Effects of acceptor–donor complexes on electronic structure properties in co-doped TiO2: A first-principles study

•Band structure and band edges can be modified by monodoping or codoping in anatase TiO2.•The compensated acceptor–donor pairs in the co-doped TiO2 will improve the photoelectrochemical activity.•(S+Zr)-codoped TiO2 has the ideal band gap and band edge for photoelectrochemical experiments.

We theoretically investigate the doping effects induced by impurity complexes on the electronic structures of anatase TiO2 based on the density functional theory. Mono-doping and co-doping effects are discussed separately. The results show that the impurity doping can make the band-edges shift. The induced defect levels in the band gaps by impurity doping reduce the band gap predominantly. The compensated acceptor–donor pairs in the co-doped TiO2 will improve the photoelectrochemical activity. From the calculations, it is also found that (S+Zr)-co-doped TiO2 has the ideal band gap and band edge, at the same time, the binding energy is higher than other systems, so (S+Zr)-co-doping in TiO2 is more promise in photoelectrochemical experiments.

Graphical abstractBand structure optimization of TiO2 is one of the important topics in photoelectrochemical experiments. Here we theoretically investigate the effects of substitution doping on the electronic structures of anatase TiO2. The figure shows the calculated band edge positions of different ions doped TiO2. The black points represent the results in which the impurity levels are neglected, however, the red points represent the results in which the impurity levels are taken. Comparing with pure TiO2, It is obvious that the valence band edges of F, S, Nb and Zr doped TiO2 are slightly shifted downward, however, the conduction band edges are slightly shifted upward, which means that the impurity doping could enhance the redox power of TiO2 in general. From the calculations of the co-doping cases, it is found that (S+Zr)-codoped TiO2 has the ideal band gap and band edge, at the same time the binding energy is big, so (S+Zr)-co-doping in TiO2 is more expected in photoelectrochemical experiments.Figure optionsDownload full-size imageDownload as PowerPoint slide