The band structures and optical absorption spectra of O vacancy and Ni ion doped anatase TiO2 were successfully calculated and simulated by a plane wave pseudopotential method based on density functional theory. From the calculated results, a phenomenon of “impurity compensation” was found: the lower formation energy for O vacancy than Ni impurity indicated that introducing the intrinsic defect of O vacancy into Ni ion doped TiO2 sample was very possible; the positive binding energy for the combination of O vacancy and Ni impurity indicated that two defects were apt to bind to each other; While Ni impurity produced the donor levels in the forbidden band of TiO2, Ni impurity with O vacancy produced the acceptor levels upon which the excitation led to the photogenerated electrons with high energy and transferability. The combination of absorption spectra for O vacancy and Ni impurity with O vacancy models could reproduce the experimental measurement very well.

A First-Principles Theoretical Simulation on the Electronic Structures and Optical Absorption Properties for O Vacancy and Ni Impurity in TiO2 Photocatalysts. Z.Zhou, M.Li, L.Guo: Journal of Physics and Chemistry of Solids, 2010, 71[12], 1707-12