Effect of Ag doping concentration on the electronic and optical properties of anatase TiO2: a DFT-based theoretical study
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The electronic and optical properties of pure and Ag-doped anatase TiO2 have been calculated by spin-polarized density functional theory. Ag-doped TiO2 with different Ag doping concentrations ranging from 2.08 to 8.33 % was investigated, and the electronic and optical properties evaluated. Substitutional Ag doped at Ti sites introduced Ag 4d states just above the valence-band maximum, which may help in shifting visible-light excited electrons to the conduction band. Our results show that increasing the doping concentration will enhance visible-light absorption up to Ag doping concentration of 6.25 %; however, further increase of the doping concentration leads to a decrease in visible-light absorption. These results indicate the possibility of tailoring the band gap and optical absorption of TiO2 doped with Ag by varying the doping concentration. The enhanced visible-light absorption for Ag-doped TiO2 with doping concentration of 6.25 % may be due to the existence of widely distributed Ag 4d states above the valence-band maximum and the optimal doping concentration. Ag doping shifted the absorption edge of TiO2 towards visible light, consistent with recent experimental results. Our calculation results provide a reasonable explanation for the experimental findings.
KeywordsAg-doped TiO2 DFT Optimal doping
This work has been financially supported by the National Natural Science Foundation of China (grant no. 51072019), the National High Technology Research and Development Program of China (grant no. 2012AA030302), and the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure under grant SKL201112SIC.