First-principles calculations of Ca/F co-doped anatase TiO2
Keywords:
Anatase TiO2, Ca/F codoping, electronic structure, first-principles, photocatalytic activityAbstract
In order to understand the improved photocatalytic activity of Ca/F co-doped TiO2,the lattice parameters, energy band structures, density of states and absorption spectraof pure, Ca doped, F doped and Ca/F co-doped anatase TiO2 were calculated by firstprinciples based on the density functional theory. It was found that the doping can resultin lattice distortion of TiO2, especially the biggest lattice distortion was generated bythe Ca/F co-doping. The forbidden energy band width of anatase TiO2 was broadenedby Ca or F doping, while it was reduced by Ca/F co-doping. The calculated electronicdensity of states indicated that Ca doping provided contribution to the valence band ofTiO2, and F doping resulted in the highest energy level occupied by electrons appearedin the conduction band. The energy band of TiO2 almost kept unchanged after Ca/Fco-doping except the reduction of forbidden band width. Therefore, the experimentallyobtained photocatalytic activity improvement of TiO2 co-doped with Ca and F mayhave resulted from the reduction of forbidden band width of TiO2.
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