Sulfur-defective ZnIn2S4 nanosheets decorated by TiO2 nanosheets with exposed {001} facets to accelerate charge transfer for efficient photocatalytic hydrogen evolution

Abstract

Efficient separation and transfer of photogenerated carriers is one of the important factors for improving photocatalytic H₂ production from water splitting. In this work, ZnIn₂S₄ nanosheets (NSs) with sulfur defect (Vs-ZIS) and TiO₂ NSs with exposed {001} facets (001-TiO₂ NSs) are fabricated firstly, then the novel 001-TiO₂/Vs-ZIS heterojunction is constructed by employing NH₄HCO₃ as a binder, in which NH₄⁺ attracts the 001-TiO₂ and Vs-ZIS NSs to contact with each other and forms a compact 2D/2D heterostructure. Benefit from the suitable band structure of Vs-ZIS and 001-TiO₂, the photoinduced electrons on 001-TiO₂ recombine with the photoinduced holes on Vs-ZIS following Z-scheme mechanism, leading to the remarkable separation of photogenerated carriers. In addition, the synergistic effects of unique 2D/2D structure, highly active {001} facets and sulfur defect also contribute to the efficient separation of photogenerated carriers and enhanced photocatalytic activity in 001-TiO₂/Vs-ZIS system. The obtained 2D/2D 001-TiO₂/Vs-ZIS photocatalyst exhibits an outstanding H₂ evolution rate of 17113 μmol g⁻¹ h⁻¹, which is approximately 1426- and 3-fold compared to those of 001-TiO₂ NSs and Vs-ZIS NSs, respectively.