Enhanced Photocatalytic Hydrogen Evolution of In₂S₃ by Decorating In₂O₃ with Rich Oxygen Vacancies

The hydrogen (H₂) evolution rates of photocatalysts suffer from weak oxidation and reduction ability and low photogenerated charge carrier separation efficiency. Herein, by combining band-gap structure optimization and vacancy modulation through a one-step hydrothermal method, In₂O₃ containing oxygen vacancy (O_v/In₂O₃) is simply introduced into In₂S₃ to promote photocatalytic hydrogen evolution. Specifically, the change in the sulfur source ratio can induce the coexistence of O_v/In₂O₃ and In₂S₃ in a high-temperature hydrothermal process. Under light irradiation, In₂S₃@O_v/In₂O₃-0.1 nanosheets hold a remarkable average H₂ evolution rate up to 4.04 mmol g^-1 h^-1, which is 32.14, 11.91, and 2.25-fold better than those of pristine In₂S₃, In₂S₃@O_v/In₂O₃-0.02, and In₂S₃@O_v/In₂O₃-0.25 nanosheets, respectively. The ultraviolet-visible (UV-vis) diffuse reflectance and photoluminescence (PL) spectra reveal that the formation of O_v/In₂O₃ in In₂S₃ optimizes the band-gap structure and accelerates the migration of the photogenerated charge carrier of In₂S₃@O_v/In₂O₃-x nanosheets, respectively. Both the enhancement of oxidation and reduction ability and photogenerated charge carrier separation ability are responsible for the remarkable improvement in photocatalytic H₂ evolution performance. This work provides a new strategy to prepare a composite of metal sulfide and metal oxide through a one-step hydrothermal method.