A MOF-Derived Z-Scheme BiOCl/Bi ₂ O ₃ Heterojunction Photocatalyst with Enhanced Oxygen Vacancies for CO ₂ Reduction

The continuous rise in global fossil fuel consumption has led to increasing atmospheric CO2 levels and energy shortages. Photocatalytic CO2 reduction represents a promising strategy to address these challenges. In this study, a BiOCl/Bi2O3 Z-scheme heterojunction photocatalyst was successfully prepared by in situ fabrication of BiOCl on Bi2O3 derived from a bismuth-based metal–organic framework (CAU-17). By precisely tailoring the HCl concentration and impregnation time, we obtained a unique architecture of nanoplates encapsulated within hollow rods, which offers abundant active sites for catalytic reactions. Without using any cocatalyst, the BiOCl/Bi2O3 achieved a CO production rate of 107.8 μmol/g/h under 300 W Xe-lamp irradiation. The interfacial heterojunction in BiOCl/Bi2O3 provided an additional driving force for facilitating charge separation and transfer. Furthermore, the composite possessed a significantly increased concentration of oxygen vacancies, which not only promoted CO2 adsorption but also served as electron traps to suppress charge recombination. This study offers valuable insights into the rational design of efficient bismuth-based heterojunction photocatalysts for CO2 conversion.