Benzyl alcohol promoted electrocatalytic reduction of carbon dioxide and C₂ production by Cu₂O/Cu

Oxide-derived copper (OD-Cu)-based materials containing Cu^δ+ (0 < δ ≤ 1) have been considered as promising electrocatalysts for electrochemical CO₂ reduction reaction (ECO₂RR) to produce valuable C₂ products, which, however, suffer from poor stability, mainly due to the inevitable reduction of Cu^δ+. We report here that the benzyl alcohol (BA) introduced in catholyte presents a markedly positive effect on the durability and C₂ selectivity enhancement of ECO₂RR when OD-Cu-based material is adopted as cathode electrocatalyst. The critical evidence of ECO₂RR intermediates has been provided by in situ Raman and FTIR spectroscopy, which reveals the surface mechanisms of BA-assisted ECO₂RR over OD-Cu catalysts. On the one hand, the introduction of BA increases the CO₂ supply for ECO₂RR by slowing down its neutralizing reaction, which results in the increased intermediate species coverage on the catalytic surface therefore the delayed self-reduction of Cu^δ+; On the other hand, the interaction between BA and the intermediate species *CO during ECO₂RR brings an enhanced selectivity of C₂ products (FE _C2 = 85.5 % at −1.38 V vs RHE). Besides, an energy-savings and economic electrolyzer can be achieved by coupling anodic BA oxidation reaction to benzoic acid and ECO₂RR to C₂ products with much lowered cell voltages.