Zn-In-O electrocatalysts with co-existing ZnO and In2O3 phases for efficient reduction of CO2 to formate through sacrificial mechanism

Electrochemical CO2 reduction reaction (eCO2RR) is considered an efficient approach to produce value-added chemicals and fuels. In this paper, a series of MOF-derived composite catalysts with coexisting In2O3 and ZnO are fabricated using a simple process for eCO2RR to produce formate. The Zn-In-O/800 catalyst achieves a formate Faradaic efficiency (FEHCOO−) of 94.25 % at −1.16 V vs. RHE, which can maintain over 89 % after 30 h in a stability test. The electrochemical evidence and density functional theory analysis show that the strong interface effect between In2O3 and ZnO can enhance the CO2 adsorption and activation, and promote the conversion of CO2 to formate. In addition, the ZnO phase can protect In2O3, as the main active site, from being reduced to a certain extent for a long time under negative potential, which ensures the high stability of the composite catalyst.