物理化学学报 >> 2010, Vol. 26 >> Issue (05): 1401-1407.doi: 10.3866/PKU.WHXB20100526

量子化学及计算化学 上一篇    下一篇

V掺杂锐钛矿相TiO2的光吸收特性

徐凌, 唐超群, 黄宗斌   

  1. 华中科技大学物理学院, 武汉 430074
  • 收稿日期:2009-11-23 修回日期:2010-01-19 发布日期:2010-04-29
  • 通讯作者: 唐超群 E-mail:cqtang@public.wh.hb.cn

Light Absorption Properties of V-Doped Anatase TiO2

XU Ling, TANG Chao-Qun, HUANG Zong-Bin   

  1. School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
  • Received:2009-11-23 Revised:2010-01-19 Published:2010-04-29
  • Contact: TANG Chao-Qun E-mail:cqtang@public.wh.hb.cn

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摘要：

使用V2O5和乙醇作为V掺杂TiO2的滴加液, 运用溶胶-凝胶方法制备了不同浓度的V掺杂锐钛矿相TiO2的薄膜样品. 对这些样品进行了紫外-可见透射光谱实验, 发现V 掺杂锐钛矿相TiO2的光谱响应范围向可见光区域移动, 掺杂浓度为1.0%(摩尔分数)时红移效果最明显. 此外, 运用第一性原理, 对V掺杂锐钛矿相TiO2的电子结构进行了研究, 并运用能带结构理论对实验现象进行了解释. 研究中发现: 在V掺杂锐钛矿相TiO2后, 随着V浓度的增加, TiO2的禁带宽度逐渐减小, 光谱响应范围扩大, 能提高它的可见光响应; 但是由于掺杂后价带与导带比较接近, 容易形成新的空穴-电子复合中心, 以及导带区域V 3d轨道上电子与Ti 3d轨道上的电子强关联作用也会降低电子的还原性, 所以V浓度的增加会使TiO2的光催化性能降低. 理论上计算出在V掺杂浓度为6.25%(摩尔分数)时, TiO2的光吸收边红移最大, 与实验得到的变化趋势相吻合.

关键词: V掺杂, 锐钛矿相TiO2, 能带结构, 吸收光谱

Abstract:

Vanadium-doped anatase TiO2 was prepared by a sol-gel method while V2O5 and ethanol were used as vanadium precursors. UV-Vis transmissivity spectra revealed that the spectral response of the V-doped TiO2 shifted to the visible light region. The optimum vanadium content was 1.0% (molar fraction). Furthermore, we performed first-principles calculations on the electronic band structure of the V-doped anatase TiO2 and explained some experimental phenomena. Our results indicate that the bandgap becomes narrow and the TiO2 spectral response increases with the doping concentration increases. The valence band and the conduction band are so close that the cavities and electrons easily recombine. Additionally, strong correlation of the electron of the V 3d orbital to the Ti 3d orbital electron results in the low dispersibility of the electron on the V 3d orbital. Therefore, the photocatalytic activity of V-doped TiO2 becomes weak with the increasing of doping concentration. When the optimum phosphorus content in our calculation is 6.25% (molar fraction), the red shift of TiO2 light absorption band is the largest, which is in agreement with the experimental trend.

Key words: V-doping, Anatase TiO2, Energy band structure, Absorption spectrum

MSC2000: 

  • O641