O, S-Dual-Vacancy Defects Mediated Efficient Charge Separation in ZnIn₂S₄/Black TiO₂ Heterojunction Hollow Spheres for Boosting Photocatalytic Hydrogen Production

Abstract

Defective ZnIn₂S₄ nanosheets/mesoporous black TiO₂ heterojunction hollow spheres (H-ZIS/b-TiO₂) are prepared through hydrothermal and surface low-temperature hydrogenation strategies, which show broad-spectrum response and excellent charge separation efficiency. This H-ZIS/b-TiO₂ flower-like heterojunction hollow spheres with a narrow band gap of ∼1.88 eV expand the light response to visible light and show excellent photocatalytic hydrogen evolution rate (278 μmol h^-1 50 mg^-1) under visible-light irradiation, which is 1.5 times as high as that of ZnIn₂S₄/black TiO₂ heterojunction hollow spheres (ZIS/b-TiO₂) (181 μmol h^-1 50 mg^-1). The excellent photocatalytic performance is due to the formation of O, S dual vacancies in b-TiO₂ and H-ZIS providing more active sites for photocatalytic reaction and improving the charge separation efficiency, heterojunctions promoting transport of photogenerated carriers, and the hollow structure increasing light utilization by reflecting light. The novel heterojunction hollow sphere with high performance has broad application prospects in the field of energy.