H2 evolution under visible light irradiation on La and Cr co-doped NaTaO3 prepared by spray pyrolysis from polymeric precursor

Photocatalysts of Na_1−xLa_xTa_1−xCr_xO₃ and NaTa_1−xCr_xO₃ were prepared by spray pyrolysis from aqueous and polymeric precursor solution. Apart from the contribution of La³⁺ ions co-doped into NaTa_1−xCr_xO₃ on the BET surface area and the surface morphology by preventing crystal growth, this co-doping contributed to the increased Cr³⁺ concentration by partially tuning the electron configuration from A⁺B⁵⁺O₃ to (A⁺A′³⁺)²⁺(B⁵⁺B′³⁺)⁴⁺O₃ in the lattice of the photocatalyst. Na_1−xLa_xTa_1−xCr_xO₃ prepared from polymeric precursor solution reduced the induction period to 33% and enhanced the hydrogen evolution rate 5.6-fold to 1467.5 μmol g⁻¹ h⁻¹ compared with the equivalent values of NaTa_1−xCr_xO₃ prepared from aqueous precursor. The optimum amounts of dopant and additives comprising the polymeric precursor to maximize the hydrogen evolution rate were x = 0.003 and 300 mol%, respectively.