Effects of F for enhancement of H_2 evolution on visible-light-driven photocatalyst of SrTiO_3:Cr/Ta/F prepared by spray pyrolysis

摘要

Both anion (F~-) and cation (Cr~(3+)/Ta~(5+)) doping were conducted simultaneously to prepare tri-doped photocatalyst, SrTiO_3:Cr/Ta/F, by spray pyrolysis from aqueous precursor solutions. The ternary doping of F~- ion into SrTiO_3:Cr/Ta increased the hydrogen evolution rate up to 3887.9 μmol g~(-1) h~(-1) (quantum efficiency: 6.22%) under visible light irradiation, which was 1.84 times higher than that over SrTiO_3:Cr/Ta. The optimum contents of dopants for the maximum hydrogen evolution rate were Cr (0.1 mol%), Ta (0.1 mol%) and F (6.0 mol%), respectively. The ternary doping of F~-ion contributed to the reduction of Ti~(4+) and Cr~(6+) ions to Ti~(3+) and Cr~(3+) ions, respectively, by the generation of extra electrons in the lattice. The partially substituted structure of the photocatalyst could be expressed as Sr(Ti~(4+)_(1-2x-z)Ti~(3+)_zCr~(3+)_(x-y)Cr~(6+)_yTa~(5+)_x)(O~2 _(3-w)F_w).