Indium oxide-based Z-scheme hollow core-shell heterostructure with rich sulfur-vacancy for highly efficient light-driven splitting of water to produce clean energy.

Crafting an inorganic semiconductor heterojunction with defect engineering and morphology modulation is a strategic approach to produce clean energy by the highly efficient light-driven splitting of water. In this paper, a novel Z-scheme sulfur-vacancy containing ZnInS (Vs-ZnInS) nanosheets/InO hollow hexagonal prisms heterostructrue (Vs-ZIS6INO) was firstly constructed by an oil bath method, in which Vs-ZnInS nanosheets grew on the surfaces of InO hollow hexagonal prisms to form a hollow core-shell structure. The obtained Vs-ZIS6INO heterostructrue exhibited much enhanced activity of the production of H and HO by the light-driven water splitting. In particular, under visible light irradiation (λ > 420 nm), the rate of generation of H of Vs-ZIS6INO sample containing 30 wt% Vs-ZnInS (30Vs-ZIS6INO) could reach 3721 μmol gh, which was 87 and 6 times higher than those of ZnInS (43 μmol gh) and Vs-ZnInS (586 μmol gh), respectively. Meanwhile, 30Vs-ZIS6INO could exhibit the rate of HO production of 483 μmol gh through the dual pathways of indirect 2e oxygen reduction (ORR) and water oxidation (WOR) without adding any sacrifice agents, far exceeding InO (7 μmol gh) and Vs-ZnInS (58 μmol gh). The excellent photocatalytic activities of H and HO generations of Vs-ZIS6INO sample might result from the synergistic effect of the sulfur vacancy, hollow core-shell structure, and Z-scheme heterostructure, which accelerated the electron delocalization, enhanced the absorption and conversion of solar energy, reduced the carrier diffusion distance, and ensured high REDOX ability. In addition, the possible photocatalytic mechanisms for the production of H and HO were discussed in detail. This study provided a new idea and reference for constructing the novel and efficient inorganic semiconductor heterostructures by coordinating vacancy defect and morphology design to adequately utilize water splitting for the production of clean energy.