Highly Visible Light Active TiO2−xNx Heterojunction Photocatalysts

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• 作者：Vinodkumar Etacheri ; Michael K. Seery ; Steven J. Hinder ; Suresh C. Pillai
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：July 13, 2010
• 年：2010
• 卷：22
• 期：13
• 页码：3843-3853
• 全文大小：1082K
• 年卷期：v.22,no.13(July 13, 2010)
• ISSN：1520-5002

文摘

Nitrogen doped anatase-rutile heterojunctions are successfully synthesized through an ethylenediaminetetraacetic acid (EDTA) modified sol−gel process. An FT-IR study of EDTA modified TiO₂ gel confirms the existence of an ionic intermediate (as indicated by a Δν value of 233 cm⁻¹). Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Raman spectroscopy are employed to study the phase evolution, phase purity, and crystallite size of samples. Formations of O−Ti−N and N−Ti−N bonds in calcined samples are confirmed using XPS and FT-IR spectroscopy. All EDTA modified samples show significantly higher visible light photocatalytic activity than the unmodified sample. The most active nitrogen doped heterojunction obtained at 400 °C exhibits 9-fold visible light activity in comparison to the standard photocatalyst Degussa P-25. It is proposed that the photo excited electrons (from the visible midgap level) are effectively transferred from the conduction band of anatase to that of rutile causing effective electron−hole separation, which is responsible for the higher visible light activity and lower photoluminescence (PL) intensity.