Fabrication of Hexagonal Prism-Shaped Double S-Scheme Cu₂O@CdS/ZnS Heterojunctions Utilizing Zeolite Templates: Enhanced Photocatalytic Hydrogen Production and Mechanism Insight

The production of photocatalytic hydrogen through water splitting is a promising green route due to its nontoxicity and harmlessness, but a key challenge lies in improving the separation efficiency of photogenerated charge carriers. To address this issue, we have successfully synthesized a hexagonal prism-shaped double S-scheme Cu₂O@CdS/ZnS heterojunction, utilizing a microporous zeolite as a sacrificial template. This unique structure exhibits a remarkable enhancement in charge carrier separation and transfer capabilities, enabling highly efficient photocatalysis. Specifically, the best photocurrent responses were observed in the 420-450 nm wavelength range. Notably, the hexagonal prism-shaped double S-scheme Cu₂O@CdS/ZnS heterojunction exhibits an excellent photocatalytic hydrogen production performance (8.30 mmol·h^-1·g^-1), which is nearly 10 times higher than that of pure CdS and 1.2 times higher than that of CdS/ZnS. To further elucidate the mechanism behind this enhanced hydrogen production, we propose a hydrogen production pathway for Cu₂O@CdS/ZnS, supported by density functional theory (DFT) calculations. The improved performance of hydrogen production can be attributed to the synergistic effect of the double S-scheme heterojunctions and the hexagonal prism-shaped structure, which collectively accelerate the photogenerated charge transport efficiency and enhance the hydrogen production efficiency.