Impact of Tungsten, Iron and Molybdenum on the TiO 2 Geometrical Network and Optoelectronic Properties

Density functional theory(DFT) calculations were employed to examine the dopants effect on the electronic and optical properties of anatase TiO 2 . Tungsten(W), iron(Fe) and molybdenum(Mo) doped, co-doped and tri-doped systems were modeled. Comparison was made, based on TiO 2 anatase single doped (W–TiO 2 , Fe–TiO 2 , Mo–TiO 2 ), three different models of co-doped (WFe–TiO 2 ), (FeMo–TiO 2 ) and (MoW–TiO 2 ) and a tri-doped TiO 2 (WFeMo–TiO 2 ). Single-doped W–TiO 2 , Fe–TiO 2 and Mo–TiO 2 has reduced the band gap of pure anatase TiO 2 from 2.12Formula: see texteV to 2.0Formula: see texteV, 1.5Formula: see texteV and 1.80Formula: see texteV, respectively. While co-doped WFe–TiO 2 , FeMo–TiO 2 and MoW–TiO 2 has reduced the band gap to 0.75Formula: see texteV, 1.4Formula: see texteV and 1.6Formula: see texteV, respectively. Tri-doped WFeMo–TiO 2 has a band gap of 1.5Formula: see texteV. Single-doped Fe–TiO 2 , co-doped WFe–TiO 2 and tri-doped WFeMo–TiO 2 have significantly reduced the band gap. The charge analysis for co-doped and tri-doped systems is provided. Absorption coefficient properties of all the models have demonstrated the absorption of the solar spectrum in both the ultraviolet (UV) and visible light regions. Single-doped, co-doped and tri-doped TiO 2 anatase models have shifted the conduction band towards the Fermi level and extended the absorption edge toward the visible light region, which enhanced the photocatalytic activity.