Dual-functional Cs2CuBr4@ ZnO S-scheme heterojunction photocatalyst for efficient organic pollutant degradation and toluene oxidation.

Halide perovskites hold tremendous promise for photocatalytic applications, however, their performance is hindered by the rapid recombination of charge carriers. In this work, a facile in-situ confinement synthesis strategy is developed to enable the controlled growth of Cs2CuBr4 nanodots (NDs) within ZnO nanoboxes (NBs), thereby constructing a novel Cs2CuBr4@ZnO S-scheme heterojunction photocatalyst. This design alleviates the environmental drawbacks of conventional lead-based perovskites and enhances the efficiency of separating photogenerated charge carriers. Cs2CuBr4@ZnO exhibits outstanding performance in various photocatalytic functionalities, demonstrating high activity in azo dye degradation and remarkable efficiency in toluene oxidation, which achieves a catalytic rate of 5672 and 1287 μmol g-1 h-1 for benzaldehyde and benzyl alcohol. Comprehensive characterizations and band structure analysis reveal that the enhanced activity originates from the S-scheme charge transfer pathway, which simultaneously facilitates efficient charge separation and preserves strong redox ability. To clarify the adsorption characteristics and the crucial reaction steps during toluene photo-oxidation, we conducted density functional theory (DFT) calculations. Overall, this study introduces a versatile construction strategy for Lead-free halide perovskite-based heterojunctions and provides new design guidance and theoretical insight for their high-value applications in environmental remediation and selective organic transformations.