Band structure and photocatalytic properties of N/Zr co-doped anatase TiO2 from first-principles study

The photocatalytic activity of anatase Titania (TiO2) co-doped with zirconium (Zr) and nitrogen (N) with respect to TiO2 monodoped with Zr or N is reported. Density functional theory (DFT) calculations have been carried out to describe the formation energy and electronic structure of pure, Zr-, N- and N/Zr-co-doped anatase TiO2. Substitutional locations of Zr and N in the TiO2 lattice were considered: an O (Ti) atom is replaced by an N (Zr) atom. It was found that the N/Zr-co-doped case narrowed the band gap by about 0.28 eV, brought the N 2p gap states closer to the valence band, enhancing the lifetimes of photo-excited carriers, while Zr-doped TiO2 did not change the construction of band. These findings provide good theoretical understanding for recent experimental results.

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► The photocatalytic activity of N-doped TiO2 is limited due to the N 2p gap states.
► Zr-doping did not change the band gap of pure TiO2.
► Addition of Zr to N-doped TiO2 brought N 2p closer to VB, and narrowed the band gap.