Electrochemical CO2 Reduction over In Alloy Electrodes and Depth‐Profiled Interfacial Electronic Structures

Abstract Indium (In) in the p‐block of the periodic table has demonstrated a high Faradaic efficiency (FE) for formate production in electrochemical CO 2 reduction reaction (EC CO 2 RR). Therefore, In‐based alloys have been extensively employed to improve performance. However, the effects of alterations in surface elemental composition and interfacial electronic structure have not been investigated in detail. In this study, we introduced In and In‐based alloys (InGaAg, InSn, and InSnBi) electrodes for EC CO 2 RR. The experimental conditions employed in the demonstrated tests encompass various factors, such as applied potentials, electrolytes and their concentrations, as well as the effects of light, including UV and infrared light radiation. Nuclear magnetic resonance spectroscopy confirmed formate production with high FE (97.7 %) and selectivity (98.5 %). Minor amounts of CO, CH 4 , and H 2 were also detected by gas chromatography. Depth‐profiling X‐ray photoelectron spectroscopy was used to examine the effects of alloying, potential‐induced exposed surface elemental compositions, and interfacial electronic structures. The study found that the elemental distribution was substantially altered after EC CO 2 RR. These unique results provide valuable information for the improvement and theoretical modeling of In‐based alloy electrocatalysts for CO 2 recycling.