Modulating AgIn@In2O3 Core–Shell Catalysts for Amplified Electrochemical Reduction of CO2 to Formate

Abstract Electrochemical CO 2 reduction (ECO 2 RR) is a promising way to convert CO 2 into valuable products, while requiring highly active and selective electrocatalysts. Herein, we synthesize a series of AgIn/In 2 O 3 catalysts with AgIn bimetallic core and In 2 O 3 shell structure for ECO 2 RR to produce formate. The AgIn bimetallic core improved the conductivity of the catalysts and the In 2 O 3 shell was reduced to In that served as active sites during the electrochemical reduction process. The activity and selectivity of formate production is related to the indium content in the AgIn/In 2 O 3 catalyst. The optimized Ag 50 In 50 @In 2 O 3 catalyst exhibited a high faradaic efficiency of 83 % at −0.9 V and −1.0 V vs. RHE for formate and the corresponding H 2 selectivity was largely suppressed to below 10 % of the applied potentials. There was no significant decay in current density and faraday efficiency of formate after 12 hours of stability testing. Density functional theory calculations indicated that the adsorption energy of *OCHO intermediate on the In shell was reduced due to the Ag−In interface interaction and enhanced charge transfer compared with pure In surface, which lead to the increased selectivity of formate.