A highly efficient Ag-ZnO photocatalyst: Synthesis, properties, and mechanism
A highly efficient Ag-ZnO photocatalyst: Synthesis, properties, and mechanism
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DOI：
10.1021/jp802729a
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发表时间：
2008-09-04
影响因子：
3.7
通讯作者：
Pillai, Suresh C.
中科院分区：
文献类型：
--
作者：
Georgekutty, Reenamole;Seery, Michael K.;Pillai, Suresh C.
制备了具有高光催化活性的银修饰ZnO，并对银修饰的效果进行了研究。利用x射线衍射、傅里叶变换红外光谱、差示扫描量热法、BET比表面积、拉曼光谱、紫外-可见光谱和光致发光光谱对其结构和光学性质进行了表征。通过对有机染料罗丹明6G （R6G）的降解分析，研究了这些材料的光催化活性，发现3mol %银修饰ZnO在400℃下的降解率比未修饰ZnO高约4倍，比商品TiO2光催化剂Degussa P-25高约3倍。研究还发现，改性后的ZnO样品的光催化活性比未改性的样品高5倍。通过分析ZnO和银修饰ZnO在R6G存在（发光增强）和不存在（发光减弱）情况下的发光特性，研究了银对光催化活性的增强作用。我们将这些观察结果归因于价带空穴产生的程度以及银在没有R6G的情况下捕获传导带（CB）电子的作用。在R6G存在的情况下，染料保留了金属氧化物中的CB电子居群，从而保留并增强了发射强度。染料的敏化性能和银的扫电子能力共同构成了以这种方式利用光激发电子的界面电荷转移过程。
Highly photocatalytically active silver-modified ZnO has been prepared and the effect of silver modification was studied. The structural and optical properties were characterized by X-ray diffraction, Fourier transform IR, differential scanning calorimetry, BET surface area, Raman, UV-vis, and photoluminescence spectroscopy. The photocatalytic activity of these materials was studied by analyzing the degradation of an organic dye, rhodamine 6G (R6G), and it is found that 3 mol % silver-modified ZnO at 400 degrees C shows approximately four times higher rate of degradation than that of unmodified ZnO and a three times higher rate than that of commercial TiO2 photocatalyst Degussa P-25. It was also noted that the photocatalytic activity for the modified ZnO sample was five times higher than the unmodified sample using sunlight. The effect of silver in enhancing the photocatalytic activity has been studied by analyzing the emission properties of both ZnO and silver-modified ZnO in the presence (emission increases) and absence (emission decreases) of R6G. We attribute these observations to the extent of valence band hole production and the role of silver in trapping the conduction band (CB) electrons in the absence of R6G. In the presence of R6G, the dye preserves the CB electron population in the metal oxide, thus preserving and enhancing emission intensity. The sensitizing property of the dye and electron scavenging ability of silver together constitute to the interfacial charge transfer process in such a way to utilize the photoexcited electrons.