Unveiling the relationship between structural evaluation and catalytic performance of InOOH during electroreduction of CO2 to formate

The Electrochemical CO2 Reduction Reaction (ECO2RR) to formate is perceived as a technoeconomic pathway for transforming renewable electricity into fuels. However, the indeterminate mechanism underlying structural self-reconstruction obstructs the strategic design of a high-performance In catalyst for the ECO2RR. In this study, we chose InOOH as the model catalyst to illustrate the dynamic structure of In-based catalysts during reconstruction in the ECO2RR. The findings of the current study indicate that the in situ electrochemical reconstruction of crystalline InOOH results in the creation of crystalline In clusters/InOOH, followed by In/InOOH heterostructures, and finally, metallic In over time. The efficiencies of the different phases conformed to the sequence: In clusters/InOOH > In/InOOH heterostructures > metallic In. This progression leads to a continuous drop in maximum current density and Faradaic efficiency from 29.6mA/cm2 and 87% to 6.3mA/cm2 and 75%, respectively, with time extending to 7200s, at -1.0V relative to the reversible hydrogen electrode. Our in situ characterization and theoretical studies highlighted the crucial role of the In-cluster/InOOH interface in CO2 activation and conversion.