Engineering Oxygen Vacancy in Support to Promote Activity of In 2 O 3 Catalyst for CO 2 Electroreduction to Formate

Abstract The electrocatalytic CO 2 reduction reaction (CO 2 RR) to formate offers an economical and effective strategy for CO 2 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 In 2 O 3 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 In 2 O 3 loaded on CZ with the highest O V concentration (In 2 O 3 /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, In 2 O 3 /CZ‐r also maintains its excellent CO 2 RR performance under low CO 2 concentrations and a wide pH range. Further insights into the mechanism of CO 2 RR reveal that the O V contributes greatly to the dissociation of H 2 O and further promotes the hydrogenation of adsorbed CO 2 species. Consequently, the reaction energy barrier for formate production is reduced and CO 2 RR activity is improved significantly. This study provides significant insights into the development of efficient CO 2 RR catalysts through strategic engineering of O V in support materials, thereby enhancing catalytic performance through synergistic interactions.