Preparation of novel SrTiO3:Rh/Ta photocatalyst by spray pyrolysis and its activity for H2 evolution from aqueous methanol solution under visible light

SrTiO₃:Rh/Ta powder was prepared by spray pyrolysis from polymeric precursors containing citric acid and ethylene glycol. Co-doping Ta into SrTiO₃:Rh increased the presence of Rh³⁺ in the host material. The retention of balanced charges by the substitution of two Ti⁴⁺ ions in the host material by one ion each of Rh³⁺ and Ta⁵⁺ enhanced hydrogen evolution from aqueous methanol solution under visible light irradiation (λ > 415 nm) by 3.5 times (to 531 μmol h⁻¹) and reduced the induction period by 50% (to 1 h), when compared with SrTiO₃:Rh. Thorough mixing of the multi-component spray pyrolysis precursor solution resulted in highly dispersed Rh ions and porous photocatalyst particles, which showed enhanced hydrogen evolution rate.