In order to evaluate the effects of oxygen vacancy on the electronic structure and absorption spectra of bismuth oxychloride (BiOCl), the structural parameters, electronic structures, formation energies and absorption spectra of the perfect BiOCl and BiOCl containing oxygen vacancy (BiO15/16Cl) were studied using first-principles method based on density functional theory. The simplified models for the possible formation mechanisms of oxygen vacancy, and the effective separation and lower recombination processes of photo-induced electron–hole pairs in BiO15/16Cl were built up and discussed. The calculated structural parameter error was less than 7.5%, showing that the present  approach was suitable. The calculated formation energies reveal that the existence of oxygen vacancy in BiOCl sample was very possible. The densities of states of BiO15/16Cl indicate that the oxygen vacancy would introduce a new electronic state in forbidden band compared with those of the perfect BiOCl, and this new electronic state could act as a capture center for excited electrons and, consequently, improve the effective separation of electron–hole pairs and be more beneficial for utilizing visible light. The absorption spectra show that BiO15/16Cl exhibits a new absorption peak at about 2.72eV (456nm) in the visible region, which was in good agreement with the experimental value of 468nm.

Effects of Oxygen Vacancy on the Electronic Structure And Absorption Spectra of Bismuth Oxychloride. X.Zhang, L.Zhao, C.Fan, Z.Liang, P.Han: Computational Materials Science, 2012, 61, 180–4