Enhanced Photocatalytic Activity for CO₂ Reduction over a CsPbBr₃/CoAl-LDH Composite: Insight into the S-Scheme Charge Transfer Mechanism

The construction of an S-scheme heterojunction is recognized as a promising approach to developing efficient photocatalytic systems. Herein, a novel S-scheme heterojunction of CsPbBr3 nanocrystals/CoAl layered double hydroxide (LDH) nanosheets was fabricated and applied for photocatalytic conversion of CO2. CsPbBr3/CoAl-LDH composites exhibited superior activity for CO2 photoreduction under visible light. The composite containing 60 wt % CsPbBr3 displayed the optimal photocatalytic performance, which was enhanced by 2.6 and 9.9 times compared to CsPbBr3 and CoAl-LDH, respectively. Moreover, this composite also showed stable photocatalytic activity with no detectable decrease after four cycles. The formation of an S-scheme heterojunction can promote the electron–hole separation and provide a higher redox potential of the composite, thus leading to the remarkable photocatalytic performance toward CO2 reduction. This study provides a new perspective for designing and manufacturing perovskite-based S-scheme photocatalytic systems for CO2 reduction.