Engineering Oxygen Vacancy in Support to Promote Activity of In2O3 Catalyst for CO2 Electroreduction to Formate

The electrocatalytic CO₂ reduction reaction (CO₂RR) to formate offers an economical and effective strategy for CO₂ conversion and storage. Indium (In) based catalysts exhibit high activity and selectivity for formate production; however, their performance still requires enhancement to meet these goals. A novel approach is proposed by depositing In₂O₃ onto an oxygen vacancy (O_V)-enriched support, ceria-zirconia solid solutions (CZ), to activate synergistic effects. The O_V concentration in CZ support is effectively adjusted by controlling the Ce concentration. Electrochemical tests show that In₂O₃ loaded on CZ with the highest O_V concentration (In₂O₃/CZ-r), achieving an impressive current density (165 mA cm⁻²) and a Faradaic efficiency for formate of 95.3% at −1.27 V versus RHE. Notably, In₂O₃/CZ-r also maintains its excellent CO₂RR performance under low CO₂ concentrations and a wide pH range. Further insights into the mechanism of CO₂RR reveal that the O_V contributes greatly to the dissociation of H₂O and further promotes the hydrogenation of adsorbed CO₂ species. Consequently, the reaction energy barrier for formate production is reduced and CO₂RR activity is improved significantly. This study provides significant insights into the development of efficient CO₂RR catalysts through strategic engineering of O_V in support materials, thereby enhancing catalytic performance through synergistic interactions.