First principles calculations of electronic and optical properties of Mo-doped rutile TiO2

Based on the density functional pseudopotential method, the electronic structures and the optical properties for Mo-doped rutile TiO2 are comparatively investigated in detail. Mo substitution of the Ti sites induces effective reduction of the band gap of TiO2, and the band gap being continuously reduced when increasing Mo doping level. For the pure TiO2, the Fermi level locates at the valence band maximum, while it shifts to the conduction band and exhibits metal-like characteristic after Mo atoms are introduced into the TiO2 supercell. The calculated optical properties indicate that the optical energy gap is increased after Mo doping. More importantly, absorption in the visible-light region is found, which originates from the intraband transition of the Mo 4d bands and the conduction bands. These calculations provide electronic structure evidence that, the Mo-doped rutile TiO2 system could be a potential candidate for photoelectrochemical application due to the increase in its photocatalytic activity.

Research highlightsMo has been used to dope TiO2 for photocatalytic applications, showing the effects to make the materials catalytically active under visible light. But little has been done to quantify whether effective red-shift has been caused by Mo doping of rutile TiO2, and no effort has been made for a theoretical characterization of the Mo effects on its electronic and optical properties. In this paper, the aim of work is to study the electronic and optical properties of TiO2 doping with the 4d transition metal Mo using the density functional method, and some fundamental information which is similar to the experiments.