Co-doping schemes to enhance H2 evolution under visible light irradiation over SrTiO3:Ni/M (M = La or Ta) prepared by spray pyrolysis

Two photocatalysts, SrTiO3:Ni/La and SrTiO3:Ni/Ta, were prepared by continuous spray pyrolysis. The effects of the co-dopants on hydrogen evolution over the uncalcined photocatalysts were evaluated under visible light irradiation. The co-doping of La3+ into SrTiO3:Ni transformed the charge structure and increased the presence of Ni2+ at the expense of Ni3+ in the host lattice structure. The co-doping of Ta5+ into SrTiO3:Ni also increased the Ni2+/Ni3+ ratio around the Ti4+ ions. Compared with SrTiO3:Ni, SrTiO3:Ni/La showed a 3 times greater rate of hydrogen evolution under visible light irradiation and SrTiO3:Ni/Ta, a 4 times greater rate. The co-doping levels required for optimized hydrogen evolution over SrTiO3:Ni/La and SrTiO3:Ni/Ta prepared by spray pyrolysis were smaller than those prepared by other methods. Spray pyrolysis also produced particles with large surface areas and high roughnesses. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.