CuAg bimetallic catalysts derived from an Ag-anchored Cu-based metal-organic framework for CO2 electroreduction to ethanol

Constructing a bimetallic tandem catalytic system is an effective strategy to promote the CO2 electroreduction (CO2ER) to ethanol. However, it is still difficult to achieve high selectivity for ethanol in the CO2ER because most of bimetallic catalysts lack sufficient biphasic boundaries. Herein, a series of novel CuAg bimetallic catalysts (CuAgx@NC) were prepared by anchoring Ag in the Cu-based metal-organic framework (NH2-Cu-BDC) followed with high-temperature pyrolysis. The results showed that the Ag in the optimal CuAg5@NC catalyst was highly dispersed and anchored on the Cu surface, so the catalyst had sufficient Cu-Ag biphasic boundaries, which resulted in superior C2 products (especially ethanol) selectivities in the CO2ER: the Faradaic efficiency (FE) for ethanol production reached 51.8 % at -1.0 V, and the FE for total C2 products reached 82.6 % at -1.2 V, which were higher than those of most previously reported CuAg electrocatalysts. Analyses of the reaction mechanism showed that the appropriate amount of Ag in the NH2-Cu-BDC derivative improved the CO coverage on the catalyst surface, promoted C-C coupling and enhanced the adsorption of key intermediates (such as CH3CHO) in the ethanol pathway.