The substitute of metal ions in the titanium lattice was confirmed by the Ti 2p and O 1s peak shift from the un-doped TiO2
thin film.
Table 1 shows changes in the Ti and O peak position with respect to the dopants. As evident from Table 1, there is an increase in the binding energy from 0.16 to 0.38 eV for the Ti 2p3/2, which confirms the metal ions (Ni, Fe and Nb) substitution in the Ti lattices.