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题名: The catalytic effects of copper ions on photo-oxidation in TiO2 suspensions: The role of superoxide radicals
作者: Du, Yikui2;  Goldstein, Sara1, 3;  Rabani, Joseph1, 3
关键词: Photocatalysis ;  Titanium dioxide ;  Copper ions ;  Superoxide radicals ;  Dismutation ;  Methanol ;  Formaldehyde
刊名: JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
发表日期: 2011-12-01
DOI: 10.1016/j.jphotochem.2011.07.004
卷: 225, 期:1, 页:1-7
收录类别: SCI
文章类型: Article
WOS标题词: Science & Technology ;  Physical Sciences
类目[WOS]: Chemistry, Physical
研究领域[WOS]: Chemistry
英文摘要: UV photolysis of aerated aqueous suspensions of TiO2 (Degussa P25) containing CH3OH at pH 8.5 produces HCHO. Addition of CuSO4 affects the rate of HCHO formation (R-HCHO) in two opposite ways. Below 2 mu M, R-HCHO increases with increasing [CuSO4] while at higher concentrations it slows down. The enhancement of R-HCHO at very low [CuSO4] is attributed to catalytic dismutation of O-2(center dot-) forming H2O2 and O-2. At higher [CuSO4], R-HCHO decrease is attributed to removal of mobile holes by copper. Square root dependency of HCHO yield on the absorbed light density is observed in the entire [CuSO4] range used. The square root dependency is generally attributed to competition between second-order electron-hole recombination and first-order trapping, although the lifetime of both electrons and holes is too short to enable their accumulation in the same nano-volume. It is shown here that the electron-hole recombination path involves reaction of the mobile holes with adsorbed O-2(center dot-). The experimental results provide indirect evidence that adsorbed O-2(center dot-) radical ions, which are produced via O-2 reaction with the TiO2 electrons, are important for the well known square root dependency. Unlike the mobile and trapped electrons, O-2(center dot-) has a relatively long lifetime and its accumulation in the nano-volume upon successive absorptions of photons is feasible. It is concluded that the reaction between the accumulated O-2(center dot-) and mobile holes is responsible for the square root law. The decrease of K-d, which has been suggested as a standard parameter for the nature of TiO2 by added Cu(II) implies an apparent improvement of the TiO2 quality as a photocatalyst. (C) 2011 Elsevier B.V. All rights reserved.
关键词[WOS]: PULSE RADIOLYTIC INVESTIGATIONS ;  TITANIUM-DIOXIDE ;  PHOTOCATALYTIC DEGRADATION ;  AQUEOUS-SOLUTIONS ;  PEROXY RADICALS ;  FORMALDEHYDE FORMATION ;  OXIDATIVE-DEGRADATION ;  NONIONIC SURFACTANTS ;  PHOTONIC EFFICIENCY ;  RAPID MEASUREMENT
语种: 英语
WOS记录号: WOS:000298026300001
Citation statistics: 
内容类型: 期刊论文
URI标识: http://cas-ir.dicp.ac.cn/handle/321008/142562
Appears in Collections:中国科学院大连化学物理研究所_期刊论文

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作者单位: 1.Hebrew Univ Jerusalem, Accelerator Lab, IL-91904 Jerusalem, Israel
2.Chinese Acad Sci, Natl Lab Mol Sci, State Key Lab Mol React Dynam, Inst Chem, Beijing 100190, Peoples R China
3.Hebrew Univ Jerusalem, Inst Chem, IL-91904 Jerusalem, Israel

Recommended Citation:
Du, Yikui,Goldstein, Sara,Rabani, Joseph. The catalytic effects of copper ions on photo-oxidation in TiO2 suspensions: The role of superoxide radicals[J]. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY,2011,225(1):1-7.
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