Vacancy engineering mediated hollow structured ZnO/ZnS S-scheme heterojunction for highly efficient photocatalytic H2 production

Designing a step-scheme (S-scheme) heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H2 production activity. Herein, a hollow ZnO/ZnS S-scheme heterojunction with O and Zn vacancies (VO, Zn-ZnO/ZnS) is rationally constructed via ion-exchange and calcination treatments. In such a photocatalytic system, the hollow structure combined with the introduction of dual vacancies endows the adequate light absorption. Moreover, the O and Zn vacancies serve as the trapping sites for photo-induced electrons and holes, respectively, which are beneficial for promoting the photo-induced carrier separation. Meanwhile, the S-scheme charge transfer mechanism can not only improve the separation and transfer efficiencies of photo-induced carrier but also retain the strong redox capacity. As expected, the optimized VO, Zn-ZnO/ZnS heterojunction exhibits a superior photocatalytic H2 production rate of 160.91 mmol g–1 h–1, approximately 643.6 times and 214.5 times with respect to that obtained on pure ZnO and ZnS, respectively. Simultaneously, the experimental results and density functional theory calculations disclose that the photo-induced carrier transfer pathway follows the S‐scheme heterojunction mechanism and the introduction of O and Zn vacancies reduces the surface reaction barrier. This work provides an innovative strategy of vacancy engineering in S-scheme heterojunction for solar‐to‐fuel energy conversion.