氮对光催化性能的影响:TiO_2纳米球和纳米线对比研究

Nitrogen Effect on Photocatalytic Property: the Compared Study between TiO_2 Nanoballs and TiO_2 Nanowires

使用阳极氧化和氨气退火N化的方法制备了N掺杂的TiO2纳米球薄膜和纳米线薄膜.经过N掺杂TiO2纳米线薄膜与未掺杂纳米线可见光区的光吸收强度相差不大,能带宽度从未掺杂样品的3.2eV缩小为3.1eV.TiO2纳米球薄膜在可见光区的光吸收显著增强,能带宽度由未掺杂样品的3.2eV缩小为2.8eV,同时纳米球生长被抑制,其直径约为50nm,明显小于未掺杂TiO2样品的100mn.在可见光照射TiO2氮掺杂纳米线薄膜和纳米球薄膜降解4h后,溶液中亚甲基蓝的浓度分别降至45%和44%,N掺杂样品获得了优异的可见光光催化活性.研究表明N掺杂导致的O空穴浓度增加和能带宽度有效减小是其可见光区光催化活性增强的主要原因.

The nitrogen doped TiOz nanoball films and nanowire films were prepared by anodization and post annealing in NH3 gas. Nitrogen doped nanowire films have similar absorbance intensity compared with undoped nanowire films, and the en- ergy band gap narrowed to 3.1 eV compared with 3.2 eV of undoped samples. Nitrogen doped TiO2 nanoball films exhibit a strong absorbance in visible light region and the energy band gap narrowed to 2.8 eV compared with 3.2 eV of undoped nanoball samples, at the same time the nitrogen doping retards nanoball growth and the diameter of nitrogen doped nanoball is about 50 nm which is smaller than the diameter of undoped nanoball （100 nm）. The concentrations of methyl blue decrease to nearly 45% and 44% in 4 hours under visible light irradiation for nitrogen doped nanowire films and nanoball films respectively. The results show that nitrogen doped samples have superior photocatalytie properties. The results indicate that the increase of oxygen vacancies density deduced by nitrogen doping and the effect decrease of energy band gap are the two main reasons for enhanced photocatalytic activities in visible light region.