Photocatalytic H2 evolution under visible light from aqueous methanol solution on NaBixTa1−xO3 prepared by spray pyrolysis

Solid–solution NaBi_xTa_1−xO₃ photocatalyst powders were prepared by spray pyrolysis from aqueous and polymeric precursor solutions. The effects of Bi ions and additives in the precursors on the photocatalytic activities of the resulting catalysts were investigated by measuring hydrogen evolution rate from aqueous methanol solution under visible light irradiation (λ > 415 nm). The effects of NiO co-catalyst on hydrogen evolution rate are also tested. Hydrogen evolution rate was enhanced almost 20 times (to 1355 μmol g⁻¹ h⁻¹), with an induction period of 1 h, compared with a photocatalyst prepared by hydrothermal method because of the compositional uniformity and unique surface morphology with large BET surface area of the photocatalyst. Bi ions in the photocatalyst were confirmed by XPS to be mainly present as Bi⁵⁺. Polymeric additives to the precursors and NiO co-catalyst resulted in maximized hydrogen evolution rate when used at 300 mol% and 0.2 wt.%, respectively. The composition of the photocatalyst was optimized at NaBi_0.07Ta_0.93O₃.