Harnessing microenvironment of S-scheme heterostructure with dot-on-surface morphology and sulfur vacancies for efficient photocatalytic hydrogen evolution and tetracycline degradation

Reasonable fabrication of S-scheme heterojunction presents a positive outlook to boost photocatalytic hydrogen (H₂) production and degradation of antibiotics, while facing enormous challenges like rapid charge separation and catalytic reaction microdomain regulation. Herein, we deliberately anchor ultra-small nanodots V_S-ZnS_P with sulfur vacancies (V_S) derived from Zn-metal-organic framework (MOF) onto ZnIn₂S₄ (ZIS) nanosheets to rationally construct an S-scheme heterostructure ZIS/V_S-ZnS_P, achieving markedly enhanced photocatalytic H₂ evolution and tetracycline (TC) removal activity, with a high photo-removal TC efficiency of 98.92% within 60 min and an optimal photocatalytic H₂-generation rate of 5.31 mmol·g⁻¹·h⁻¹. The existence of V_S on V_S-ZnS_P, and the constructed dot-on-surface morphology of ZIS/V_S-ZnS_P are corroborated. The presence of V_S enhances the built-in interface electric field owing to the widened Fermi level gap of the S-scheme heterojunction, thereby accelerating the separation of photo-generated electrons and holes. Further, dot-on-surface morphology not only optimizes adsorption and desorption behavior of H*, but also improves adsorption capacity of O₂ and promotes formation of ·O₂⁻ by photo-generated electron reduction, simultaneously expediting photocatalytic H₂ evolution and TC removal. This dual microenvironment modulation strategy offers a viable scenario for conscious induction of rapid transfer of interface charges and regulation of catalytic reaction microdomain, significantly reinforcing photoredox efficiency.