Step-Scheme Photocatalyst of CsPbBr₃ Quantum Dots/BiOBr Nanosheets for Efficient CO₂ Photoreduction

Heterojunction manipulation has been deemed as a promising approach in exploring efficient photocatalysts for CO₂ reduction. In this article, a novel step-scheme (S-scheme) photocatalyst of CsPbBr₃ quantum dots/BiOBr nanosheets (CPB/BiOBr) was fabricated via a facile self-assembly process. The strong interaction, staggered energy band alignments, and much different Fermi levels between CsPbBr₃ and BiOBr promised the formation of an S-scheme heterojunction. The resultant CPB/BiOBr heterojunction delivered remarkable photocatalytic performance in CO₂ reduction, with an electron consumption rate of 72.3 μmol g^-1 h^-1, which was 4.1 and 5.7 times that of single CsPbBr₃ and BiOBr, respectively. The superior photocatalytic performance originated from the impactful spatial separation of photoinduced electron-hole pairs, as well as the preservation of strongly reductive electrons for CO₂ reduction. This work offers a rational strategy to design S-scheme heterojunctions based on lead halide perovskites, which are expected to have potential applications in the field of photocatalysis and solar energy utilization.