First-Principles Calculation of Bi-Doped Anatase TiO2

The electronic structures and optical properties of pure anatase TiO2 and Bi-doped anatase TiO2 were calculated using the plane-wave ultra-soft pseudo-potential (PWPP) method based on the density functional theory (DFT). The results indicate the populations of Ti atoms decline and those of O atoms increase. The Bi doping introduces impurity energy level into the forbidden band. It was found that the impurity energy level is composed of Bi6s, O2p and Ti3d orbitals. The forbidden band width of the Bi-doped anatase TiO2 increases a little. But the detrimental effect arose from the enlargement of forbidden band is offset by the function of the impurity energy level, which results in a red shift of the absorption edge and a strong absorption ability for the Bi-doped anatase TiO2.