Effect of tri-doping on H2 evolution under visible light irradiation on SrTiO3:Ni/Ta/La prepared by spray pyrolysis from polymeric precursor

Tri-doped photocatalyst, SrTiO3:Ni/Ta/La, was prepared by spray pyrolysis from aqueous and polymeric precursor solutions. The third dopant, La3+, contributed to the BET surface area and porous morphology by preventing crystal growth, and increased the Ni2+/Ni3+ ratio by affecting the electron configuration in the lattice structure, which is closely related to the hydrogen evolution rate. The hydrogen evolution rate of the tri-doped photocatalyst, SrTiO3:Ni(0.2 mol%)/Ta(0.4 mol%)/La(0.3 mol%), was increased by about 60%–895.2 μmol g−1 h−1 from the value of 561.2 μmol g−1 h−1 for the co-doped photocatalyst, SrTiO3:Ni(0.2 mol%)/Ta(0.4 mol%), and was further enhanced to 2305.7 μmol g−1 h−1 when a polymeric precursor was used instead of an aqueous precursor in spray pyrolysis. The optimum additive content for polymeric precursor solution was 300 mol%.