中文摘要：

采用基于密度泛函理论（DFT）的平面波超软赝势方法（PWPP）,利用Material studio计算N, Fe, La三种元素掺杂引起的锐钛矿TiO2晶体结构、能带结构和态密度变化.并通过溶胶-凝胶法制得锐钛矿型本征TiO2, N, Fe共掺杂TiO2和N, Fe, La共掺杂TiO2；用X射线衍射和扫描电镜表征结构；紫外-可见分光光度计检测TiO2对甲基橙的降解效率变化.计算结果表明,由于N, Fe, La三掺杂TiO2的晶格体积、键长等发生变化,导致晶体对称性下降,光生电子-空穴对有效分离,同时在导带底和价带顶形成杂质能级, TiO2禁带宽度由1.78 eV变为1.35 eV,减小25%,光吸收带边红移,态密度数增加,电子跃迁概率提升,光催化能力增加.实验结果表明：离子掺杂使颗粒变小,粒径大小：本征TiO2〉N/Fe_TiO2〉N/Fe/La_TiO2,并测得N/Fe/La_TiO2发光峰425 nm,能隙减小,光催化能力比N/Fe_TiO2强,增强原因是杂质能级和电子态数量增加引起.

英文摘要：

Based on the plane wave method （PWPP） of densiy functional theory （DFT） we model the N, Fe, La three elements co-doped anatase TiO2 crystal structure and calculate its band structure and density of states with Material Studio. By the sol-gel method, the intrinsic anatase TiO2 and the anatase TiO2 with N, Fe, La three elements co-doping are prepared and investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Results indicate that the changes of the N, Fe, La co-doped TiO2 lattice volume and its bond length will result in a decline of the crystal symmetry and the effective separation of the electron-hole pair. Impurity level appearing at the bottom of the conduction band and at the top of valence band leads to the decrease of the TiO2 forbidden band width（1.78 eV to 1.35 eV, reduced by 25%）, the red shift of light absorption edge, the increase of density of states as well as, the improve ment of electron transition probability and the photocatalytic efficiency of TiO2. Ion doping makes the particles in doped TiO2 become smaller, i.e. the size of particles in TiO2 〉N/Fe TiO2 〉N/Fe/La TiO2, the emission peak of the N/Fe/La： TiO2 is 425 nm and its energy gap is smaller than that of the intrinsic TiO2. The measured N/Fe/La： TiO2 photocatalytic ability is stronger than the N/Fe： TiO2, the origin can be due to the increasing number of the electronic states and theimpurity energy levels.