Tailoring the electronic and optical properties of rutile TiO2 by (Nb + Sb, C) codoping from DFT + U calculations

The electronic structures and optical properties of the rutile TiO2 doped by C, (2Sb, C), (2Nb, C), (Nb + Sb, C) have been investigated by density functional theory plus U calculations. It is found that (2Sb, C), (2Nb, C), (Nb + Sb, C) codoping results in band gap narrowing, due to the appearance of the mid-bandgap states from C 2p and the introduction of Sb 5s and Nb 4d states. In addition, the rutile TiO2 codoped by (Nb + Sb, C) and (2Nb, C) is much more effective for the enhancement of visible light absorption than that for C monodoping and (2Sb, C) codoping.