Ce、N共掺杂锐钛矿相TiO_2光学性能的第一性原理研究

First-principles Study on Optical Performances of Anatase TiO_2 Co-doped with Ce/N

采用密度泛函理论研究了Ce、N共掺杂锐钛矿相Ti O2的电子结构、态密度和光学特性。计算结果表明,不同位置Ce、N共掺杂对Ti O2的杂质形成能、带隙和光学性质是有影响的。共掺杂带隙比单掺杂Ti O2的更窄,导致电子从杂质能级激发到导带的概率增大,这会提高共掺杂Ti O2的光量子效率。Ce、N共掺杂后Ti O2吸收带边红移至可见光区的更远处,光学吸收系数比单掺杂时更强,这主要是由Ce、N共掺杂的协同效应引起的。带边位置的计算结果表明掺杂Ti O2的强氧化还原能力得到保持。因此,Ce、N共掺后Ti O2在可见光区具有良好的光催化性能。

The electronic structure,density of state and optical properties of Ce and N co-doped anatase Ti O2 were investigated by first-principles calculations based on density functional theory. The calculated results indicate that the defect formation energy,band gap and optical performances will change at different substitutional position of Ce and N. Co-doping with Ce / N in Ti O2 results in band gap narrowing that increases the probability of electronic transition from the impurity energy levels to the conduction band,then improves the solar energy utilization. The synergistic effects of Ce and N co-doping lead to a decrease of the photon excitation energy from the valence band to the conduction band,which extends the redshift of absorption edge and enhances the visible-light absorption. Besides,the calculated results of band edge position suggest that the strong redox capacity of doping Ti O2 is still excellent. Therefore,Ce /N co-doped Ti O2 may induce an excellent visible-light photocatalytic activity.