中文摘要：

本文基于第一性原理的平面波超软赝势计算TiO2和Eu-N-TiO2的几何结构、重叠布局数、Mulliken电荷、能带结构、态密度、电荷分布和光吸收.研究发现Eu和N共掺后有额外电子进入价带,使费米面上移且态密度变平缓,有利于载流子的产生和运输.共掺后产生了离子性更强的化学键,能吸收波长较长的光,并且禁带宽度降低,发生红移,提高了TiO2的光催化活性.同时采用了溶胶-凝胶法制备TiO2和Eu-N-TiO2复合纳米材料,对其进行XRD、UV-vis和SEM表征,并通过光降解甲基橙评估其光催化活性.研究发现Eu和N共掺能抑制TiO2从锐钛矿相向金红石相转变和晶粒长大,有利于提高TiO2的光催化活性.此外,Eu-N-TiO2在250nm后的紫外光和可见光下的光催化活性都比TiO2高,经过2个小时照射,在紫外光和可见光下对甲基橙的光降解率分别达到98.54%和69.59%.

英文摘要：

The geometry,overlap population,Mulliken charge,band structures,density of states,charge density and optical absorption of TiO2 and Eu-N-TiO2 were studied by using the plane-wave pseudopotential method based on the first-principles.It is found that there are many extra electrons moved into the valence band after Eu,N codoping.So that the Fermi face shifted up and the density of states became smooth.It is good for generation and transport of the carriers.After co-doping,the unit cell generated some chemical bonds which have higher ionicity.These chemical bonds can absorb longer wavelength light.The band gap reduced and the optical absorption curve red-shifted after co-doping,it can improve the photocatalytic activity of TiO2.At the same time,TiO2 and Eu-NTiO2 composite nano-materials were prepared by the sol-gel method and characterized by X-ray diffraction（XRD）,UV-vis absorbance spectroscopy（UV-vis）,scanning electron microscopy（SEM）.The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange.The results show that Eu and N co-doping can inhibit both the phase transformation of TiO2 from anatase phase to rutile phase and grain growth that can improve the photocat-alytic activity of TiO2.In addition,Eu-N-TiO2 has higher photocatalytic activity than TiO2 from 250nm to 800 nm,and the degradation rate under UV light and visible light is 98.54% and 69.59% after 120 min shining,respectively.