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

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 VsZIS 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 001TiO2/Vs-ZIS system. The obtained 2D/2D 001-TiO2/Vs-ZIS photocatalyst exhibits an outstanding H2 evolution rate of 17113 mu mol g-1 h-1, which is approximately 1426- and 3-fold compared to those of 001-TiO2 NSs and VsZIS NSs, respectively.