Ag decorated-Cu2O catalysts with enhanced selectivity for CO2 electroreduction toward C2+ products

Abstract

Copper-based electrocatalysts have been widely used to generate C2+ products via the electrocatalytic carbon dioxide reduction reaction (CO2RR) because the catalysts possess unique properties for C-C coupling. Tandem catalysis is an attractive concept for C2+ production, enhancing selectivity and activity by combining CO-generating catalysts with Cu-based catalysts. Herein, the ability of Ag decoration to improve the selectivity of the Cu2O catalysts for C2+ production was investigated. The Ag/Cu2O catalyst with 10 wt% Ag content on the Cu2O surface (10 Ag/Cu2O) exhibited high Faradaic efficiency (FE) of 48% for C2+ products at –0.99 V (vs. RHE). Moreover, the partial current density of C2+ products on the 10 Ag/Cu2O was improved by 33% compared to the bare Cu2O catalyst. The intermediate (CO) generated on the Ag surface migrates by diffusion and/or sequential desorption-re-adsorption from Ag to Cu at the Ag-Cu interface of the Ag/Cu2O, increasing CO coverage on the Cu surface. The increase in CO coverage on the Cu surface of the Ag/Cu2O catalysts after decoration with Ag effectively reduces the hydrogen evolution reaction (HER), enhancing C-C coupling to generate C2+ products on the Ag/Cu2O. In addition, density functional theory (DFT) calculation results also revealed that Ag provides more CO2 activation sites, increasing CO coverage and reducing hydrogen adsorption energy, thus suppressing HER and improving the selectivity of CO2RR toward C2+ production.