Enhancing the photocatalytic properties of TiO2 by coupling with carbon nanotubes and supporting gold.
Enhancing the photocatalytic properties of TiO2 by coupling with carbon nanotubes and supporting gold.
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DOI：
10.1016/j.jhazmat.2012.07.050
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发表时间：
2012-10
影响因子：
13.6
通讯作者：
Huihu Wang;S. Dong;Ying Chang;J. Faria
中科院分区：
文献类型：
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作者：
Huihu Wang;S. Dong;Ying Chang;J. Faria
研究了纳米TiO2光催化剂、CNT-TiO2光催化剂、Au-TiO2光催化剂和Au-CNT-TiO2光催化剂对水中亚甲基蓝的光降解。用X射线衍射仪、透射电子显微镜、差示扫描量热仪、氮气吸附-脱附等温线、漫反射紫外可见光谱等手段对材料进行了表征。通过碳纳米管-二氧化钛复合催化剂的研究，发现碳纳米管起到了吸附和光敏剂的作用，提高了纳米二氧化钛的光催化活性。在不同碳纳米管重量比(0.2-20%)的碳纳米管-二氧化钛复合材料中，2%的碳纳米管-二氧化钛具有最好的光催化活性。当碳纳米管含量大于2%时，剩余的碳纳米管可能会吸收和散射光光子。结合复合材料中二氧化钛含量的减少，光催化活性降低。为了进一步提高2%CNT-TiO2光催化活性，采用沉积-沉淀法引入了0.25%~1%不同的Au负载量。0.25%Au-2%CNT-TiO2复合材料具有最高的光催化活性。活性的提高是由于Au的表面等离子体共振，使复合材料比2%的CNT-Ti02吸收了更多的光子，从而克服了过量添加CNT的缺点。另一方面，由于碳纳米管的引入提供了更高的吸附容量，0.25%Au-2%CNT-TiO2复合材料也表现出比0.25%Au-TiO2更高的活性。碳纳米管和Au同时加入比单独引入时具有更强的协同作用。
The photodegradation of methylene blue in aqueous solutions is studied using various photocatalysts, including neat TiO2, CNT–TiO2, Au–TiO2, and Au–CNT–TiO2composites MB. Materials were synthesized and extensively characterized by XRD, TEM, DRFIT spectroscopy, N2adsorption–desorption isotherms, as well as diffuse reflectance UV–vis spectroscopy. By using CNT–TiO2composite as catalysts, it was found that CNT act as adsorbent and photosensitizer to improve the photoactivity of neat TiO2. Among the CNT–TiO2composites with different CNT weight ratio (0.2–20%), the 2%CNT–TiO2shows the best photoactivity. When CNT content is larger than 2%, the surplus CNT may absorb and scatter light photons. Combined with the decrease of TiO2amount in composite, the photoactivity is reduced. To further improve the photoactivity of 2%CNT–TiO2, different Au loads varying from 0.25% to 1% were introduced by the deposition–precipitation method. The 0.25%Au–2%CNT–TiO2composite had the highest photoactivity. The increase in activity was explained by the surface plasmon resonance of Au that makes the composite to absorb more photons than the 2%CNT–TiO2, thus overcoming the disadvantages of surplus CNT addition. On the other hand, 0.25%Au–2%CNT–TiO2composite also presents higher activity than 0.25%Au–TiO2due to higher adsorption capacity provided by CNT introduction. The addition of CNT and Au simultaneously has a much stronger synergic role than when each of them is introduced individually.