Copper-indium hydroxides derived electrocatalysts with tunable compositions for electrochemical CO₂ reduction

Bimetallic Cu-In hybrid electrocatalysts are promising noble metal-free catalysts for selective electrochemical CO₂ reduction reaction (ECO₂RR). Most reports show Cu-In catalysts are selective towards CO evolution. However, few show similarly high selectivity towards formate. Herein we fabricated composition tunable Cu-In hydroxides (Cu_xIn_y-OH) by the hydrothermal method and studied their composition effect on electrochemical CO₂ reduction in detail. We found that the selectivity of CO₂ reduction products shifted from CO to formate when the content of In increased in the Cu_xIn_y-OH electrocatalysts. The Cu rich electrocatalyst mostly produced CO, which could achieve a Faradaic efficiency (FE) to 75.8% at −0.59 V vs. RHE (Cu₇₆In₂₄ based electrocatalysts). In comparison, the In rich electrocatalysts selectively produced formate, which possessed the FE of formate up to 85% at −1.01 V vs. RHE. Our work systematically illustrates the composition effect on hybrid catalysts, and provides insights into the design of highly selective catalysts for ECO₂RR.