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 29.6 mA/cm² and 87% to 6.3 mA/cm² and 75%, respectively with time extending to 7200 s, at –1.0 V 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.