Carbon-Doped TiO2 and Carbon, Tungsten-Codoped TiO2 through Sol鈥揋el Processes in the Presence of Melamine Borate: Reflections through Photocatalysis
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- 作者：Elaine M. Neville ; Michael J. Mattle ; David Loughrey ; Bashyam Rajesh ; Mahfujur Rahman ; J.M. Don MacElroy ; James A. Sullivan ; K. Ravindranathan Thampi
- 刊名：The Journal of Physical Chemistry C
- 出版年：2012
- 出版时间：August 9, 2012
- 年：2012
- 卷：116
- 期：31
- 页码：16511-16521
- 全文大小：419K
- 年卷期：v.116,no.31(August 9, 2012)
- ISSN：1932-7455
文摘
A series of C-doped, W-doped, and C,W-codoped TiO2 samples have been prepared using modified sol鈥揼el techniques. Reproducible inexpensive C-doping arises from the presence of melamine borate in a sol鈥揼el mixture, whereas W-doping is from the addition of tungstic acid to the sol. The materials have been characterized using elemental analysis, N2 physisorption (BET), thermogravimetric analysis, X-ray diffraction, Raman, X-ray photoelectron, UV鈥搗is spectroscopies, and photocatalytic activity measurements. Doping C and W independently results in an increased absorbance in the visible region of the spectrum with a synergistic effect in increased absorbance when both elements are codoped. The increased visible-light absorbance of the W-doped or codoped materials is not reflected in photocatalytic activity. Visible-light-induced photocatalytic activity of C-doped material was superior to that of an undoped catalyst, paving the way for its application under only visible-light irradiation conditions. A significant fraction of the spectral red shift commonly observed with doped catalysts might be due to the formation of color centers as a result of defects associated with oxygen vacancies, and bandgap-related narrowing or intragap localization of dopant levels are not the only factors responsible for enhanced visible-light absorption in doped photocatalysts. Furthermore, bandgap narrowing through increases in the energy of the valence band may actually decrease photo-oxidation activity through a curtailment of one route of oxidation.