Effects of Mo sources on Mo doped SrTiO3 powder prepared by spray pyrolysis for H2 evolution under visible light irradiation

SrTiO3 was doped with three types of molybdenum ions (Mo6+, Mo4+, and Mo2+) by spray pyrolysis. The molybdenum ions narrowed the band gap of SrTiO3 to allow hydrogen evolution under visible-light irradiation. The molybdenum-doped SrTiO3 photocatalyst prepared from MoO2 (0.4 mol%) exhibited hydrogen evolution up to a rate of 1410.3 μmol g−1 h−1 with an induction period of 1 h. The use of MoO2 resulted in SrTiO3 doping by Mo6+ and Mo4+ ions, which enhanced the hydrogen evolution by forming 4d-like states under the conduction band. The ionic structure of SrTiO3 doped with Mo4+ and Mo6+ could be expressed as Sr[Ti4+1−x−y(Mo4+xMo6+y)]O3 from the X-ray photoelectron spectra.