Optimal Architecture of a Dual S-Scheme ZnIn 2 S 4 -ZnO-Al 2 O 3 Heterosystem with High H 2 Evolution Rate under Visible Light.

In this study, dual S-scheme ZnIn 2 S 4 -Al 2 O 3 -ZnO (ZIS-Al-Zn) heterojunctions were produced by a facile, low cost, and rapid combustion technique. These heterojunctions accelerated the photocatalytic hydrogen production due to the multi-channel-promoted separation of photocarriers. By optimizing the content of the components, the synthesized ZIS-Al-Zn composite with 20 wt% of ZnIn 2 S 4 and 30 wt% of Al 2 O 3 in the ZIS-Al-Zn composite demonstrated the highest hydrogen production rate of 54.2 mmol g -1 h -1 , which was nearly 11 and 8.30 times better than ZnO-Al 2 O 3 and ZnO-ZnIn 2 S 4 composites, respectively. The results of DRS, PL, EIS, LSV, and CV techniques showed the highest shift in the light absorption, rapid interfacial transfer, and quenched recombination of photocarriers over the ternary ZIS-Al-Zn composite than single and binary catalysts. The obtained results revealed the formation of a dual S-scheme mechanism of transfer of photocarriers in ZIS-Al-Zn heterojunctions, contributing to better hydrogen production efficiency. The optimized ZIS-Al-Zn composite also exhibited good stability and reusability.