Zn-Vacancy Engineered S-Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H2 Evolution

Vacancy defects engineering is a valid strategy to enhance the separation efficiency of photo-generated charges. Herein, a zinc vacancy mediated S-scheme ZnCdS/ZnS composite derived from ZnCdS/MOF-5 was constructed in-situ through the sacrificial reagent of Na2S/Na2SO3 aqueous solution in visible-light irradiation. The MOF-5 converted to ZnS (ZnS-V-Zn) with abundant zinc vacancies which were proved by the XPS and PL results. ZnS-V-Zn has two-photon absorption performance, which immensely enhanced the visible light absorption capacity for the photocatalysts. The photo-generated electrons of ZnS-V-Zn on the Zn-vacancy defect would regroup with the holes in the valence band (VB) of ZnCdS via ohmic contact which is induced by Zn-vacancy defects. Therefore, the photoexciton of ZnCdS can be able to separate effectively and eliminate the useless electrons and holes. The ZnCdS/ZnS(20) sample revealed an outstanding photocatalytic hydrogen generation rate of 12.31 mmol h(-1)g(-1) with a turnover number (TON) of 64.61, which is about 82.06 and 21.98 times greater than that of neat ZnS-V-Zn and ZnCdS. This work gives an insight into the design of the zinc vacancy-engineered S-scheme photocatalyst of ZnCdS/ZnS for highly efficient photocatalysis.

Automated summary

Vacancy defects engineering is an effective strategy to enhance the separation efficiency of photo-generated charges. The zinc vacancy mediated S-scheme ZnCdS/ZnS composite exhibits enhanced visible light absorption capacity and outstanding photocatalytic performance for hydrogen generation.