Abstract：
Due to the limitation of the high-value-added products obtained from electrocatalytic CO2 reduction within an acid environment, introducing additional elements can expand the diversity of the products obtained during the CO2 reduction reaction (CO2RR) and nitrogen reduction reaction (NRR). Thus, coelectroreduction of CO2 and N2 is a new strategy for producing acetamide (CH3CONH2) via both C-C and C-N bond coupling using Cu-based nitrogen-carbon nanosheets. CO2 can reduce to CO, and a key ketene (*C═C═O) can be generated from *CO*CO dimerization; this ketene is postulated as an intermediate in the formation of acetamide. However, most studies focus on promoting the C-C bond formation. Here, we propose that C-N bond coupling can form acetamide through the interaction of *C═C═O with NH3. The acetamide is formed via a nucleophilic attack between *NH3 and the *C═C═O intermediate. The C-N coupling mechanism was successfully applied to expand the variety of nitrogen-containing products obtained from CO2 and N2 coreduction. Thus, we successfully screened Cu2-based graphite and Cu-based C3N4 as catalysts that can produce C2+ compounds by integrating CO dimerization with acetamide synthesis. In addition, we observed that Cu2-based C2N and Cu-based C3N4 catalysts are suitable for the NRR. Cu-based C3N4 showed high CO2RR and NRR activities with small negative limiting potential (UL) values of -0.83 and -0.58 V compared to those of other candidates, respectively. The formation of *COHCOH from *COHCO was considered the rate-determining step (RDS) during acetamide electrosynthesis. The limiting potential value of Cu2-based C2N was only -0.46 V for NH3 synthesis, and the formation of *NNH was via the RDS via an alternating path. The adsorption energy difference analysis both CO2 and N2 compare with the hydrogen evolution reaction (HER), suggesting that Cu2-based C2N exhibited the highest CO2RR and NRR selectivity among the 13 analyzed catalysts. The results of this study provide innovative insights into the design principle of Cu-based nitrogen-carbon electrocatalysts for generating highly efficient C-N coupling products.
摘要：
由于在酸性环境中电催化CO2还原获得的高附加值产品的局限性，引入额外的元素可以扩大在CO2还原反应（CO2RR）和氮还原反应（NRR）过程中获得的产物的多样性。因此，CO2和N2的共电还原是使用Cu基氮碳纳米片通过C-C和C-N键偶联生产乙酰胺（CH3CONH2）的新策略。CO2可以还原成CO，和关键烯酮(*C=C=O)可以由*CO*CO二聚化产生;该烯酮被假定为形成乙酰胺的中间体。然而,大多数研究集中在促进C-C键的形成。这里,我们认为C-N键偶联可以通过*C=C=O与NH3的相互作用形成乙酰胺。乙酰胺通过*NH3和*C=C=O中间体之间的亲核攻击形成。C-N偶联机理已成功应用于扩展CO2和N2共还原获得的含氮产物的种类。因此，我们成功地筛选了Cu2基石墨和Cu基C3N4作为催化剂，可以通过将CO二聚与乙酰胺合成相结合来生产C2化合物。此外,我们观察到基于Cu2的C2N和基于Cu的C3N4催化剂适用于NRR。与其他候选物相比，铜基C3N4显示出较高的CO2RR和NRR活性，负限制电位（UL）值为-0.83和-0.58V，分别。由*COHCO形成*COHCOH被认为是乙酰胺电合成过程中的速率决定步骤(RDS)。基于Cu2的C2N的极限电位值仅为-0.46V，用于NH3合成，*NNH的形成是通过RDS通过交替路径。CO2和N2的吸附能差分析与析氢反应（HER）相比，表明基于Cu2的C2N在13种分析的催化剂中表现出最高的CO2RR和NRR选择性。这项研究的结果为Cu基氮碳电催化剂的设计原理提供了创新的见解，用于产生高效的C-N偶联产物。
