First-principles calculations on Hg-doped anatase TiO2 with and without O vacancy

•We calculated the electronic properties of Hg doped TiO2 with and without O vacancy.•Impurity energy levels appear in the Hg doped TiO2 with and without O vacancy.•The absorption edge of Hg-TiO2 shows red shift.

The lattice parameters, band structures, electronic density of states and absorption spectra of Hg-doped anatase TiO2 with and without O vacancy were calculated using the first-principles method based on the density functional theory. It was found that the Hg doping results in the expansion of the supercell volumes. The energy band gap of the Hg-doped anatase TiO2 without O vacancy is narrowed, while that of the Hg-doped anatase TiO2 with O vacancy is widened. The calculated results indicate that the absorption edges of the Hg-doped anatase TiO2 with and without O vacancy show blue shift and red shift, respectively.