Cr dopants and S vacancies in ZnS to trigger efficient photocatalytic H 2 evolution and CO 2 reduction

Driven by endless solar energy, photocatalytic H 2 evolution from water splitting and CO 2 conversion to hydrocarbon fuels over semiconductor photocatalysts are of great potential to simultaneously settle the greenhouse effect and energy shortage. Herein, Cr-doped zinc sulfide (ZnS) with accompanying sulphur vacancies (Vs) photocatalytic materials is developed by a facile hydrothermal method. The Cr dopants centralize photoinduced holes and Vs trap electrons, forming a synergistic effect for accelerating charge separation and transfer. The reaction energy barrier for both H 2 evolution and CO 2 reduction has been optimized. Therefore, in the absence of a cocatalyst, the optimal catalyst (Zn 0.94 Cr 0.06 S) achieves an outstanding H 2 evolution activity of 20.3 mmol g -1 h -1 , which is approximately 2.9 times higher than 6.9 mmol g -1 h -1 for pristine ZnS. In addition, in the gas-solid reaction system without co-catalysts or sacrificial agents, the Zn 0.94 Cr 0.06 S exhibits a considerable CO evolution rate of 19.56 mu mol g -1 h -1 , about 10.1 times higher than ZnS (1.94 mu mol g -1 h -1 ). Both the performances for H 2 evolution and CO 2 reduction of Zn 0.94 Cr 0.06 S outperform most of the previously reported photocatalysts. Particularly, the Zn 0.94 Cr 0.06 S possesses superior stability, the photoactivity of which exhibits no noticeable deactivation after six cycles' reactions. This work may shed light on the rational design and fabrication of highly efficient materials via combining individual element doping and defect engineering. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.