N,Fe,La三掺杂锐钛矿型TiO_2能带调节的理论与实验研究  

Theoretical and experimental studies on N,Fe,La co-doped anatase TiO_2 band adjustment

作　　者：王庆宝[1] 张仲[1] 徐锡金[1] 吕英波[2] 张芹[3] 

机构地区：[1]济南大学物理科学与技术学院,济南250022 [2]山东大学威海分校空间科学与物理学院,威海264209 [3]山东交通学院数理系,济南250023

出　　处：《物理学报》2015年第1期270-276,共7页Acta Physica Sinica

基　　金：国家青年科学基金(批准号:11104114);国家自然科学基金(批准号:11304120);山东省优秀中青年科学家奖励基金(批准号:BS2012CL005)资助的课题~~

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Ti O2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Ti O2,N,Fe共掺杂Ti O2和N,Fe,La共掺杂Ti O2;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Ti O2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Ti O2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,Ti O2禁带宽度由1.78 e V变为1.35 e V,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Ti O2>N/Fe_Ti O2>N/Fe/La_Ti O2,并测得N/Fe/La_Ti O2发光峰425 nm,能隙减小,光催化能力比N/Fe_Ti O2强,增强原因是杂质能级和电子态数量增加引起.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.

关 键 词：TIO2 掺杂 第一性原理 溶胶凝胶 

分 类 号：O469[理学—凝聚态物理]