Enhancing hydrogen evolution of water splitting under solar spectra using Au/TiO2 heterojunction photocatalysts

Abstract

An effective improvement of hydrogen evolution from water splitting under solar light irradiation was investigated using quantum dots (QDs) compounds loaded onto a Au/TiO2 photocatalyst. First, Au/TiO2 was prepared by the deposition-precipitation method, and then sulfide QDs were loaded onto the as-prepared Au/TiO2 by a hydrothermal method. QDs were loaded onto Au/TiO2 to enhance the energy capture of visible light and near-infrared light of the solar spectrum. The results indicated that the as-prepared heterojunction photocatalysts absorbed the energy from the range of ultraviolet light to the near-infrared light region and effectively reduced the electron-hole pair recombination during the photocatalytic reaction. Using a hydrothermal temperature of 120 °C, the as-prepared (ZnS–PbS)/Au/TiO2 photocatalyst had a PbS QDs particle size of 5 nm, exhibited an energy gap of 0.92 eV, and demonstrated the best hydrogen production rate. Additionally, after adding 20 wt % methanol as a sacrificial reagent to photocatalyze for 5 h, the hydrogen production rate reached 5011 μmol g−1 h−1.