Surface local polarization induced by bismuth-oxygen vacancy pairs tuning non-covalent interaction for CO₂ photoreduction

Abstract

The inefficient charge separation and lack of active sites have been regarded as the main obstacles limiting the CO2 photoreduction efficiency. It is highly desirable but challenging to create a local polarization field to accelerate charge separation and build reactive sites for CO2 reduction dynamics. Herein, atomic level bismuth-oxygen vacancy pairs are engineered into Bi24O31Br10 (BOB) atomic layers to create a local polarization field. It facilitates photogenerated electrons to migrate from BOB to vacancy pair sites and favors the activation of CO2 molecules. Simultaneously, it works as reactive sites to tune the non-covalent interaction of intermediates and optimizes the reaction process. The vacancy pairs tuned surface atomic structures enable the formation of a highly stable Bi−C−O−Bi intermediate state and consecutive Bi−C−O intermediate, thus changing the rate-determining step from CO* formation to COOH* formation. Benefiting from these features, the VBiO-BOB delivers a 20.9-fold CO2 photoreduction activity enhancement relative to highly crystalline BOB in pure water with highly stability. This work provides new insights for the design of a vacancy pair to create local polarization and tune the non-covalent interaction.