Boosting CO ₂ Photoreduction through Interfacial Charge Transfer in a PCN/CsPbBr ₃ Quantum Dots Heterojunction

Utilizing solar energy to achieve photocatalytic CO2 reduction represents a potential method for CO2 conversion. As an emerging semiconductor material, metal halide perovskites offer advantages such as a broad light absorption range, long carrier lifetime, and tunable energy band, demonstrating good application prospects in the field of photocatalysis. CsPbBr3 (CPB) is a representative metal halide perovskite, possessing stable active sites and excellent photocatalytic activity. However, CPB tends to suffer from structural instability in certain environments, and its high carrier recombination rate leads to inadequate photocatalytic performance. To address these issues, we loaded CsPbBr3 quantum dots (CPB QDs) onto porous polygonal tubular carbon nitride (PCN) to construct a CPB-CN composite photocatalyst with a type-II heterojunction, which enables efficient photocatalytic CO2 reduction. Compared with pristine CPB QDs, the CPB-CN heterojunction significantly enhances carrier separation. By further optimizing the CPB-CN ratio, the optimal 20% CPB-CN composite photocatalyst exhibited improved photocatalytic reduction performance and charge separation efficiency. The CO2-to-CO reduction rate reached 20.94 μmol g–1 h–1, almost 3-fold of pure CPB. The improved photocatalytic properties can be ascribed to efficient electron extraction and migration at the interface of PCN and CPB QDs, the high specific surface area, and enhanced visible-light harvesting. This work demonstrates the potential for the design of highly catalytically active perovskite-based systems.