A series of Ti-doped SnO2(110) surfaces with different oxygen vacancies were investigated by means of first principles DFT calculations combined with a slab model. Three kinds of defective SnO2(110) surfaces were considered, including the formations of bridging oxygen (Ob) vacancy, in-plane oxygen (Oi) vacancy, and the coexistence of Ob and Oi vacancies. The results indicated that the Ti dopant preferred the fivefold-coordinated Sn site on the top layer for the surface with Ob or Oi vacancy, while the replacement of sublayer Sn atom becomes the most energetically favorable structure if the Ob and Oi vacancies were presented simultaneously. Based on analyzing the band structure of the most stable configuration, the presence of Ti leads to the variation of the band gap state, which was different for three defective SnO2(110) surfaces. For the surface with Ob or Oi vacancy, the component of the defect state was modified, and the reaction activity of the corresponding surface was enhanced. Hence, the sensing performance of SnO2 may be improved after introducing Ti dopant. However, for the third kind of reduced surface with the coexistence of Ob and Oi vacancies, the sub-layer doping has little influence on the defect state, and only in this case, the Ti doping state partly appears in the band gap of SnO2(110) surface.

Effects of Ti Doping at the Reduced SnO2(110) Surface with Different Oxygen Vacancies: a First Principles Study. H.Jin, W.Lin, Y.Zhang, J.Zhu, Y.Li, Y.Zhang, K.Ding, X.Huang, W.Chen: Theoretical Chemistry Accounts, 2012, 131[6], 1231