Unraveling in-situ electrochemical reconstruction of indium oxide catalysts with oxygen vacancy for enhanced electrocatalytic CO2-to-Formate conversion

Indium-based materials have emerged as promising alternative catalysts for the selective electroreduction of CO2 to formate, yet the optimal catalytic configuration remains elusive. Herein, theoretical calculation reveals that metallic indium over oxygen vacancy-containing In2O3 support (In/In2O3-VO) possesses the lowest energy barriers (0.99 eV) for CO2 reduction to formate. A rational air-annealing strategy applied to In3+-adsorbed resin is developed to synthesize indium oxide catalysts containing oxygen vacancy (R-In2O3). In-situ spectroscopy techniques confirm in-situ electrochemical reconstruction of the In/In2O3 configuration and the effective stabilization of the key reaction intermediate (HCOO*). Consequently, the catalyst delivers excellent CO2-to-formate conversion performance, maintaining a current efficiency above 92% over 56 hours of galvanostatic electrolysis at 250 mA cm−2. These insights provide an effective strategy for the rational design of high‐performance and durable indium‐based electrocatalysts for sustainable formate production.