Characterization and photocatalytic activity of Fe- and N-co-deposited TiO 2 and first-principles study for electronic structure

Abstract

Titanium dioxide (TiO 2), co-deposited with Fe and N, is first implanted with Fe by a metal plasma ion implantation (MPII) process and then annealed in N 2 atmosphere at a temperature regime of 400–600 °C. First-principle calculations show that the (Fe, N) co-deposited TiO 2 films produced additional band gap levels at the bottom of the conduction band (CB) and on the top of the valence band (VB). The (Fe, N) co-deposited TiO 2 films were effective in both prohibiting electron–hole recombination and generating additional Fe–O and N–Ti–O impurity levels for the TiO 2 band gap. The (Fe, N) co-deposited TiO 2 has a narrower band gap of 1.97 eV than Fe-implanted TiO 2 (3.14 eV) and N-doped TiO 2 (2.16 eV). A significant reduction of TiO 2 band gap energy from 3.22 to 1.97 eV was achieved, which resulted in the extension of photocatalytic activity of TiO 2 from UV to Vis regime. The photocatalytic activity and removal rate were approximately two-fold higher than that of the Fe-implanted TiO 2 under visible light irradiation.