Synergistic Effect of the Surface Vacancy Defects for Promoting Photocatalytic Stability and Activity of ZnS Nanoparticles

High activity, high stability, and low cost have always been the pursuit of photocatalyst design and development. Herein, a simple method is used to integrate abundant anion vacancies (V-S) and cation vacancies (V-Zn) on the surface of ZnS (M-ZnS), deriving V-S and V-Zn pairs (vacancy pairs), isolated Zn atoms (Zn-iso), and isolated S atoms (S-iso). Abundant surface vacancy defects fully expose and activate the surface atoms, regulate the band structure, and significantly improve the separation of photogenerated carriers. M-ZnS is endowed with high activity, and the average hydrogen production rate of the optimal sample increases to 576.07 mu mol.g(-1).h(-1) (lambda > 400 nm). Theoretical simulations indicate that the activated Zn atoms are the dominant active sites via the formation of a Zn-OH bond with H2O. Especially, the strong interactions of electrons in atomic orbitals at vacancy pairs and the introduction of V-Zn are conducive to high stability. The optimal sample maintains an average hydrogen production rate of 6.59 mmol.g(-1).h(-1) (300 W Xe lamp) after nine cycles. Hence, this work deepens the understanding of vacancy defects and provides an idea for the design of a stable photocatalyst.

Automated summary

Integration of abundant anion and cation vacancies on ZnS surface enhances the activity and stability of the photocatalyst, leading to an increased hydrogen production rate. Activated Zn atoms forming Zn-OH bonds are identified as the main active sites, while interactions in atomic orbitals at vacancy pairs and the introduction of V-Zn contribute to high stability. The optimal sample maintains a high hydrogen production rate after multiple cycles, demonstrating the potential for stable photocatalyst design.