Interfacial engineering of Z-scheme CsPbBr3/BiOCl heterojunction via solvothermal ion exchange for enhanced CO2 photoreduction

Abstract

Designing intimate heterojunction photocatalysts is key to achieving spatial charge separation and enhancing photocatalytic performance. However, from a kinetic perspective, poor interfacial interactions within heterojunctions often hinder charge transfer, limiting overall system efficiency. Herein, an intimate Z-scheme CsPbBr₃/BiOCl heterojunction was assembled through interfacial engineering via a facile solvothermal ion exchange method. Comprehensive DFT simulations and experimental characterizations reveal that the heterojunction forms through partial ion exchange between Br⁻ from CsPbBr₃ and Cl⁻ in BiOCl, along with removal of surface-preserved ligands from CsPbBr₃ at the interface. This leads to strong interfacial interaction, modulation of the optoelectronic properties, and enhanced charge transfer, as evidenced by photoelectrochemical measurements, photoluminescence, and time-resolved techniques. Further theoretical investigations demonstrated that incorporating Cl⁻ into CsPbBr₃ lowers the energy barriers in the rate-determining step for CO₂ reduction. As a paradigm, the CsPbBr₃/BiOCl heterojunction exhibits remarkable photocatalytic CO and CH₄ production compared to its individual and physically-assembled counterparts. This finding offers a promising approach for interface engineering of semiconductor heterojunctions to improve charge separation toward enhanced solar-fuel production.