表面含氧物种对电催化CO_(2)还原的内在促进机制

Mechanism of surface oxygen-containing species promoted electrocatalytic CO_(2)reduction

Oxygen-containing species have been demonstrated to play a key role in facilitating electrocatalytic CO_(2) reduction(CO_(2)RR),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 CO_(2)RR.Herein,taking CO_(2) and O_(2) co-electrolysis over Cu as the prototype,we successfully clarified how O_(2) boosts CO_(2)RR from a new perspective by employing comprehensive theoretical simulations.Our results demonstrated that O_(2) 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 CO_(2) to improve the CO yield rate,which are responsible for the remarkably enhanced efficiency of C^(2+)products.During the whole process,O_(2) 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 C^(2+)products.Therefore,our work provides new insights into strategies for improving C^(2+)products on the Cu-based catalysts,i.e.,maintaining partial oxidation of surface under reduction conditions.