Constructing an S-scheme heterojunction of 2D/2D Cd0.5Zn0.5S/CuInS2 nanosheet with vacancies for photocatalytic hydrogen generation under visible light

Exploring efficient and stable water-splitting photocatalysts is critical for realizing conversion solar energy into hydrogen energy. Herein, a unique 2D/2D S-scheme Cd 0.5 Zn 0.5 S/CuInS 2 heterojunction with sulfur vacancies was rationally designed by chemically converting inorganic–organic hybrid ZnS(en) 0.5 into inorganic Cd 0.5 Zn 0.5 S nanosheets and fabricating with CuInS 2 at 350 °C under an N 2 atmosphere. The final Cd 0.5 Zn 0.5 S/CuInS 2 photocatalyst was composed of thin nanosheets with a substantial interfacial contact area, which enhanced light absorption and allowed directional charge transfer and separation. Under visible light irradiation, the photocatalytic H 2 evolution activities of Cd 0.5 Zn 0.5 S nanosheets is 0.79 mmol·g −1 ·h −1 , which is greater than other solid solution materials obtained by varying Cd and Zn ratios. The 2D/2D nanosheets with 8% CuInS 2 exhibit excellent hydrogen evolution activity with yields of 7.73 mmol·g −1 ·h −1 , which are 9.8 and 138 times higher than Cd 0.5 Zn 0.5 S and CuInS 2 . In addition, Cd 0.5 Zn 0.5 S/CuInS 2 photocatalyst demonstrates outstanding stability and activity over the course of 24-hour period. Moreover, the transfer pathway of photogenerated charges were explored by the energy band bending, which proved that an S-scheme heterojunction is synthesized successfully.This work offers a useful methodology for analyzing S-scheme heterojunction with abundant sulfur vacancies, and improving the solar hydrogen evolution performance of Cd 0.5 Zn 0.5 S photocatalyst.