Efficient visible light-driven photocatalytic CO₂ reduction by self-assembled CsPbBr₃ perovskite quantum dots on two-dimensional Bi₂O₂CO₃ petals

All-inorganic halide perovskites, such as CsPbBr₃ (CPB), face inherent limitations in the photocatalytic reduction of CO₂ due to their accelerated radiative recombination and insufficient charge carrier separation. In this work, a heterogeneous photocatalyst comprising Bi₂O₂CO₃ (BOC) petals and CPB quantum dots (QDs) was prepared. The opposite surface potentials of the BOC and CPB QDs enabled their electrostatic self-assembly. The CPB QD/BOC exhibited staggered energy-band configurations with a built-in internal electric field, leading to electron migration from the CPB QD to the BOC petals. Owing to its unique band structure and internal electric field, the CPB QD/BOC exhibited an S-scheme-type heterojunction, resulting in fast charge separation. As a result, the CPB QD/BOC exhibited a significantly enhanced photocatalytic CO₂ conversion rate to CO (80.5 μmol g^–1 h^–1) compared to pristine CPB QD (43 μmol g^–1 h^–1). This study opens new avenues for designing highly efficient photocatalysts using inorganic halide perovskites.