Novel effect of significant enhancement of gas-phase photocatalytic efficiency for nano ZnO
Novel effect of significant enhancement of gas-phase photocatalytic efficiency for nano ZnO
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DOI：
10.1016/j.cej.2012.10.004
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发表时间：
2012-12
影响因子：
15.1
通讯作者：
W. Xie;Yuanzhi Li;Wenqin Shi;Liang Zhao;Xiujian Zhao;P. Fang;Feng Zheng;Shao-jie Wang
中科院分区：
文献类型：
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作者：
W. Xie;Yuanzhi Li;Wenqin Shi;Liang Zhao;Xiujian Zhao;P. Fang;Feng Zheng;Shao-jie Wang
制备了纳米 ZnO 光催化剂，并通过 XRD、BET、TEM、光电流测量和正电子湮没光谱 (PAS) 进行了表征。研究发现，纳米ZnO光催化剂气相光催化氧化丙酮的光催化活性随着反应温度的升高而显着增加。纳米 ZnO 样品的温度依赖性光电流测量表明，光催化活性的显着增强归因于随着温度的升高光生电荷载流子的分离效率大大提高。这种增强很可能归因于电离杂质散射和位错散射的影响，以及纳米 ZnO 样品的电导率随温度升高而增加。 PAS结果表明纳米ZnO样品中存在单空位和空位簇等缺陷，这可能导致电离杂质散射和位错散射的温度效应。提高纳米ZnO光催化活性的新策略是通过将纳米ZnO涂覆在高压汞灯表面而无需使用额外的加热器，在该策略下纳米ZnO受到紫外线照射和汞灯热能的共激发，从而轻松实现了提高纳米ZnO光催化活性的新策略。在这种光热催化条件下，纳米ZnO对丙酮的气相光降解表现出优异的耐久性，这与纳米ZnO在液相光降解中的光不稳定性形成鲜明对比。
Nano ZnO photocatalysts were prepared and characterized with XRD, BET, TEM, photocurrent measurement, and positron annihilation spectroscopy (PAS). It has been found that the photocatalytic activity for the gas-phase photocatalytic oxidation of acetone on the nano ZnO photocatalysts significantly increases with increasing reaction temperature. Temperature-dependent photocurrent measurement of the nano ZnO samples reveals that the significant enhancement of photocatalytic activity is attributed to a great enhancement in the separation efficiency of photogenerated charge carriers with increasing temperature. This enhancement is most probably attributed to the effects of the ionized impurity scattering and dislocation scattering, and the increased conductivity of the nano ZnO samples with the elevation of temperature. The PAS result indicates the presence of defects such as monovacancies and vacancy clusters in the nano ZnO samples, which probably leads to the temperature effect of the ionized impurity scattering and dislocation scattering. The novel strategy of improving photocatalytic activity of nano ZnO is facilely realized by coating nano ZnO on the surface of a high-pressure Hg lamp without using additional heater, under which nano ZnO was co-excited by both UV irradiation and thermal energy from the Hg lamp. Under such photothermocatalytic condition, nano ZnO exhibits an excellent durability for the gas-phase photodegradation of acetone, which is in striking contrast to the photoinstability of nano ZnO in liquid-phase photodegradation.