Selective CO2 Electroreduction to Formate on Polypyrrole‐Modified Oxygen Vacancy‐Rich Bi2O3 Nanosheet Precatalysts by Local Microenvironment Modulation

Abstract Challenges remain in the development of highly efficient catalysts for selective electrochemical transformation of carbon dioxide (CO 2 ) to high‐valued hydrocarbons. In this study, oxygen vacancy‐rich Bi 2 O 3 nanosheets coated with polypyrrole (Bi 2 O 3 @PPy NSs) are designed and synthesized, as precatalysts for selective electrocatalytic CO 2 reduction to formate. Systematic material characterization demonstrated that Bi 2 O 3 @PPy precatalyst can evolve intoBi 2 O 2 CO 3 @PPy nanosheets with rich oxygen vacancies (Bi 2 O 2 CO 3 @PPy NSs) via electrolyte‐mediated conversion and function as the real active catalyst for CO 2 reduction reaction electrocatalysis. Coating catalyst with a PPy shell can modulate the interfacial microenvironment of active sites, which work in coordination with rich oxygen vacancies in Bi 2 O 2 CO 3 and efficiently mediate directional selective CO 2 reduction toward formate formation. With the fine‐tuning of interfacial microenvironment, the optimized Bi 2 O 3 @PPy‐2 NSs derived Bi 2 O 2 CO 3 @PPy‐2 NSs exhibit a maximum Faradaic efficiency of 95.8% at −0.8 V (versus. reversible hydrogen electrode) for formate production. This work might shed some light on designing advanced catalysts toward selective electrocatalytic CO 2 reduction through local microenvironment engineering.