Abstract：The band structure, electronic density of states and absorption spectrum of W—N co-doped anatase TiO₂ were calculated using first principle based on the density functional theory. The results indicate that W—N co-doping does not change the band gap of anatase TiO₂, while N 2p doping energy level is incorporated into the band gap above the valence band maximum, and its Fermi energy level is located at the conduction band.W 5d orbital provides contributions to the bottom edge of valence band and conduction band, whereas N 2p contributes its orbital to the upper edge of valence band maximum and the isolated doping energy level located in the band gap. W—N co-doping enhances the absorption ability of anatase TiO₂ in the wave length range from 340 to 800 nm.

Keywords：doping; anatase; first principle