Vacancy Pair-Induced Charge Rebalancing with Surface and Interfacial Dual Polarization for CO2 Photoreduction

Poor charge kinetics greatly reduce the efficiency of photocatalytic CO2 reduction. Herein, a synchronous surface and interfacial dual polarization strategy was developed to promote charge separation. Bi–O vacancy pairs in Bi24O31Br10 atomic layers can trigger strong coupling between black phosphorus (BP) and Bi24O31Br10, forming a restructured closely contacted BP–Bi24O31Br10 configuration with a charge-redistributed interface via electronegativity-induced charge rebalancing. The Bi–O vacancy pairs on the surface of Bi24O31Br10 and restructured BP/Bi24O31Br10 interface enable synchronous surface and interfacial dual polarization, creating an electronic bridge from the interior of Bi24O31Br10 to the BP surface, as proven by ultrafast transient absorption spectroscopy. This configuration favors a low CO2 activation energy barrier, effectively stabilizes COOH* intermediates, and decreases the rate-determining step energy barrier. Benefiting from these features, the stable CO generation rate of optimized BP–Bi24O31Br10 reaches up to 39.8 μmol g–1 h–1 via CO2 photoreduction in water, which is 2.4 and 46.8 times higher than those of defective Bi24O31Br10 atomic layers and defect-poor Bi24O31Br10, respectively. This study provides insights into the synchronous design of surface defects and restructured interfaces for dual polarization.