Spectrum redshift effect of anatase TiO_2 codoped with nitrogen and first transition elements

作     者：辜永红 蔡从中 冯庆 李艳华 

作者机构：Department of Applied Physics Chongqing University Chongqing Key Laboratory on Optoelectronic Functional Materials Chongqing Normal University 

出 版 物：《Chinese Optics Letters》 (中国光学快报（英文版）)

年 卷 期：2014年第12卷第9期

页      面：59-65页

核心收录：

学科分类：0808[工学-电气工程] 081704[工学-应用化学] 0809[工学-电子科学与技术（可授工学、理学学位）] 07[理学] 08[工学] 0817[工学-化学工程与技术] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 070301[理学-无机化学] 0702[理学-物理学] 

基　　金：supported by the National Natural Science Foundation of China(Nos.61274128 and 61106129) the Natural Science Foundation of Chongqing(No.CSTC2013JCYJA0731) 

主　　题：Atoms Chromium Conduction bands Density functional theory Doping (additives) Energy gap Light Light absorption Manganese Photocatalysis Refractive index Scandium Transition metals 

摘      要：The electronic and optical properties, including band structure, density of states （DOS）, absorption rate, refractive index, and dielectric function, of anatase TiO2 codoped with N and first transition elements are investigated using the plane wave pseudopotential method based on the density functional theory. The calculation results show that TiO2 codoping with N and first transition elements （Sc, V, Cr, Mn, and Fe） lead to significant reduction of conduction band relative to the Fermi level, reduction of band gap width, formation of new donor, and acceptor impurity levels below the conduction band and above the valence band, and cause some redshifts of optical absorption band edge with the amount of redshift decrease in the following order： N-Fe 〉 N-Cr 〉 N-Mn. Further, the synergistic effect of shallow donor and acceptor levels enhances light excitation for effective separation of electron-hole pairs and enhancement of light absorption ability, thereby increasing the TiO~ photocatalytic properties. This study reveals that the visible-light absorption ability of the codoped anatase TiO2 decreases in the order of N Fe 〉 N Cr 〉 N-Mn 〉 N-Sc 〉 N-V 〉 N, and does not monotonically follow the dopant atomic number. Especially, in N-Cr codoped TiO2, the 4s atomic orbit of Cr is not completely filled, which hybridized with the p electronic orbit most probably acts as photo-generated electron trap centers resulting in higher photocatalytie activity than that of N-Mn codoped TiO2.