Chalcogen Element (S, Se and Te) Doped Anatase TiO2 by DFT Calculations

  • Dr Jianwei Zheng, Institute of High Performance Computing, Singapore
  • Atreyee Bhattcahrayya, School of Chemical & Biomedical Enginnering, Nanyang Technological University, Singapore
  • Dr Ping Wu, Institute of High Performance Computing, Singapore
  • Associate Prof Zhong Chen, School of Materials Science and Engineering, Nanyang Technological University, Singapore
  • Dr Rong Xu, School of Chemical & Biomedical Enginnering, Nanyang Technological University, Singapore
  • Dr James Highfield, Institute of Chemical and EngineeringSciences, Singapore
  • Dr Zhili Dong, School of Materials Science and Engineering, Nanyang Technological University, Singapore

    • Modification of the electronic structure, defect formation and optical properties of anatase TiO2 through chalcogen element (S, Se and Te) doping was studied by DFT calculation.
    All chalcogen element doping prefer to substitute Ti atom at O-rich condition and O atom at Ti-rich condition. Both anionic and cationic doping can extend the absorption edge of anatase TiO2 to visible region but anionic Se and Te doping is more effective. Anionic S and Se doping generate states just above the top of the valence band but anionic Te doping generates broad localized gap states. All cationic chalcogen element doping generates sharp localized gap states. The position of these gap states shifts towards the conduction band with increasing the atomic number.
    Anionic doping slightly decreases the oxygen vacancy formation energy but drastically decreases the titanium vacancy formation energy, indicating that these chalcogen element doped anatase TiO2s are probably good photocatalysts for water splitting under the visible light.
    Mulliken charge analysis and molecular bonding analysis show that Ti - chalcogen element bonds display more covalent nature when the atomic number of chalcogen elements increases.