引用本文:代学伟,吴 江,齐雪梅,等.Fe掺杂TiO2催化剂制备及其光催化脱汞机理[J].环境科学研究,2014,27(8):827-834.
DAI Xue-wei,WU Jiang,QI Xue-mei,et al.Preparation of Fe-Doped Titania by Sol-Gel Method and Photocatalytic Removal of Gaseous Mercury[J].Reserrch of Environmental Science,2014,27(8):827-834.]
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Fe掺杂TiO2催化剂制备及其光催化脱汞机理
代学伟1, 吴 江1, 齐雪梅2, 吴 强2, 何 平1, 李 忺1
1.上海电力学院能源与机械工程学院, 上海 200090 ;2.上海电力学院环境与化学工程学院, 上海 200090
摘要:
采用溶胶-凝胶法制备Fe-TiO2(Fe掺杂纳米二氧化钛)催化剂,通过XRD(X射线衍射仪)、SEM(扫描电镜)、EDX(能量色散X射线光谱仪)和UV-Vis谱对其形态、结构、组成和性质进行表征. 采用Fe-TiO2催化剂脱除气态Hg0(元素汞),研究了该催化剂在紫外光和可见光下的脱汞效果,并考察了Fe3+的最佳掺杂比. 结果表明:在Fe-TiO2光催化剂中,TiO2以锐钛矿相形态存在,当Fe3+掺杂浓度〔以n(Fe)/n(Ti)计〕达到0.010时,所制备的Fe-TiO2在紫外光和可见光下的脱汞率均达到最大,分别为54.76%和18.92%. 提出了Fe-TiO2光催化脱汞的可能机制:Fe3+掺入TiO2结构中,使TiO2的导带与Fe3+的d轨道发生重叠,导致TiO2能带变窄,从而扩展了可见光的响应范围;Fe3+在TiO2中作为一个浅俘获阱,当其俘获光生电子以后,光生空穴能够继续扩散到TiO2表面发生表面化学反应,生成具有强氧化性的超氧自由基O2-和·OH,对Hg0进行氧化;当Fe3+掺杂浓度大于0.010时,由于过多的Fe3+成为了光生电子和光生空穴的俘获位,从而使俘获的电子-空穴对通过量子隧道效应复合的概率增加,同时,活性氧化物种O2-和·OH相互消耗,抑制了光催化效率.
关键词:  Fe3+掺杂  TiO2  溶胶-凝胶  光催化    可见光响应
DOI:
分类号:
基金项目:国家自然科学基金项目(50806041);上海市科学技术委员会科技创新行动计划项目(11dz1203402)
Preparation of Fe-Doped Titania by Sol-Gel Method and Photocatalytic Removal of Gaseous Mercury
DAI Xue-wei1, WU Jiang1, QI Xue-mei2, WU Qiang2, HE Ping1, LI Xian1
1.College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai 200090, China ;2.College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090, China
Abstract:
Fe-doped titanium dioxide (Fe-TiO2) nanoparticle catalysts were prepared by the sol-gel method, and their morphological structures, compositions and properties were characterized by XRD(X-ray diffraction), SEM(scanning electronic microscopy), EDX(energy dispersive X-ray spectroscopy) and UV-Vis spectrophotometry. Fe-TiO2 nanoparticles were used to remove gaseous elemental mercury under UV light and visible light respectively, and the optimum doping content of Fe3+ was determined. The results showed that Fe-TiO2 nanoparticles are an anatase, and that when the doping mole ratio of Fe/Ti was 0.010, the Fe-TiO2 catalyst had the highest Hg0 removal ability under both UV light (removal efficiency 54.76%) and visible light (removal efficiency 18.92%). The probable mechanism by which Fe-TiO2 nanoparticles remove gaseous elemental mercury was proposed:Fe3+ ions doped into the TiO2 structure may overlap the conduction bands of TiO2 and the d orbital of Fe3+, which results in the narrowing of the band gap and the extension of the visible light response. Fe3+ in TiO2 was a shallow trap, so after Fe3+ captured the photo-generated electrons, the photo-generated holes could continue to spread to the surface of TiO2 and accomplish surface chemical reactions, which produced reactive oxidative radicals O-2 and ·OH for the oxidation of Hg0. When Fe3+ doping molar concentration exceeded 0.010, the excessive Fe3+ became the trapping position of photo-generated electrons and photo-generated holes, increasing the probability of recombination of trapped electron-hole pairs via the quantum tunneling effect. Accompanied with the self-consumption of excessive reactive oxidative radicals O2- and ·OH, the photocatalytic efficiency was accordingly reduced. This is the mechanism by which there existed an optimum Fe/Ti doping molar ratio. The results provide some help for exploring ion modified method of TiO2 and its application in the visible light photocatalytic field.
Key words:  Fe3+-doped  titanium dioxide  sol-gel  photocatalysis  mercury  visible light response