Electroreduction of carbon dioxide to multi-electron reduction products using poly(ionic liquid)-based Cu-Pd catalyst

Electrocatalytic reduction of CO_(2)(CO_(2)RR)to multi-electron(>2e–)products provides a green and sustainable route for producing fuels and chemicals.Introducing the second metal element is a feasible strategy for"managing"the key intermediate on Cu-based materials to further improve the CO_(2)RR catalytic performance.In this work,palladium,which promises the generation of CO,was introduced into the poly(ionic liquid)-based copper hybrid(Cu@PIL)to construct a novel Cu-Pd bimetallic electrocatalyst(Cu@PIL@Pd).Remarkably,with a small dosage of palladium(2.0 mol%compared with Cu),a high faradaic efficiency(FE)for C_(2+)products(68.7%)was achieved at–1.01 V(with respect to the reversible hydrogen electrode(RHE),the same below)with a high partial current density of 178.3 mA cm^(-2).Meanwhile,high selectivity towards CH4(FE=42.5%)and corresponding partial current density of 172.8 mA cm^(-2)were obtained on the same catalyst at–1.24 V,signifying a significant potential-dependent selectivity.Mechanistic studies reveal that both copper and palladium oxides are reduced to metallic states during the CO_(2)RR.The presence of the adjoint copper phase and the highly dispersed electrostatic layer promote the generation of CO on the palladium components(both the PdO_(2)phase and the Pd(II)site).Besides,the local CO^(*)was enriched by the significant diffusion resistance of CO in the PIL layer.The spillover of CO^(*)from Pd sites to the adjoint Cu sites,accompanied by the increased local concentration of CO^(*)around Cu sites,accounted for the observed good CO_(2)RR catalytic performance,especially the high C_(2+)product selectivity.