Highly enhanced photocatalytic oxidation of CO on titania deposited with Pt nanoparticles: kinetics and mechanism
Highly enhanced photocatalytic oxidation of CO on titania deposited with Pt nanoparticles: kinetics and mechanism
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DOI：
10.1016/s0926-3373(03)00162-0
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发表时间：
2003-10-31
影响因子：
22.1
通讯作者：
Choi, W
中科院分区：
文献类型：
--
作者：
Hwang, S;Lee, MC;Choi, W
研究了纳米铂沉积在二氧化钛颗粒上对气态CO光催化氧化的影响。铂被直接光沉积在涂有二氧化钛的玻璃板上，典型的铂负载量类似于3wt.%。在30-500ppmv浓度范围内，铂沉积在二氧化钛表面可以显著提高CO的光氧化速率，而裸露的二氧化钛样品的光氧化速率要慢得多。铂诱导增强的程度强烈地依赖于二氧化钛衬底的种类。对Degussa P25、ISK STS-01、Hombikat UV-100三种商品二氧化钛样品进行了镀铂处理，并比较了它们对CO氧化的光活性。其中，铂化Hombikat TiO2光催化活性最好。在O-2存在下，CO光转化为M的反应是定量的。光沉积铂的氧化态既有Pt-0又有(PtO)-O-II，以(PtO)-O-II为主。光催化CO氧化速率与铂在二氧化钛表面的沉积量密切相关。在没有O-2或存在N2O和H2O等替代氧化剂的情况下，CO光氧化受到强烈的抑制。在O-2存在下，水蒸气的加入对CO光氧化动力学影响不大。在铂/二氧化钛催化剂上，羟基自由基对CO的光氧化似乎没有明显的影响。CO光催化氧化的主要氧化剂似乎来自于吸附的O-2，在光照下生成的活性氧物种即使在黑暗中也能稳定地存活数分钟，并参与后续的光氧化反应。考察了铂负载量、二氧化钛包覆量、CO浓度、O2浓度、光照强度、添加剂和湿度等因素对光催化氧化动力学的影响。(C)2003 Elsevier Science B.V.保留所有权利。
The effects of nanosized Pt deposits on TiO2 particles on the photocatalytic oxidation of gaseous CO were investigated. Platinum was photodeposited directly on a TiO2-coated glass plate with a typical Pt loading of similar to3 wt.%. Platinum deposition on TiO2 greatly enhances the photooxidation rate of CO in the concentration range 30-500 ppmv, whereas naked TiO2 samples exhibit much slower oxidation rates. The degree of Pt-induced enhancement strongly depends on the kind of TiO2 substrate. Three commercial TiO2 samples (Degussa P25, ISK STS-01, Hombikat UV-100) were platinized and compared for their photoactivity of CO oxidation. Platinized Hombikat TiO2 shows the best activity among them. The photoconversion of CO to M is quantitative in the presence of O-2. The oxidation states of photodeposited Pt include both Pt-0 and (PtO)-O-II with the former species dominant. The photocatalytic CO oxidation rates and the amounts of Pt deposited on TiO2 surface show a close correlation. The CO photooxidation is strongly inhibited in the absence of O-2 or in the presence of alternative oxidants such as N2O and H2O. The addition of water vapor little affects the CO photooxidation kinetics in the presence of O-2. Hydroxyl radicals do not seem to play a significant role in CO photooxidation on Pt/TiO2. The main oxidants in CO photocatalytic oxidation seem to be produced from adsorbed O-2, The active oxygen species generated on illuminated Pt/TiO2 surface are stable enough to survive for several minutes even in a dark period, and take part in a successive photooxidation reaction. The photocatalytic oxidation kinetics was investigated in detail as a function of Pt loading, coated TiO2 mass, CO concentration, O-2 concentration, light intensity, additives, and humidity. (C) 2003 Elsevier Science B.V. All rights reserved.