fig. 6 e), demonstrating the higher C 2 H 2 coverage of Cu-PCC under the applied potential range and accounting for the enhanced intermolecular π conjugation and the delocalization of π electrons from C 2 H 2 . 52 Finally, we also conducted DFT calculations to evaluate the C 2 H 2 hydrogenation energy barrier under high and low coverage to verify our experimental results. As shown in Fig. 6 f, the hydrogenation barriers under high C 2 H 2 coverage are lower than those under low coverage (Supplementary Figs. 23–27), indicating easier activation of C 2 H 2 and better hydrogenation kinetics over Cu-PCC. Accordingly, the in-depth origins for the enhanced C 2 H 4 selectivity obtained using low-concentration raw coal-derived C 2 H 2 over Cu-PCC are summarized in Fig. 6 g. The C 2 H 2 feedstocks could be enriched by the nanosized concave carbon surfaces and then effectively transferred to the Cu sites, consequently resulting in high C 2 H 2 partial pressure and coverage. Then, the electron delocalization effect due to the increased C 2 H 2 coverage promoted C 2 H 2 activation, thus leading to satisfactory C 2 H 4 selectivity and FE over Cu-PCC. Discussion In summary, Cu nanoparticles loaded on carbon supports with abundant nanosized concave surfaces were designed to enhance C 2 H 2 adsorption for direct utilization of raw coal-derived C 2 H 2 . Cu-PCC delivered a C 2 H 4 FE of 91.7% and a single-pass C 2 H 2 conversion of 56.31% under a potential of − 1.2 V vs. RHE at a partial current density of 0.42 A cm − 2 , greatly outperforming its counterpart without the concave surface. Notably, the nanosized concave surfaces were significantly enriched in C 2 H 2 gas and had lower mass transfer kinetics, resulting in higher C 2 H 2 coverage. Moreover, the delocalization of π electrons in C 2 H 2 due to the strengthened intermolecular π conjugation caused by the increased C 2 H 2 coverage promoted the activation of C 2 H 2 , thus endowing Cu-PCC with robust HER suppression ability and better C 2 H 4 selectivity. Our work may not only demonstrate an efficient and selective catalyst for nonpetroleum C 2 H 4 electrosynthesis but also open a facile way to access low-concentration gaseous reactants for various catalytic applications. Methods Synthesis of Cu-MOF precursors. According to previous literature 37 , the Cu-MOF precursors were prepared by a PVP-assisted strategy as follows. First, 1.46 g of Cu(NO 3 ) 2 ·3H 2 O and 0.7 g of H 3 BTC were dissolved in 20 mL of DMF to form solution A and solution B, respectively. Subsequently, 0.5 g PVP was added to solution A and stirred for 5 min to obtain a homogenous solution. Then, solution B was mixed with solution A and stirred for an additional 10 min. Afterward, the mixture was transferred to a 100 mL Teflon-lined stainless-steel autoclave and maintained at 80°C for 24 h. Finally, the blue precipitates were harvested by centrifugation, washed with DIW and ethanol several times, and dried in a vacuum oven overnight to produce the Cu-MOF precursors. Synthesis of Cu-TA. The as-prepared Cu-MOF precursors (100 mg) and tannic acid (TA) (50 mg) were first dispersed into 50 mL of DIW to form two solutions. The two solutions were subsequently mixed at room temperature and stirred for 30 min. Afterward, the mixture was put into an oil bath at 50°C and refluxed under continuous magnetic stirring (stirring speed: 700 rpm) for 7 h. The precipitate was then washed with DIW and absolute ethanol at least three times to remove the residual TA and dried at 70°C in a vacuum oven overnight. Synthesis of Cu-PCC and Cu-C. To obtain Cu-PCC and Cu-C, the as-prepared Cu-TA and Cu-MOF precursors were annealed at 400°C for 2 h at a heating rate of 5°C min − 1 under a 3% H 2 /Ar atmosphere. The mixture was then naturally cooled to room temperature. General characterizations. Quasi- in situ powder X-ray diffraction (XRD) was performed on a Bruker D8 Focus Diffraction System (Germany) using a Cu K α radiation source (λ = 0.154178 nm). Scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) were conducted with an FEI Apreo S LoVac microscope (10 kV). Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images were obtained with a JEOL-2100F system equipped with an EDAX Genesis XM2. X-ray photoelectron spectroscopy (XPS) was conducted with a PHI-1600 X-ray photoelectron spectrometer equipped with Al K α radiation. All the peaks were calibrated with the Ti 2p spectrum since C 1s is a key parameter in our research. The Raman spectra were obtained with a Renishaw inVia reflex Raman microscope under excitation with a 514 nm laser at a power of 20 mW. Fourier transform infrared spectroscopy (FTIR) was performed on a Nicolet IS50 instrument. The Brunauer–Emmett–Teller (BET) surface area was measured by N 2 adsorption using a Micromeritics ASAP 2460. Inductively coupled plasma‒optical emission spectrometry (ICP‒OES) was conducted with an Agilent 5110 instrument (OES). Atomic Force Microscope (AFM) was carried out on a Bruker Dimension Icon. Electrochemical measurements in the flow cell. Electrochemical measurements were carried out in a typical flow cell consisting of a GDL as the working electrode, Pt foil as the counter electrode, and Hg/HgO as the reference electrode using a CS150H electrochemical workstation. The cathode cell and anode cell were separated by a Nafion 117 proton exchange membrane. The cathode and anode electrolytes were both composed of 1.0 M KOH solution, and a peristaltic pump was used to circulate the liquid phase. The gas flow rate was controlled by a mass flowmeter. Before the performance tests, the working electrode was fixed at the interface between the gas flow block and the cathodic electrolyte block by conductive copper tape. First, the electrochemical semihydrogenation of acetylene was conducted at different applied potentials for 10–20 min to achieve relatively stable and reliable performance parameters before quantitative analysis. The gas at the flow cell outlet was directly introduced into the gas chromatography system for analysis of the products. All the LSV curves were iR compensated with a compensation level of 70%. For the Tafel slopes, the LSV curves were replotted by using the logarithms of the current density as the x-axis and the potential as the y-axis. The obtained slopes of the linear part of the replotted figure were the Tafel slopes. Quantitative analysis of the C 2 H 2 conversion, evolution rate, and FE of the obtained products. The products were subjected to a GC-2010 gas chromatograph equipped with an activated carbon-packed column (with He as the carrier gas) and a barrier discharge ionization detector. The C 2 H 2 conversion and evolution rate of the different products were calculated using equations (1) and (2), and the FEs of the different products were calculated using Eq. (3). All the experiments were repeated three times. $$\text{Conversion }\left(\text{%}\right)\text{ = }\frac{\text{the peak area of B-peak area of A}}{\text{the peak area of B}}\text{ ×100% (1) }$$ $$\text{Evolution Rate (}\text{mmol}\text{/mg/h)=}\frac{\text{the peak area of X ×}\text{C}}{\text{the peak area of standard }\text{gas×}\text{m}\text{ }}\text{ × }\text{S }\text{ (2)}$$ $${\text{FE}}_{\text{X}}\left(\text{%}\right)\text{=}\frac{\text{a × }{\text{n}}_{\text{X}}\text{ ×}\text{F}}{\text{Q}} \text{(3)}$$ X: The different products, including H 2 , C 2 H 4 , and C 2 H 6 . C: The concentration of X in standard gas. m: The mass of catalysts over the electrode. n: The moles of different products, including H 2 , C 2 H 4 , and C 2 H 6 . A : Area of the C 2 H 2 outlet; B: area of the C 2 H 2 inlet. S: The gas flow rate. a: The electron transfer number. F: Faraday constant. Q: The total Coulomb number of the ESAE process. Electrochemical operando online DEMS analysis. Operando online DEMS analysis was conducted with a QAS 100 instrument provided by Linglu Instruments (Shanghai) Co., Ltd. Because the products in the proposed ESAE process were all in the gas phase, operando experiments were conducted to monitor the distribution of the products during the on-stream reaction, clarifying the selectivity issues more directly and clearly. The flow cell used in the performance evaluation and the DEMS were coupled to ensure that the gas at the flow cell outlet was directly injected into the negatively pressured gas circuit system of the DEMS through a quartz capillary that was inserted into the outlet of the flow cell. The LSV test and rectangular wave potentials were applied from − 0.6 to − 1.2 V vs. RHE with a constant interval of 400 s using a CS150H electrochemical workstation. During the experiment, the flow rates of C 2 H 2 gas and the electrolyte were set the same as those used for the performance evaluation. Electrochemical in situ ATR-FTIR measurements. In situ ATR-FTIR was performed on a Nicolet 6700 FTIR spectrometer equipped with an MCTA detector with silicon as the prismatic window and an ECIR-II cell by Linglu Instruments. First, Cu-PCC was carefully dropped on the surface of the gold film, which was chemically deposited on the surface of the silicon prismatic material before each experiment. Then, the deposited silicon prismatic material served as the working electrode. Pt foil and Hg/HgO with an internal reference electrolyte of 1.0 M KOH were used as the counter and reference electrodes, respectively. A 1 M KOH solution was used as the electrolyte. The electrolyte was presaturated with pure C 2 H 2 gas, and the gas was continuously bubbled through during the whole measurement. The spectrum was recorded every 30 s under an applied potential ranging from 0.2 to − 1.0 V vs. RHE. Electrochemical in situ Raman measurements. In situ electrochemical Raman spectra were recorded via an electrochemical workstation on a Renishaw inVia reflex Raman microscope under 532 nm laser excitation under controlled potentials. We used a homemade Teflon electrolytic cell equipped with a piece of round quartz glass for the incidence of lasers and protection of the tested samples1. Before the experiments, the electrolyte was pretreated with pure C 2 H 2 gas to obtain C 2 H 2 -saturated KOH. The working electrode was parallel to the quartz glass to maintain the plane of the sample perpendicular to the incident laser. The Pt wire was rolled to a circle around the working electrode to serve as the counter electrode. The reference electrode was Hg/HgO with an internal reference electrolyte of 1.0 M KOH. The spectrum was recorded under applied potentials ranging from 0.2 to − 1.0 V vs. RHE. Computational details. All the DFT calculations were performed using the Vienna ab initio simulation package (VASP). 53 The projector augmented wave (PAW) pseudopotential with the PBE generalized gradient approximation (GGA) exchange-correlation function was utilized in computations . 54,55 The cutoff energy of the plane wave basis set was 500 eV, and a Monkhorst-Pack mesh of 3×3×1 was used in K-sampling for the adsorption energy calculations and other nonself-consistent calculations. The long-range dispersion interaction was described by the DFT-D3 method. The electrolyte was incorporated implicitly with the Poisson-Boltzmann model implemented in VASPsol 56 . The relative permittivity of the media was chosen to be ϵ r = 78.4, corresponding to that of water. All atoms were fully relaxed with an energy convergence tolerance of 10 − 5 eV per atom, and the final force on each atom was < 0.05 eV Å −1 . The transition state (TS) searches were performed using the Dimer method in the VTST package. The final force on each atom was < 0.1 eV Å −1 . The TS search is conducted by using the climbing-image nudged elastic band (CI-NEB) method to generate initial guess geometries, followed by the dimer method to converge to the saddle points. The adsorption energy of the reaction intermediates can be computed using Eqs. (4)-(5): ∆ E = E *ads - ( E * + E ads ) (4) ∆ G = ∆ E + ∆ E ZPE - T ∆ S (5) where ∆ E ZPE is the zero-point energy change and ∆ S is the entropy change. In this work, the values of ∆ E ZPE and ∆ S were obtained via vibration frequency calculations. Declarations Data availability The source data underlying Figs. 1–6 are provided as a Source Data file. The data that support other plots within this paper are available from the corresponding author upon reasonable request. Acknowledgements We acknowledge the National Natural Science Foundation of China (Nos. 22271213 and 22209120). Author Contributions B. Zhang conceived the idea and directed the project. L. Li, B.-H. Zhao, and B. Zhang designed the experiments. L. Li. and F. P. Chen carried out the experiments and characterization. Y. F. Yu assisted in some experiments. C. Q. Cheng performed the DFT calculations. L. Li and B.-H. Zhao wrote the paper. B. Zhang revised the paper. All the authors discussed the results and commented on the paper. Competing Financial Interests The authors declare no competing interests. References Gomez, E., Yan, B., Kattel, S. & Chen, J. G. Carbon dioxide reduction in tandem with light-alkane dehydrogenation. Nat. Rev. Chem. 3 , 638−649, (2019). Bodke, A. S., Olschki, D. A., Schmidt, L. D. & Ranzi, E. High selectivities to ethylene by partial oxidation of ethane. Science 285 , 5428, (1999). Gao, Y. F. et al. Recent advances in intensified ethylene production—a review. ACS Catal. 9 , 8592−8621, (2019). Albani, D. et al. Semihydrogenation of acetylene on indium oxide: proposed single-ensemble catalysis. Angew. Chem. Int. Ed. 56 , 10755−10760, (2017). Jiao, X. C. et al. 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Supplementary Files LLXZBHNat.Commun.SI.docx SUPPLEMENTARY INFO Cite Share Download PDF Status: Published Journal Publication published 13 Jul, 2024 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4215383","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":292393609,"identity":"638f8e95-1d28-4676-8294-129b8841b5ca","order_by":0,"name":"Bin Zhang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAy0lEQVRIiWNgGAWjYBACAwYeEGXDwNgApHhI0JImQbKWwxJgHlFazPnPHvxc8Ot8HfOMBMYHb9sY5M0JabFsOJcsPbPvtgTjjARmw7ltDIY7Gwg57GCPgTRvD1gLmzRvG0OCwQFCWg7zGP/m7TkH0sL+mzgtx3jMpHl+HADbwkyUFsseHjNr3oZkycaeh82Sc85JGG4gpMWc/4zxbZ4/dvyG7ckHP7wps5EnaAsYMLYxMBg2gCNTghj1IPCHgUGeWLWjYBSMglEw8gAADxE8LaFiNyQAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0003-0542-1819","institution":"Tianjin University","correspondingAuthor":true,"prefix":"","firstName":"Bin","middleName":"","lastName":"Zhang","suffix":""},{"id":292393610,"identity":"42bcad85-efd9-45c4-9430-f9adef9faa52","order_by":1,"name":"Li Li","email":"","orcid":"","institution":"Tianjin University","correspondingAuthor":false,"prefix":"","firstName":"Li","middleName":"","lastName":"Li","suffix":""},{"id":292393611,"identity":"768f4783-7e34-4ecc-a5db-d2a031eb58e8","order_by":2,"name":"Fanpeng Chen","email":"","orcid":"https://orcid.org/0000-0003-2684-3180","institution":"Tianjin University","correspondingAuthor":false,"prefix":"","firstName":"Fanpeng","middleName":"","lastName":"Chen","suffix":""},{"id":292393612,"identity":"5ce85684-c8b6-4641-9372-85a33eade896","order_by":3,"name":"Chuanqi Cheng","email":"","orcid":"https://orcid.org/0000-0002-3366-8395","institution":"Tianjin University","correspondingAuthor":false,"prefix":"","firstName":"Chuanqi","middleName":"","lastName":"Cheng","suffix":""},{"id":292393613,"identity":"3a0c3408-eb45-4b5f-9804-22d786018eca","order_by":4,"name":"Yifu Yu","email":"","orcid":"https://orcid.org/0000-0002-7927-1350","institution":"Tianjin University","correspondingAuthor":false,"prefix":"","firstName":"Yifu","middleName":"","lastName":"Yu","suffix":""},{"id":292393614,"identity":"36eb53e7-e5a8-4957-b56c-b98d3f09eda7","order_by":5,"name":"Bo-Hang Zhao","email":"","orcid":"","institution":"Tianjin University","correspondingAuthor":false,"prefix":"","firstName":"Bo-Hang","middleName":"","lastName":"Zhao","suffix":""}],"badges":[],"createdAt":"2024-04-04 02:55:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4215383/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4215383/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41467-024-50335-8","type":"published","date":"2024-07-13T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":54895512,"identity":"a7bf7f6d-ba40-4def-b6ea-43a9e16a3400","added_by":"auto","created_at":"2024-04-18 08:53:22","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3160628,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eReasons and principles for the design of Cu-PCC catalysts. a\u003c/strong\u003e The performance of the ESAE under different C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e concentrations at a current density of 200 mA cm\u003csup\u003e−2\u003c/sup\u003e over commercial Cu nanoparticles. \u003cstrong\u003eb\u003c/strong\u003e Illustration of the principles of our proposed strategy.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4215383/v1/15d718dab550a17904dd39d5.png"},{"id":54895503,"identity":"0386e8f7-3681-4f9c-9dde-67238da4a4ae","added_by":"auto","created_at":"2024-04-18 08:53:17","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":3144067,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTheoretical prediction of the C\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e enrichment ability of carbon support with concave surfaces. a\u003c/strong\u003e Projected crystal orbital Hamilton population (−pCOHP) for the C–C interaction of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e. \u003cstrong\u003eb\u003c/strong\u003e −pCOHP for the C–C interaction of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e on PCC and C. \u003cstrong\u003ec\u003c/strong\u003e the adsorption of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e on PCC and C. \u003cstrong\u003ed\u003c/strong\u003e C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e migration pathway illustration. \u003cstrong\u003ee\u003c/strong\u003e The energy barriers of Cu-PCC and Cu-C.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4215383/v1/28e117e101f2e4d7b8316aa3.png"},{"id":54895505,"identity":"502aeba9-ade4-4bdb-b0c7-e60802b5e2c1","added_by":"auto","created_at":"2024-04-18 08:53:18","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":5312985,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSynthesis and Characterization of Cu-PCC and Cu-C. a\u003c/strong\u003e Schematic diagram illustrating the synthetic process of Cu-PCC. \u003cstrong\u003eb-e\u003c/strong\u003e STEM and corresponding TEM images of Cu-PCC (\u003cstrong\u003eb and c\u003c/strong\u003e) and Cu-C (\u003cstrong\u003ed and e\u003c/strong\u003e). STEM scale bar, 400 nm; TEM scale bar, 10 nm. \u003cstrong\u003ef\u003c/strong\u003e The height distributions of Cu-PCC and Cu-C obtained from the AFM images. \u003cstrong\u003eg\u003c/strong\u003e C 1s XPS spectra of Cu-PCC and Cu-C. \u003cstrong\u003eh\u003c/strong\u003e C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e-TPD of Cu-PCC and Cu-C.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4215383/v1/05011d569ea7a752856ec21b.png"},{"id":54895521,"identity":"f8f5d4b7-8353-4c26-9052-199c799debb8","added_by":"auto","created_at":"2024-04-18 08:53:23","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2340458,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eESAE reaction analysis over Cu-PCC and Cu-C. a\u003c/strong\u003e Schematic illustration of the equipment used in the DEMS analysis. \u003cstrong\u003eb and c\u003c/strong\u003e LSV curves and the corresponding DEMS signals of Cu-PCC and Cu-C. \u003cstrong\u003ed and e\u003c/strong\u003e Square wave potentials and the corresponding DEMS signals of Cu-PCC and Cu-C.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4215383/v1/fdd86e85a052ff28178396aa.png"},{"id":54895508,"identity":"41cc2025-80e6-482c-9b94-5309b32273e6","added_by":"auto","created_at":"2024-04-18 08:53:19","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1791865,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe performance evolution. a and b\u003c/strong\u003e Potential-dependent conversion (con.) of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e and FE of the obtained products over Cu-PCC and Cu-C. \u003cstrong\u003ec\u003c/strong\u003e The C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e yield normalized to the ECSA and Cu loading capacity. \u003cstrong\u003ed\u003c/strong\u003e Performance evaluation under different C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e concentrations. (The shaded areas represent the 95% confidence intervals.) \u003cstrong\u003ee\u003c/strong\u003e Potential fluctuation test of Cu-PCC and Cu-C. \u003cstrong\u003ef\u003c/strong\u003e Continuous test of the Cu-PCC.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4215383/v1/57905cecfec5d6738cd1cc36.png"},{"id":54895519,"identity":"4dc870d3-09c5-4b8b-998c-a26798d985fe","added_by":"auto","created_at":"2024-04-18 08:53:23","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":2946949,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe exploration of the origin of performance enhancement. a and b\u003c/strong\u003e The position and intensity comparison of the characteristic peaks of potential-dependent \u003cem\u003ein situ\u003c/em\u003e ATR-FTIR spectra of H\u003csub\u003e2\u003c/sub\u003eO and C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e species over Cu-C and Cu-PCC. \u003cstrong\u003ec and d\u003c/strong\u003e \u003cem\u003eIn situ\u003c/em\u003e Raman spectra of Cu-PCC and Cu-C using C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e as the feeding gas. \u003cstrong\u003ee\u003c/strong\u003e The area ratio of adsorbed C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e to H\u003csub\u003e2\u003c/sub\u003eO at different potentials over Cu-PCC and Cu-C. \u003cstrong\u003ef\u003c/strong\u003e Free-energy diagram for the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e hydrogenation process under different C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e coverages. \u003cstrong\u003eg\u003c/strong\u003e Schematic illustration of the mechanism for the enhanced C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e selectivity over Cu-PCC.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4215383/v1/b92f209665b8755f5bd088f0.png"},{"id":60241227,"identity":"935bf4af-059e-46e4-a348-48dc493a7250","added_by":"auto","created_at":"2024-07-14 07:08:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":29534063,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4215383/v1/70c6ce7a-694a-4d32-9f26-de7e035d34b8.pdf"},{"id":54895499,"identity":"d02f7f9d-30f7-414f-98d5-ae2efbd5c292","added_by":"auto","created_at":"2024-04-18 08:53:11","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":22677440,"visible":true,"origin":"","legend":"\u003cp\u003eSUPPLEMENTARY INFO\u003c/p\u003e","description":"","filename":"LLXZBHNat.Commun.SI.docx","url":"https://assets-eu.researchsquare.com/files/rs-4215383/v1/51a9e7d7f16a81702337cc49.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Concave surface-enriched reactant and enhanced mass transfer for electrocatalytic ethylene production from low-concentrated acetylene","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe production of the essential chemical ethylene (C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e) is highly dependent on high-temperature naphtha cracking, which relies on petroleum resources with excess carbon emissions.\u003csup\u003e1,2\u003c/sup\u003e Hence, developing a petroleum-independent and mild strategy for C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e production is highly desirable for a low-carbon economy.\u003csup\u003e3\u0026ndash;8\u003c/sup\u003e Recently, the electrocatalytic semihydrogenation of coal-derived acetylene (C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e) to ethylene (ESAE) strategy has been developed.\u003csup\u003e7,8\u003c/sup\u003e Inhibiting the competing hydrogen evolution reaction (HER) at an industrial current density (\u0026ge;\u0026thinsp;200 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e) is pivotal for the economic potential of the ESAE strategy. At present, both the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e Faradaic efficiency (FE) and the optimal current density are extremely low for low-concentration C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e hydrogenation (e.g., ˂50% FE at 60 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e for ~\u0026thinsp;1% C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e impurity hydrogenation in C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e), which is far from the target of practical C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e production.\u003csup\u003e7\u003c/sup\u003e Additionally, the cost of separating and concentrating C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e feed gas accounts for a large proportion of the total C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e production cost.\u003csup\u003e8\u003c/sup\u003e Consequently, the cost of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e production would further decrease if the raw tail gas (~\u0026thinsp;15% C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e) from the arc-plasma process of coal could be directly used as feedstock for the ESAE process.\u003csup\u003e8\u0026ndash;13\u003c/sup\u003e However, the HER dominates the whole process as the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e concentration decreases (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). Therefore, further development of highly efficient and selective catalysts for converting raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e into C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e with high selectivity and conversion rates is urgently needed.\u003c/p\u003e \u003cp\u003eGenerally, for a gas-involved reaction, enriching its local concentration and boosting the mass transfer toward active sites are important for enhancing the reactant\u0026rsquo;s partial pressure to improve the activity and selectivity.\u003csup\u003e14\u0026ndash;17\u003c/sup\u003e Copper (Cu) nanoparticles have been proven to be an appropriate choice for suppressing the competing HER under high C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e partial pressure.\u003csup\u003e18\u0026ndash;21\u003c/sup\u003e Thus, the critical issue for the selective conversion of raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e lies in enriching the concentration and guaranteeing the facile mass transfer of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e around the surface of the Cu nanoparticles. Structures with high curvatures always lead to a high local electric field, which can gather reactants around the catalyst surface and increase its concentration.\u003csup\u003e22\u0026ndash;26\u003c/sup\u003e For example, Liu \u003cem\u003eet al\u003c/em\u003e. demonstrated that Cu nanoneedles could increase the adsorption of the *CO intermediate and, in turn, accelerate C\u0026ndash;C coupling during the electrocatalytic CO\u003csub\u003e2\u003c/sub\u003e reduction process \u003csup\u003e23\u003c/sup\u003e. In addition to the tips, the concave surface also has a high curvature.\u003csup\u003e27\u0026ndash;29\u003c/sup\u003e Moreover, carbon-based supports with porous structures could effectively boost gas capture and transport, benefitting mass transfer.\u003csup\u003e30\u0026ndash;32\u003c/sup\u003e In this regard, Cu nanoparticles loaded on porous carbon supports with abundant nanosized concave surfaces (denoted as Cu-PCC) are expected to be efficient at increasing the concentration and increasing the mass transfer of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e around Cu sites through the unique concave support, consequently suppressing the HER under low-concentration raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). However, the synthesis and exploration of porous concave carbon-supported Cu nanoparticle electrodes for electrocatalytic C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e production are lacking.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHerein, a preliminary density functional theory (DFT) calculation was first conducted to show that a concave surface is beneficial for the enrichment and facile mass transfer of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e, increasing its partial pressure around the active sites. Then, we designed a facile self-template method to synthesize Cu-PCC, which was found to be an outstanding electrocatalyst for the ESAE process, using simulated raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e as feedstocks. Cu-PCC delivered a C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e FE of 91.70% and a single-pass C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e conversion of 56.31% at a potential of \u0026minus;\u0026thinsp;1.2 V versus a reversible hydrogen electrode (vs. RHE) at a partial current density of 0.42 A cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, greatly outperforming the Cu nanoparticles supported on carbon without a concave surface counterpart. Moreover, C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e temperature-programmed desorption (C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e-TPD) and \u003cem\u003ein situ\u003c/em\u003e spectroscopic characterization experiments revealed that the polarization field induced by the concave surface over Cu-PCC increased C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e coverage and strengthened the intermolecular \u003cem\u003eπ\u003c/em\u003e-conjugation of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e, thus leading to the delocalization of the \u003cem\u003eπ\u003c/em\u003e electrons of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e to promote the activation of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e and enhance the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e selectivity of the ESAE with raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eThe design and synthesis of electrocatalyst\u003c/h2\u003e\n\u003cp\u003eWe first conducted DFT calculations to evaluate the local field induced by the concave surface. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea, the electrons are enriched at the concave carbon surfaces to build a polarization field, which could enhance the conjugation between C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e and the negative center (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb and Supplementary Fig.\u0026nbsp;1), thus leading to the downshifting of the bonding orbital and benefiting the enrichment of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec).\u003csup\u003e21,29,33\u003c/sup\u003e Once the low-concentration C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e accumulated on the concave carbon surfaces, facile migration to the Cu sites was still a prerequisite for the following reaction. In that case, simulations of the migration pathway of the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e molecule in solution over the Cu-C and Cu-PCC interfaces were conducted (Supplementary Figs.\u0026nbsp;2\u0026ndash;3). For gas-involved reactions, there will be a few layers of water clusters (WC) due to the hydrogen bonding network around the gas‒solid-liquid three-phase interface and the gap between the WC and solid surface (labeled \u003cem\u003ed\u003c/em\u003e in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed) provides a diffusion channel for gaseous reactants. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed, the diffusion channel for Cu-PCC is larger than that for Cu-C, thus leading to a straight-line migration pathway rather than a distorted pattern over the counterpart. The associated migration energy barriers were calculated, as shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ee. The maximum migration energy for C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e diffusion over Cu-PCC is 0.41 eV, which is much lower than that of Cu\u0026minus;C (1.23 eV), indicating that the mass transfer of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e is significantly greater over the concave surface. These theoretical results indicate that a carbon support with concave surfaces could efficiently gather low-concentration raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e feedstocks and increase the mass transfer kinetics for subsequent hydrogenation over Cu sites.\u003c/p\u003e\n\u003cp\u003eGenerally, the collapse and reconstruction of a surface increases the roughness and results in many nanosized concave surfaces.\u003csup\u003e34,35\u003c/sup\u003e Thus, a sequential self-template transformation method based on the Kirkendall effect was proposed for the synthesis of Cu-PCC (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea).\u003csup\u003e36,37\u003c/sup\u003e Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the successful preparation of Cu-based metal-organic framework precursors (Cu-MOF) with planar surfaces and octahedral-like morphologies (Supplementary Fig.\u0026nbsp;4). After the reaction of Cu-MOF precursors with tannic acid (TA), the octahedron-like shapes can be maintained, and the surface collapses inward (denoted as Cu-TA, Supplementary Fig.\u0026nbsp;5). After the annealing of Cu-TA under an H\u003csub\u003e2\u003c/sub\u003e atmosphere, the wall of the Cu-TA complex was converted into porous carbon with abundant nanosized concave surfaces, as confirmed by scanning transmission electron microscopy (STEM), SEM, and TEM images (Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb, c and Supplementary Fig.\u0026nbsp;6).\u003csup\u003e38\u003c/sup\u003e However, Cu-C directly calcinated from Cu-MOF precursors without the collapse process exhibited a planar carbon surface (Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ed, e and Supplementary Fig.\u0026nbsp;7). Moreover, the atomic force microscopy (AFM) images also demonstrated the rougher surface of Cu-PCC caused by these concave surfaces compared to that of Cu-C (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ef). In addition, X-ray diffraction (XRD) patterns, Fourier transform infrared (FTIR) spectra, and Raman spectra were obtained to monitor the sequential conversion process from Cu-MOF precursors to Cu-TA and eventually to Cu-PCC (Supplementary Fig.\u0026nbsp;8). The Raman, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) results show that there are no other differences between Cu-PCC and Cu-C, other than the nanosized concave surfaces over the PCC supports (Supplementary Figs.\u0026nbsp;9\u0026ndash;11). Note that the negative shift in the binding energies of C-O and C\u0026thinsp;=\u0026thinsp;O over Cu-PCC compared to that over Cu-C verifies the existence of a polarization field (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eg).\u003csup\u003e39\u0026ndash;41\u003c/sup\u003e Furthermore, C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e-TPD was employed to evaluate the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e gas enrichment ability of Cu-PCC.\u003csup\u003e42\u003c/sup\u003e The greater C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e adsorption on Cu-PCC than on its Cu-C counterpart, along with the ever-increasing desorption temperature under similar specific surface areas (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eh and Supplementary Fig.\u0026nbsp;12), indicated that the enriched C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e and optimized mass transfer were the main reasons for the enhanced interactions between the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e feedstocks and Cu-PCC.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n\u003ch2\u003eESAE reaction analysis and performance evaluation\u003c/h2\u003e\n\u003cp\u003eThe ESAE process was evaluated in a three-electrode flow cell with a gas diffusion layer under potentiostatic conditions using simulated raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e (~\u0026thinsp;15%) as the feeding gas. First, online differential electrochemical mass spectrometry (DEMS) was conducted under linear sweep voltammetry (LSV) mode to explore and analyze the ESAE process (Fig.\u0026nbsp;4a). In addition to Cu-PCC possessing a more positive onset potential for C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e hydrogenation (\u0026minus;\u0026thinsp;0.06 V vs. RHE) than Cu-C (\u0026minus;\u0026thinsp;0.1 V vs. RHE), Cu-PCC has a much more negative HER onset potential, endowing Cu-PCC with a better ability to activate C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e and suppress the HER (Figs.\u0026nbsp;4b, c and Supplementary Figs.\u0026nbsp;13\u0026ndash;14). Moreover, the signal intensity of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e over Cu-C displays a nearly\u0026nbsp;volcanic shape, and the response of H\u003csub\u003e2\u003c/sub\u003e acutely increases under potentials more negative than \u0026minus;\u0026thinsp;0.6 V vs. RHE. However, the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e signal always dominated the whole product until the end of the LSV over Cu-PCC. In other words, the production gap between C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e and the H\u003csub\u003e2\u003c/sub\u003e byproduct becomes larger with decreasing potential over Cu-PCC, while it shows an inverse trend over Cu-C, further verifying the superiority of Cu-PCC in the ESAE process. In addition, the same electron transfer number of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e to C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO to H\u003csub\u003e2\u003c/sub\u003e is likely the reason for the similar LSV curves of the two catalysts. Then, we performed the DEMS test under square wave potentials. For Cu-PCC, H\u003csub\u003e2\u003c/sub\u003e emerges under a much more negative potential than does its Cu-C counterpart. In addition, unlike the almost unchanged or even decreased C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e signal observed for Cu-C, the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e signal increases with decreasing potential, indicating better C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e selectivity in Cu-PCC under a raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e atmosphere (Figs.\u0026nbsp;4d, e).\u003c/p\u003e\n\u003cp\u003eThe quantification of the ESAE process showed that the FE of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e over Cu-PCC exceeded\u0026thinsp;~\u0026thinsp;90%, and the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e6\u003c/sub\u003e byproduct was almost undetectable throughout the whole range (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea). However, the FE of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e decreased rapidly, with more H\u003csub\u003e2\u003c/sub\u003e produced at more negative potentials than \u0026minus;\u0026thinsp;0.8 V vs. RHE over Cu-C (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eb). Furthermore, the obtained C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e production rate of Cu-PCC at a potential of \u0026minus;\u0026thinsp;1.2 V vs. RHE was 3.42 mol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with a partial current density and C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e conversion of 0.42 A cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and 56.31%, respectively, greatly surpassing those of its Cu-C counterpart (2.00 mol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 0.26 A cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and 33.21% C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e conversion) (Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea, b). The superiority of the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e production rates of Cu-PCC became more obvious after normalization by the electrochemical surface area (ECSA) or Cu loading capacity (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ec, and Supplementary Figs.\u0026nbsp;15\u0026ndash;17). In addition, considering the demand for industrial production, stability evaluation experiments at various concentrations and step potentials for the hydrogenation of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e were performed. Accordingly, the 95% confidence intervals of FEs were calculated to evaluate the selectivity stability, as shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ed. The narrower confidence intervals of the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e FEs over Cu-PCC than Cu-C demonstrate that the fitted lines of FEs under different concentrations of Cu-PCC are more precise,\u003csup\u003e43\u003c/sup\u003e which means that the influence of concentration on FEs is less significant over Cu-PCC,\u003csup\u003e44\u003c/sup\u003e indicating its better stability. In addition, the FE and selectivity of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e remain unchanged at different potentials over Cu-PCC, which is superior to its counterpart (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ee). These results indicate that the proposed Cu-PCC exhibits potential- and concentration-independent ESAE activity, which is suitable for practical application. Note that both the FE of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e and the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e conversion over Cu-PCC remained unchanged within the error range during the 12 h continuous test, suggesting its robust durability (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ef and Supplementary Fig.\u0026nbsp;18).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n\u003ch2\u003eMechanistic exploration of the high selectivity for ethylene\u003c/h2\u003e\n\u003cp\u003eTo elucidate the reason for the increase in C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e FE and selectivity over Cu-PCC under a raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e atmosphere, \u003cem\u003ein situ\u003c/em\u003e attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and Raman spectroscopies were used to evaluate the status and coverage of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e with the catalytic surface (Supplementary Figs.\u0026nbsp;19\u0026ndash;20). Generally, the peak frequency of the IR or Raman characteristic peak is determined by the strength of the corresponding bond.\u003csup\u003e45\u0026ndash;48\u003c/sup\u003e For C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e, the enhanced \u003cem\u003e\u0026pi;\u003c/em\u003e conjugation led to the redistribution of bonding electrons, and the corresponding \u003cem\u003e\u0026pi;\u003c/em\u003e bond was weakened due to the delocalization of electrons, consequently leading to a negative shift in the peak frequency (redshift).\u003csup\u003e49\u003c/sup\u003e As shown in Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea, b, both \u003cem\u003e\u0026nu;\u003c/em\u003e(C-H) (~\u0026thinsp;3200 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and \u003cem\u003e\u0026nu;\u003c/em\u003e(C\u0026thinsp;\u0026equiv;\u0026thinsp;C) (~\u0026thinsp;1620 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e over Cu-PCC shift to lower frequencies than do their Cu-C counterparts at each potential (Supplementary Figs.\u0026nbsp;21, 22),\u003csup\u003e7,8,50,51\u003c/sup\u003e indicating that the triple bond of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e becomes unstable over Cu-PCC due to the delocalization of \u003cem\u003e\u0026pi;\u003c/em\u003e electrons; thus, the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e molecule is easier to activate. Moreover, the redshift of the peak attributed to adsorbed C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e in the Raman spectrum from 1700 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e over Cu-C to 1685 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e over Cu-PCC also confirmed the attenuation of the \u003cem\u003e\u0026pi;\u003c/em\u003e bonds of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e, further demonstrating that support with concave surfaces is beneficial for C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e activation (Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ec, d).\u003csup\u003e20,21\u003c/sup\u003e In addition, considering that the integrals of the IR bands are related to the coverage of the respective adsorbate on the surface, the area ratio between \u003cem\u003e\u0026nu;\u003c/em\u003e(C\u0026thinsp;\u0026equiv;\u0026thinsp;C) and \u003cem\u003e\u0026delta;\u003c/em\u003e(H-O-H) was viewed as the descriptor of the relative coverage of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e over the catalyst surface. The plot of \u003cem\u003e\u0026nu;\u003c/em\u003e(C\u0026thinsp;\u0026equiv;\u0026thinsp;C)/\u003cem\u003e\u0026delta;\u003c/em\u003e(H-O-H) over Cu-C exhibited a volcano-like profile, which began to decrease at potentials more negative than \u0026minus;\u0026thinsp;0.2 V vs. RHE, indicating that H\u003csub\u003e2\u003c/sub\u003eO adsorption improved with the negative shift potential and accounted for the strong HER competition. Conversely, the plot of \u003cem\u003e\u0026nu;\u003c/em\u003e(C\u0026thinsp;\u0026equiv;\u0026thinsp;C)/\u003cem\u003e\u0026delta;\u003c/em\u003e(H-O-H) over Cu-PCC presented a nearly monotonically increasing trend with negatively shifted potentials (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ee), demonstrating the higher C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e coverage of Cu-PCC under the applied potential range and accounting for the enhanced intermolecular \u003cem\u003e\u0026pi;\u003c/em\u003e conjugation and the delocalization of \u003cem\u003e\u0026pi;\u003c/em\u003e electrons from C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e.\u003csup\u003e52\u003c/sup\u003e Finally, we also conducted DFT calculations to evaluate the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e hydrogenation energy barrier under high and low coverage to verify our experimental results. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ef, the hydrogenation barriers under high C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e coverage are lower than those under low coverage (Supplementary Figs.\u0026nbsp;23\u0026ndash;27), indicating easier activation of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e and better hydrogenation kinetics over Cu-PCC. Accordingly, the in-depth origins for the enhanced C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e selectivity obtained using low-concentration raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e over Cu-PCC are summarized in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eg. The C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e feedstocks could be enriched by the nanosized concave carbon surfaces and then effectively transferred to the Cu sites, consequently resulting in high C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e partial pressure and coverage. Then, the electron delocalization effect due to the increased C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e coverage promoted C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e activation, thus leading to satisfactory C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e selectivity and FE over Cu-PCC.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn summary, Cu nanoparticles loaded on carbon supports with abundant nanosized concave surfaces were designed to enhance C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e adsorption for direct utilization of raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e. Cu-PCC delivered a C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e FE of 91.7% and a single-pass C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e conversion of 56.31% under a potential of \u0026minus;\u0026thinsp;1.2 V vs. RHE at a partial current density of 0.42 A cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, greatly outperforming its counterpart without the concave surface. Notably, the nanosized concave surfaces were significantly enriched in C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e gas and had lower mass transfer kinetics, resulting in higher C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e coverage. Moreover, the delocalization of \u003cem\u003e\u0026pi;\u003c/em\u003e electrons in C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e due to the strengthened intermolecular \u003cem\u003e\u0026pi;\u003c/em\u003e conjugation caused by the increased C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e coverage promoted the activation of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e, thus endowing Cu-PCC with robust HER suppression ability and better C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e selectivity. Our work may not only demonstrate an efficient and selective catalyst for nonpetroleum C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e electrosynthesis but also open a facile way to access low-concentration gaseous reactants for various catalytic applications.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eSynthesis of Cu-MOF precursors.\u003c/strong\u003e According to previous literature\u003csup\u003e37\u003c/sup\u003e, the Cu-MOF precursors were prepared by a PVP-assisted strategy as follows. First, 1.46 g of Cu(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026middot;3H\u003csub\u003e2\u003c/sub\u003eO and 0.7 g of H\u003csub\u003e3\u003c/sub\u003eBTC were dissolved in 20 mL of DMF to form solution A and solution B, respectively. Subsequently, 0.5 g PVP was added to solution A and stirred for 5 min to obtain a homogenous solution. Then, solution B was mixed with solution A and stirred for an additional 10 min. Afterward, the mixture was transferred to a 100 mL Teflon-lined stainless-steel autoclave and maintained at 80\u0026deg;C for 24 h. Finally, the blue precipitates were harvested by centrifugation, washed with DIW and ethanol several times, and dried in a vacuum oven overnight to produce the Cu-MOF precursors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSynthesis of Cu-TA.\u003c/strong\u003e The as-prepared Cu-MOF precursors (100 mg) and tannic acid (TA) (50 mg) were first dispersed into 50 mL of DIW to form two solutions. The two solutions were subsequently mixed at room temperature and stirred for 30 min. Afterward, the mixture was put into an oil bath at 50\u0026deg;C and refluxed under continuous magnetic stirring (stirring speed: 700 rpm) for 7 h. The precipitate was then washed with DIW and absolute ethanol at least three times to remove the residual TA and dried at 70\u0026deg;C in a vacuum oven overnight.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSynthesis of Cu-PCC and Cu-C.\u003c/strong\u003e To obtain Cu-PCC and Cu-C, the as-prepared Cu-TA and Cu-MOF precursors were annealed at 400\u0026deg;C for 2 h at a heating rate of 5\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e under a 3% H\u003csub\u003e2\u003c/sub\u003e/Ar atmosphere. The mixture was then naturally cooled to room temperature.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eGeneral characterizations.\u003c/strong\u003e Quasi-\u003cem\u003ein situ\u003c/em\u003e powder X-ray diffraction (XRD) was performed on a Bruker D8 Focus Diffraction System (Germany) using a Cu \u003cem\u003eK\u003c/em\u003e\u0026alpha; radiation source (\u0026lambda;\u0026thinsp;=\u0026thinsp;0.154178 nm). Scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) were conducted with an FEI Apreo S LoVac microscope (10 kV). Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images were obtained with a JEOL-2100F system equipped with an EDAX Genesis XM2. X-ray photoelectron spectroscopy (XPS) was conducted with a PHI-1600 X-ray photoelectron spectrometer equipped with Al \u003cem\u003eK\u003c/em\u003e\u0026alpha; radiation. All the peaks were calibrated with the Ti 2p spectrum since C 1s is a key parameter in our research. The Raman spectra were obtained with a Renishaw inVia reflex Raman microscope under excitation with a 514 nm laser at a power of 20 mW. Fourier transform infrared spectroscopy (FTIR) was performed on a Nicolet IS50 instrument. The Brunauer\u0026ndash;Emmett\u0026ndash;Teller (BET) surface area was measured by N\u003csub\u003e2\u003c/sub\u003e adsorption using a Micromeritics ASAP 2460. Inductively coupled plasma‒optical emission spectrometry (ICP‒OES) was conducted with an Agilent 5110 instrument (OES). Atomic Force Microscope (AFM) was carried out on a Bruker Dimension Icon.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eElectrochemical measurements in the flow cell.\u003c/strong\u003e Electrochemical measurements were carried out in a typical flow cell consisting of a GDL as the working electrode, Pt foil as the counter electrode, and Hg/HgO as the reference electrode using a CS150H electrochemical workstation. The cathode cell and anode cell were separated by a Nafion 117 proton exchange membrane. The cathode and anode electrolytes were both composed of 1.0 M KOH solution, and a peristaltic pump was used to circulate the liquid phase. The gas flow rate was controlled by a mass flowmeter. Before the performance tests, the working electrode was fixed at the interface between the gas flow block and the cathodic electrolyte block by conductive copper tape. First, the electrochemical semihydrogenation of acetylene was conducted at different applied potentials for 10\u0026ndash;20 min to achieve relatively stable and reliable performance parameters before quantitative analysis. The gas at the flow cell outlet was directly introduced into the gas chromatography system for analysis of the products. All the LSV curves were \u003cem\u003eiR\u003c/em\u003e compensated with a compensation level of 70%. For the Tafel slopes, the LSV curves were replotted by using the logarithms of the current density as the x-axis and the potential as the y-axis. The obtained slopes of the linear part of the replotted figure were the Tafel slopes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eQuantitative analysis of the C\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u0026nbsp;\u003c/sub\u003e \u003cstrong\u003econversion, evolution rate, and FE of the obtained products.\u003c/strong\u003e The products were subjected to a GC-2010 gas chromatograph equipped with an activated carbon-packed column (with He as the carrier gas) and a barrier discharge ionization detector. The C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e conversion and evolution rate of the different products were calculated using equations (1) and (2), and the FEs of the different products were calculated using Eq.\u0026nbsp;(3). All the experiments were repeated three times.\u003c/p\u003e\n\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\n \u003cdiv id=\"FileID_Equa\" class=\"mathdisplay\"\u003e$$\\text{Conversion }\\left(\\text{%}\\right)\\text{ = }\\frac{\\text{the peak area of B-peak area of A}}{\\text{the peak area of B}}\\text{ \u0026times;100% (1) }$$\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\n \u003cdiv id=\"FileID_Equb\" class=\"mathdisplay\"\u003e$$\\text{Evolution Rate (}\\text{mmol}\\text{/mg/h)=}\\frac{\\text{the peak area of X \u0026times;}\\text{C}}{\\text{the peak area of standard }\\text{gas\u0026times;}\\text{m}\\text{ }}\\text{ \u0026times; }\\text{S }\\text{ (2)}$$\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\n \u003cdiv id=\"FileID_Equc\" class=\"mathdisplay\"\u003e$${\\text{FE}}_{\\text{X}}\\left(\\text{%}\\right)\\text{=}\\frac{\\text{a \u0026times; }{\\text{n}}_{\\text{X}}\\text{ \u0026times;}\\text{F}}{\\text{Q}} \\text{(3)}$$\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eX: The different products, including H\u003csub\u003e2\u003c/sub\u003e, C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e, and C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e6\u003c/sub\u003e.\u003c/p\u003e\n\u003cp\u003eC:\u0026nbsp;The concentration of X in standard gas.\u003c/p\u003e\n\u003cp\u003em:\u0026nbsp;The mass of catalysts over the electrode.\u003c/p\u003e\n\u003cp\u003en:\u0026nbsp;The moles of different products, including H\u003csub\u003e2\u003c/sub\u003e, C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e, and C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e6\u003c/sub\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eA\u003c/em\u003e: Area of the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e outlet; B: area of the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e inlet.\u003c/p\u003e\n\u003cp\u003eS:\u0026nbsp;The gas flow rate.\u003c/p\u003e\n\u003cp\u003ea:\u0026nbsp;The electron transfer number.\u003c/p\u003e\n\u003cp\u003eF:\u0026nbsp;Faraday constant.\u003c/p\u003e\n\u003cp\u003eQ:\u0026nbsp;The total Coulomb number of the ESAE process.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eElectrochemical\u003c/strong\u003e \u003cstrong\u003eoperando\u003c/strong\u003e \u003cstrong\u003eonline DEMS analysis.\u003c/strong\u003e \u003cem\u003eOperando\u003c/em\u003e online DEMS analysis was conducted with a QAS 100 instrument provided by Linglu Instruments (Shanghai) Co., Ltd. Because the products in the proposed ESAE process were all in the gas phase, \u003cem\u003eoperando\u003c/em\u003e experiments were conducted to monitor the distribution of the products during the on-stream reaction, clarifying the selectivity issues more directly and clearly. The flow cell used in the performance evaluation and the DEMS were coupled to ensure that the gas at the flow cell outlet was directly injected into the negatively pressured gas circuit system of the DEMS through a quartz capillary that was inserted into the outlet of the flow cell. The LSV test and rectangular wave potentials were applied from \u0026minus;\u0026thinsp;0.6 to \u0026minus;\u0026thinsp;1.2 V vs. RHE with a constant interval of 400 s using a CS150H electrochemical workstation. During the experiment, the flow rates of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e gas and the electrolyte were set the same as those used for the performance evaluation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eElectrochemical\u003c/strong\u003e \u003cstrong\u003ein situ\u003c/strong\u003e \u003cstrong\u003eATR-FTIR measurements.\u003c/strong\u003e \u003cem\u003eIn situ\u003c/em\u003e ATR-FTIR was performed on a Nicolet 6700 FTIR spectrometer equipped with an MCTA detector with silicon as the prismatic window and an ECIR-II cell by Linglu Instruments. First, Cu-PCC was carefully dropped on the surface of the gold film, which was chemically deposited on the surface of the silicon prismatic material before each experiment. Then, the deposited silicon prismatic material served as the working electrode. Pt foil and Hg/HgO with an internal reference electrolyte of 1.0 M KOH were used as the counter and reference electrodes, respectively. A 1 M KOH solution was used as the electrolyte. The electrolyte was presaturated with pure C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e gas, and the gas was continuously bubbled through during the whole measurement. The spectrum was recorded every 30 s under an applied potential ranging from 0.2 to \u0026minus;\u0026thinsp;1.0 V vs. RHE.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eElectrochemical\u003c/strong\u003e \u003cstrong\u003ein situ\u003c/strong\u003e \u003cstrong\u003eRaman measurements.\u003c/strong\u003e \u003cem\u003eIn situ\u003c/em\u003e electrochemical Raman spectra were recorded via an electrochemical workstation on a Renishaw inVia reflex Raman microscope under 532 nm laser excitation under controlled potentials. We used a homemade Teflon electrolytic cell equipped with a piece of round quartz glass for the incidence of lasers and protection of the tested samples1. Before the experiments, the electrolyte was pretreated with pure C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e gas to obtain C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e-saturated KOH. The working electrode was parallel to the quartz glass to maintain the plane of the sample perpendicular to the incident laser. The Pt wire was rolled to a circle around the working electrode to serve as the counter electrode. The reference electrode was Hg/HgO with an internal reference electrolyte of 1.0 M KOH. The spectrum was recorded under applied potentials ranging from 0.2 to \u0026minus;\u0026thinsp;1.0 V vs. RHE.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComputational details.\u003c/strong\u003e All the DFT calculations were performed using the Vienna ab initio simulation package (VASP). \u003csup\u003e53\u003c/sup\u003e The projector augmented wave (PAW) pseudopotential with the PBE generalized gradient approximation (GGA) exchange-correlation function was utilized in computations .\u003csup\u003e54,55\u003c/sup\u003e The cutoff energy of the plane wave basis set was 500 eV, and a Monkhorst-Pack mesh of 3\u0026times;3\u0026times;1 was used in K-sampling for the adsorption energy calculations and other nonself-consistent calculations. The long-range dispersion interaction was described by the DFT-D3 method. The electrolyte was incorporated implicitly with the Poisson-Boltzmann model implemented in VASPsol \u003csup\u003e56\u003c/sup\u003e. The relative permittivity of the media was chosen to be ϵ\u003csub\u003er\u003c/sub\u003e = 78.4, corresponding to that of water. All atoms were fully relaxed with an energy convergence tolerance of 10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e eV per atom, and the final force on each atom was \u0026lt;\u0026thinsp;0.05 eV \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe transition state (TS) searches were performed using the Dimer method in the VTST package. The final force on each atom was \u0026lt;\u0026thinsp;0.1 eV \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e. The TS search is conducted by using the climbing-image nudged elastic band (CI-NEB) method to generate initial guess geometries, followed by the dimer method to converge to the saddle points.\u003c/p\u003e\n\u003cp\u003eThe adsorption energy of the reaction intermediates can be computed using Eqs. (4)-(5):\u003c/p\u003e\n\u003cp\u003e∆\u003cem\u003eE\u003c/em\u003e = \u003cem\u003eE\u003c/em\u003e\u003csub\u003e*ads\u003c/sub\u003e - (\u003cem\u003eE\u003c/em\u003e\u003csub\u003e*\u0026nbsp;\u003c/sub\u003e+ \u003cem\u003eE\u003c/em\u003e\u003csub\u003eads\u003c/sub\u003e) \u0026nbsp; (4)\u003c/p\u003e\n\u003cp\u003e∆\u003cem\u003eG\u003c/em\u003e\u003csub\u003e\u0026nbsp;\u003c/sub\u003e= ∆\u003cem\u003eE\u003c/em\u003e + ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eZPE\u003c/sub\u003e - \u003cem\u003eT\u003c/em\u003e∆\u003cem\u003eS \u0026nbsp;\u003c/em\u003e(5)\u003c/p\u003e\n\u003cp\u003ewhere ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eZPE\u003c/sub\u003e is the zero-point energy change and ∆\u003cem\u003eS\u003c/em\u003e is the entropy change. In this work, the values of ∆\u003cem\u003eE\u003c/em\u003e\u003csub\u003eZPE\u003c/sub\u003e and ∆\u003cem\u003eS\u003c/em\u003e were obtained via vibration frequency calculations.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eData availability\u003c/h2\u003e\n\u003cp\u003eThe source data underlying Figs. 1\u0026ndash;6 are provided as a Source Data file. The data that support other plots within this paper are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eWe acknowledge the National Natural Science Foundation of China (Nos. 22271213 and 22209120).\u003c/p\u003e\n\u003ch2\u003eAuthor Contributions\u003c/h2\u003e\n\u003cp\u003eB. Zhang conceived the idea and directed the project. L. Li, B.-H. Zhao, and B. Zhang designed the experiments. L. Li. and F. P. Chen carried out the experiments and characterization. Y. F. Yu assisted in some experiments. C. Q. 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Phys.\u003c/em\u003e \u003cstrong\u003e140\u003c/strong\u003e, 084106, (2014).\u003c/li\u003e\n\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-4215383/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4215383/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eElectrocatalytic semihydrogenation of acetylene (C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e) provides a facile and petroleum-independent strategy for ethylene (C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e) production. However, the reliance on the preseparation and concentration of raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e hinders its economic potential. Here, density functional theory calculations demonstrate that a concave surface is beneficial for enriching C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e and optimizing its mass transfer kinetics, thus leading to a high partial pressure of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e around active sites, which is suitable for the direct conversion of raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e. Then, a porous concave carbon-supported Cu nanoparticle (Cu-PCC) electrode was designed to enrich the C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e gas around the Cu sites. As a result, the as-prepared electrode enables a 91.7% C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e Faradaic efficiency and a 56.31% C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e single-pass conversion under a simulated raw coal-derived C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e atmosphere (~\u0026thinsp;15%) at a partial current density of 0.42 A cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, greatly outperforming its counterpart without concave surface supports. The strengthened intermolecular \u003cem\u003eπ\u003c/em\u003e conjugation caused by the increased C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e coverage is revealed to result in the delocalization of \u003cem\u003eπ\u003c/em\u003e electrons in C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e, consequently promoting C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e2\u003c/sub\u003e activation, suppressing HER competition, and enhancing C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e selectivity.\u003c/p\u003e","manuscriptTitle":"Concave surface-enriched reactant and enhanced mass transfer for electrocatalytic ethylene production from low-concentrated acetylene","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-18 08:51:09","doi":"10.21203/rs.3.rs-4215383/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"61108e61-e4a0-4b43-b680-e662781e90ff","owner":[],"postedDate":"April 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":30805458,"name":"Physical sciences/Chemistry/Electrochemistry/Electrocatalysis"},{"id":30805459,"name":"Physical sciences/Chemistry/Green chemistry/Sustainability"}],"tags":[],"updatedAt":"2024-07-14T07:08:07+00:00","versionOfRecord":{"articleIdentity":"rs-4215383","link":"https://doi.org/10.1038/s41467-024-50335-8","journal":{"identity":"nature-communications","isVorOnly":false,"title":"Nature Communications"},"publishedOn":"2024-07-13 04:00:00","publishedOnDateReadable":"July 13th, 2024"},"versionCreatedAt":"2024-04-18 08:51:09","video":"","vorDoi":"10.1038/s41467-024-50335-8","vorDoiUrl":"https://doi.org/10.1038/s41467-024-50335-8","workflowStages":[]},"version":"v1","identity":"rs-4215383","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4215383","identity":"rs-4215383","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}