Electronic structure of Gd/N co-doped anatase TiO2 by first-principles calculations

Abstract

The lattice parameters, energy band structures, density of states, and optical absorption spectra of Gd-doped, N-doped, and Gd/N co-doped anatase TiO2 were calculated by the first-principles based on the density functional theory. The calculated results indicate that the three kinds of doping all induce lattice distortion for TiO2, but the structures still keep unchanged. Gd doping introduces an empty energy band in the forbidden band of TiO2, and N doping introduces an impurity energy level above the maximum valence band. Gd/N co-doping forms an impurity energy level and a full-filled energy band in the forbidden band of TiO2, where the impurity energy level lies above the full-filled energy band. The experimental results for the photocatalytic activity enhancement of TiO2 by the Gd/N co-doping can be explained perfectly from the calculation results.