S.M. Esfandfard
In this work, The influential parameters on photocatalytic activity of titania, more specifically anatase to rutile transformation and electronic structure in response to substitution of Ti with 3 d of transition metals have been investigated. The systematic computations of the formation and stability of crystalline energy of TiO2 anatase and rutile doped to intermediates 3d are performed using FHI-aims, a package based on the developed density functional theory. From the scrutiny of energy calculations of structures that were doped with 3d intermediates, it was found that all 3d impurities rutile were stable over the anatase phase, which determined the rutile stabilization strength in such systems as Co> Zn> Cu> Sc> Ni > Mn> Cr> Fe> V. This agent can reduce the percentage of anatase in the titanium compound and lead to lower activity. Electronic structure’s calculations show that V, Cr, Mn, Fe, Co and Ni dopants can cause photocatalytic activity in visible range by creation of defect levels in band gap. Partial density of state (pDOS) of titania showed that the d(Ti) and p(O) states have the main contribution of conduction band (CB) minimum and valance band (VB) maximum respectively. Presence of V impurity creates the defect sates in bottom of the conduction band giving rise a red shift in the gap. In case of Sc, Cu and Zn, the defect states of impurities aren’t seen in the gap.
