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Enhanced visible light photocatalytic activity of N-doped TiO2 in relation to single-electron-trapped oxygen vacancy and doped-nitrogen

Paper ID Volume ID Publish Year Pages File Format Full-Text
47146 46462 2010 7 PDF Available
Title
Enhanced visible light photocatalytic activity of N-doped TiO2 in relation to single-electron-trapped oxygen vacancy and doped-nitrogen
Abstract

Although numerous papers are available about the origin of visible light photocatalytic activity of N-doped TiO2, it still remains conflicting how nitrogen-doping affects the visible light photocatalytic activity of TiO2. Thus N-doped TiO2 was prepared by heat treatment of commercial P25-TiO2 in flowing NH3, aiming at revealing the origin of visible light sensitization of N-doped TiO2. The resulting N-doped TiO2 was characterized by means of electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS), diffusion reflectance spectrometry (DRS), and X-ray diffraction (XRD). Results indicate that N-doped TiO2 shows triplet g value ESR signals (g = 1.987, 2.004 and 2.024), which is attributed to single-electron-trapped oxygen vacancy (denoted as SETOV) in a certain chemical environment. Its visible light photocatalytic activity is proportional to the intensity of the triplet g value signals, which implies that the visible light photocatalytic activity of N-doped TiO2 is closely correlated to the formation of SETOV during heat treatment in flowing NH3. Besides, N-doped TiO2 catalyst calcinated at 600 °C possesses the highest photocatalytic activity, but that calcinated at 700 °C has drastically decreased photocatalytic activity and shows no XPS signal of nitrogen. Moreover, N-doped TiO2 shows visible light absorption in a wavelength range of 400–520 nm, which is attributed to the formation of SETOV and phase transformation from anatase to rutile. It is suggested that the visible light photocatalytic activity of N-doped TiO2 is co-determined by the formation of SETOV in TiO2 matrix and existence of doped-N on the surface. In other words, in the absence of either SETOV in TiO2 matrix or doped-nitrogen on the surface, N-doped TiO2 will not show visible light photocatalytic activity; and the higher the SETOV concentration is, the better the visible light photocatalytic activity will be.

Graphical abstractESR results of P25-TiO2 and N-doped TiO2. The results were obtained at room temperature in air.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Triplet g value ESR signal ascribed to single-electron-trapped oxygen vacancy was observed for N-doped TiO2. ▶ The visible light photocatalytic activity of N-doped TiO2 is proportional to the intensity of triplet ESR signal. ▶ Doped-N functions to prevent photoinduced electrons and holes from recombination.

Keywords
N-doped TiO2; Catalyst; Visible light photocatalytic activity; Single-electron-trapped oxygen vacancy
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Enhanced visible light photocatalytic activity of N-doped TiO2 in relation to single-electron-trapped oxygen vacancy and doped-nitrogen
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 100, Issues 1–2, 11 October 2010, Pages 84–90
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us