摘要
以液相法制备了水溶态纳米TiO2,并通过X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶红外光谱仪(FTIR)对纳米TiO2的结构和组成作了细致分析。并对其紫外-可见光谱(UV-Vis spectrum)和荧光发光光谱(PL spectrum)进行了分析。结果发现纳米TiO2呈现较好的锐钛矿型,平均粒径为5 nm。水溶态纳米TiO2由于吸附而在表面形成了Ti—OH和Ti—H2O的表面态,其能级位于其价带以上约0.6和0.54eV;500℃热处理后样品的表面吸附水基本消失,但OH-仍然存在,同时在纳米TiO2晶格中出现了氧空位,其能级位于价带以上3.13 eV。对于水溶态纳米TiO2,表面复合是电子-空穴对的主要复合过程;热处理后的样品,由于表面态遭到破坏,粒子半径变大,直接复合成为电子-空穴对的主要复合过程,同时还伴随有通过氧空位的间接复合和通过Ti—OH的表面复合。
The nanometer TiO2 was prepared by sol-gel method. The structure and composition of the nanometer TiO2 were analyzed in detail by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, and Fourier transform infrared spectrometry （FTIR）. The UV-visible spectrum and fluorescence spectrum were studied too. The results show that the nanometer TiO2 contains better anatase crystallinity, and the average size of the nanometer TiO2 is about 10 nm. The surface states, Ti-OH and Ti--H2O, are formed on the surface of nanometer TiO2 in aqueous solution because of high absorption ability, whose energy levels are about 0. 6 and 0. 54 eV above the valence band, respectively. The surface state T^HzO is destroyed after heat treatment at 500 ℃ for two hours, but the Ti--OH still exists, and the crystalline lattice presents some oxygen vacancies whose energy level is about 3.13 eV above valence band. For the nanometer TiO2 aqueous solution, the surface recombination of electron-hole Pairs via Ti-OH and Ti--H2O is the main recombination manner, but for the samples after heat treatment, direct recombina tion from conduction band to valence band is the main recombination manner, due to the destroying of surface states, with the companion of indirect recombination via oxygen vacancy and surface recombination via Ti-OH.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2006年第2期208-212,共5页
Spectroscopy and Spectral Analysis
基金
国家"863"项目(2002AA335030)资助项目
关键词
表面复合
表面态
纳米二氧化钛
电子-空穴对
Surface recombinationg Surface states
Nanometer TiO2
Electron-hole pairs
