摘要
The electron structure and optical properties of C-TiO_(2)(001)surface under external electric field were studied by DFT method.After carbon doping,a new impurity level is introduced in the bandgap region of TiO_(2)(001)surface,and leads to the decrease of band gap,contributing to the shift of optical absorption to the visible region.When external electric field is applied across the C-TiO_(2)(001)surface,the band gap is further reduced with the increase of the electric field intensity from 0.1 eV to 0.5 eV.The electric field over 0.5 eV induces the electronic polarization.The spin-up bands show a gap,while spin-down electrons correspond to a metallic state.The energy gap of spin-up band decreases with increasing the electric field from 0.7 eV to 1.0 eV.The optical absorption of C-TiO_(2)(001)shifts to long wavelength compared with pure TiO_(2)(001).The electric filed make the optical absorption red-shift further,and the shift increases with an increase of the electric field,especially in the range of 0.7 eV-1.0 eV.The results show that the combined effect of carbon doping and electric field can enhance the photocatalytic activity of TiO_(2)(001)surface in visible region.
基金
This research was supported by Guangxi Natural Science Foundation(No.2017GXNSFAA198247).
