Plasma-assisted and oxygen vacancy-engineered In₂O₃ films for enhanced electrochemical reduction of CO₂

Oxygen vacancy-enriched In₂O₃ nanomaterials are promising catalysts for electrocatalytic CO₂ reduction owing to their excellent capability to activate CO₂ during catalysis. Despite substantial progress, facile and controllable methods for oxygen vacancy construction require further exploration. Herein, magnetron sputtering is used for generating oxygen vacancies in In₂O₃ films with the help of high-energy plasma treatment. A series of In₂O₃ films were prepared through magnetron sputtering at different oxygen partial pressures, and the In₂O₃ sample without oxygen partial pressure exhibited excellent performance in HCOOH production. The large yield of C₁ products is mainly attributed to the increased surface electronic density according to density functional theory (DFT) calculations. The DFT results indicated that the reaction proceeded with *COOH obtained as the intermediate, and the formation barrier of *COOH decreased with an increase in oxygen vacancies. The present route provided a novel and convenient strategy for developing defect-rich catalysts for electrochemical CO₂RR.