具可见光活性的氮掺杂二氧化钛光催化剂

以氮掺杂为代表的非金属掺杂型TiO₂光催化剂被誉为“第二代光催化材料”。本文首先系统评述了氮掺杂二氧化钛的制备方法，然后详细阐述了在N掺杂TiO₂研究中关于其可见光活性机制以及掺杂N在TiO₂晶格中的存在状态等方面的争议。N掺杂TiO₂粉末的制备方法主要有氨气气氛下的热处理工艺、水解沉淀法、溶胶－凝胶法以及机械化学法等；N掺杂TiO₂薄膜的制备方法主要包括磁控溅射法、脉冲激光沉积法以及金属有机化学气相沉积法等。已提出的关于N掺杂TiO₂可见光活性机制的观点有N2P与O2P能级相杂化、形成N 2p孤立能态、氧空位的作用以及具顺磁性特征的杂质敏化。关于掺杂N在TiO₂晶格中存在状态的分歧在于XPS N 1s谱中特征峰的位置及其归属的解析。文章最后指出了氮掺杂二氧化钛催化剂研究中有待解决的问题及今后的发展方向。

Nitrogen Doped TiO2 Photocatalysts with Visible-Light Activity

Nonmetal-doped TiO2 photocatalysts are considered the second-generation photocatalytic materials, in which nitrogen doped TiO2 is the representative. The methods for preparing nitrogen doped TiO2 are systematically reviewed, and some controversies concerning the origin of visible-light responses for N-doped TiO2 and the state of N doped in TiO2 matrix are explicated in this paper. The methods for preparing nitrogen doped TiO2 powders mainly include the heat treatment under NH3 flow, the hydrolytic precipitation, the sol-gel process and the mechanochemical method. The methods for preparing nitrogen doped TiO2 films mainly include magnetron sputtering, pulsed laser deposition and metal-organic chemical vapor deposition. Several different mechanisms for the visible-light activity of N-doped TiO2 have been proposed, which are the mixing of N 2p and O 2p orbits, the formation of an N-induced isolated narrow band, the presence of oxygen vacancies, and the sensitization by paramagnetie impurity. The controversy concerning the state of N doped in TiO2 matrix lies in the assignment of the peak feature in the XPS N 1 s spectrum for nitrogen doped TiO2. Finally, the problems in the study of nitrogen doped TiO2 photocatalysts and the future developing trends are presented.