东南大学王金兰团队报道了表面含氧物质促进电催化CO₂还原的机理。相关研究成果发表在2024年3月5日出版的《科学通报》。

含氧物种已被证明在促进电催化CO₂还原（CO₂RR）中发挥关键作用，特别是在提高对多碳（C₂₊）产物的选择性方面。然而，潜在的促进机制仍存在争议，这大大限制了CO₂RR催化性能的合理优化。

该文以CO₂和O₂在Cu上的共电解为原始模型，通过综合的理论模拟，成功地从一个新的角度阐明了O₂如何促进CO₂RR。结果表明，在还原条件下，原料气中的O₂可以迅速还原为*OH，导致Cu表面的部分氧化。由于*OH和K+离子之间的静电相互作用，表面*OH加速了准特异性吸附K⁺的形成，这显著增加了Cu表面附近K⁺的浓度。

这些准特异性吸附的K⁺离子不仅可以降低C–C耦合势垒，而且可以促进CO₂的加氢以提高CO的产率，这是显著提高C2+产物效率的原因。在整个过程中，O₂共电解在稳定表面*OH方面发挥着不可或缺的作用。该机制也可用于理解电解质的高pH值和氧化物衍生的Cu（OD-Cu）中的残余O对C2++产物的催化效率的影响。

因此，该工作为改善铜基催化剂上的C2+产物的策略提供了新的见解，即在还原条件下保持表面的部分氧化。

附：英文原文

Title: Mechanism of surface oxygen-containing species promoted electrocatalytic CO2 reduction

Author: Zhanzhao Fu, Yixin Ouyang, Mingliang Wu, Chongyi Ling, Jinlan Wang

Issue&Volume: 2024/03/05

Abstract: Oxygen-containing species have been demonstrated to play a key role in facilitating electrocatalytic CO2 reduction (CO2RR), particularly in enhancing the selectivity towards multi-carbon (C2+) products. However, the underlying promotion mechanism is still under debate, which greatly limits the rational optimization of the catalytic performance of CO2RR. Herein, taking CO2 and O2 co-electrolysis over Cu as the prototype, we successfully clarified how O2 boosts CO2RR from a new perspective by employing comprehensive theoretical simulations. Our results demonstrated that O2 in feed gas can be rapidly reduced into *OH, leading to the partial oxidation of Cu surface under reduction conditions. Surface *OH accelerates the formation of quasi-specifically adsorbed K+ due to the electrostatic interaction between *OH and K+ ions, which significantly increases the concentration of K+ near the Cu surface. These quasi-specifically adsorbed K+ ions can not only lower the C–C coupling barriers but also promote the hydrogenation of CO2 to improve the CO yield rate, which are responsible for the remarkably enhanced efficiency of C2+ products. During the whole process, O2 co-electrolysis plays an indispensable role in stabilizing surface *OH. This mechanism can be also adopted to understand the effect of high pH of electrolyte and residual O in oxide-derived Cu (OD-Cu) on the catalytic efficiency towards C2+ products. Therefore, our work provides new insights into strategies for improving C2+ products on the Cu-based catalysts, i.e., maintaining partial oxidation of surface under reduction conditions.

DOI: 10.1016/j.scib.2024.03.012

Source: https://www.sciencedirect.com/science/article/abs/pii/S2095927324001567