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化学学报
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化学学报 ›› 2007, Vol. 65 ›› Issue (23): 2693-2700. 上一篇    下一篇

研究论文

掺氮TiO2可见光降解有机污染物的比较研究

方艳芬, 黄应平*, 刘立明, 罗光富   

  1. (三峡大学Alan G. MacDiarmid (艾伦•麦克德尔米德)再生能源研究所 宜昌 443002)
  • 投稿日期:2007-01-25 修回日期:2007-05-21 发布日期:2007-12-14
  • 通讯作者: 黄应平

Comparative Research on Degradation of Organic Pollutants with Nitrogen-Doped TiO2 Photocatalyst under Visible Light

FANG Yan-Fen; HUANG Ying-Ping*; LIU Li-Ming; LUO Guang-Fu   

  1. (Alan G. MacDiarmid Research Institute for Renewable Energy, Three Gorges University, Yichang 443002)
  • Received:2007-01-25 Revised:2007-05-21 Published:2007-12-14
  • Contact: HUANG Ying-Ping

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用溶胶-凝胶法制备了不同掺杂量的N/TiO2复合纳米粉末, 采用X射线衍射(XRD)、扫描透镜(TEM)、紫外-可见反射吸收光谱(UV-vis)对催化剂进行了初步表征. 通过X射线光电子能谱(XPS)、元素分析仪(EA)测定其含氮量. XPS分析结果显示TiO2晶格中的氧被氮原子取代, N/TiO2表面存在Ti3＋离子; 紫外-可见反射吸收光谱测得不同掺杂量的N/TiO2的禁带宽度(Eg), 推测在TiO2价带上方生成了由N诱导产生的中间带, 当氮、钛摩尔比为0.0880时N/TiO2的Eg最小, 为2.50 eV. 在可见光下, 以酸性桃红(SRB)和无色小分子对氯苯酚(4-CP)作为可见光活性实验的探针反应, 确定了最佳掺杂比为nN/nTi＝0.0880. 结果表明, 最佳掺杂量下N/TiO2能显著降解SRB和4-CP, 通过测定ESR, IR, TOC, COD, 重点比较了TiO2在掺杂N前后在降解SRB和4-CP时的差异, 包括氧化物种、矿化率、最终产物等, 证明在可见光下, N/TiO2的降解机理为电子从独立的N 2p轨道激发到Ti 3d轨道, 产生羟基自由基等氧化物种, 达到降解有机物的目的.

关键词: TiO2, 氮掺杂, 光催化, 降解

TiO2 nanoparticles doped with different content of nitrogen were prepared by sol-gel method, and preliminarily characterized by means of XRD, TEM and UV-vis spectra. The concentration of nitrogen of N/TiO2 was detected using XPS and elemental analyzer method (EA). It was confirmed by XPS that oxygen sites were substituted by nitrogen atoms and Ti3＋ species was formed on the surface of the nitrogen-doped titania; UV-visible reflectance spectra measured the band gap (Eg) of nitrogen-doped titania in different content, which indicated that an N-induced midgap level was formed from above the valence band (O 2p). The Eg of N/TiO2 could be estimated to be 2.50 eV when the molar ratio of N to Ti was 0.0880, which was narrowest. The photocatalytic degradation of sulforhodamine-B (SRB) and 4-chlorophenol (4-CP) in aqueous solution was used as probe reactions to evaluate their photocatalytic activity with different doped content. It indicated that the N/TiO2 powder with molar ratio nN/nTi＝0.0880 exhibited highly catalytic activity for degradation of SRB under visible light irradiation. The formed oxidation species, total organic carbon (TOC), chemical oxygen demand (CODCr) and infrared spectrophotometry (IR) assays showed that the mechanism of photocatalytic degradation involved the excitation of electrons from the isolated N 2p orbitals to the Ti 3d orbitals, generating •OH for degradation of organic compounds.

Key words: TiO2, nitrogen-doped, photocatalysis, degradation