Doping of fluorine into SrTiO3 by spray pyrolysis for H2 evolution under visible light irradiation

Fluorine doped SrTiO3 photocatalysts were prepared by spray pyrolysis with varying fluorine content, and were employed for the first time for hydrogen evolution from aqueous methanol solution under visible light irradiation. The doped fluorine ions were substituted for 6-coordinated oxygen ions in the lattice of SrTiO3, which led to the generation of extra electrons and oxygen deficiencies. The doping of fluorine resulted in the partial transformation of the band gap structure of SrTiO3 to Sr(Ti4+1−xTi3+x)O3−xFx, by reducing Ti4+ to Ti3+ to compensate for the charge balance in the host lattice. The doping of fluorine contributed to the photocatalytic activity for hydrogen evolution by forming an acceptor level by Ti3+ from the conduction band to the valence band, generating the free electrons in the lattice structure, discarding the hydroxyl group on the surface and increasing the BET surface area and pore volume of the photocatalyst. The hydrogen evolution rate exhibited a maximum value of 464.1 μmol g−1 h−1 (QE=0.74%) with induction period of 1 h, when the amount of fluorine content doped into SrTiO3 was 4.0 mol%.

► Fluorine doped SrTiO3 was prepared by spray pyrolysis for the first time. ► Fluorine doped SrTiO3 photocatalysts were employed for hydrogen evolution. ► The fluorine resulted in the partial transformation of the band gap structure. ► The fluorine contributed to discard the hydroxyl group on the surface. ► The fluorine contributed to increase the BET surface area and pore volume.