Photocatalytic activity of fluorine doped SrTiO3 under the irradiation of UV/solar light: Extended visible light absorption by the bulk lattice F− ions and suppression of photogenerated charge carrier recombination by the surface F− ions

Abstract

The SrTiO3 and F doped SrTiO3 samples retains cubic perovskite structure. XPS results confirmed the presence of F− ion on the surface and also in the bulk lattice. Energy levels like Ti3+- Vo states and oxygen vacancies (Vo) existing as neutral/singly ionized (F+ center)/doubly ionized (F center) states and the dopant energy levels are responsible for the visible light photocatalytic activity of the doped samples. Further the surface fluorine acts as an efficient electron trapping center due to the high electronegativity of F− ions and it also hinders the electron hole recombination. The existence of the above energy states are confirmed by the XPS and PL techniques. The enhanced photocatalytic activity is attributed to the synergistic effects of both surface and bulk fluorine ions in the SrTiO3 lattice.