期刊
APPLIED CATALYSIS B-ENVIRONMENTAL
卷 94, 期 1-2, 页码 142-149出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apcatb.2009.11.002
关键词
WO3; TiO2 nanotube arrays; Cr(VI); Photocatalytic reduction
资金
- National Science Foundation for Distinguished Young Scholars [50725825]
- National Basic Research Program of China [2009CB421601]
- Natural Science Foundation of Hunan Province, China [08JJ3113]
- National Science Foundation of China [50878079]
- Innovation Project in Postgraduation Education for Excellent Doctors [521218019]
Photoreduction of Cr(VI) was successfully achieved on WO3 doped TiO2 nanotube (NT) arrays in the presence of citric acid. WO3 doped TiO2 NT arrays were fabricated by annealing anodic titania NTs that were preloaded with peroxotungstic acid. Driven by electrostatic force, the negatively charged peroxotungstic acid sol uniformly clung to the positively charged titania NT arrays, causing a solid Solution of WO3 and TiO2 after annealing. The citric acid plays an important role in the photoreduction of Cr(VI): (i) it works as a sacrificial electron donor to deplete the photogenerated holes from the excited TiO2: and (ii) it takes part in the redox with Cr(VI) under UV illumination because of its electron rich property. The photochemical-reduction rate of Cr(VI) in citric acid under simulated solar light was 6.9 mu g/L min cm(2). Subtracting the part mentioned above, the reduction rate of Cr(VI) due to photogenerated electrons from excited photocatalysts increased from 8.3 mu g/L min cm(2) on TiO2 NTs to 31.6 mu g/L min cm(2) on WO3/TiO2 NTs containing 1 at% of W. The net Cr(VI) reduction rate on WO3/TiO2 NT arrays is 3.76 times that oh the unmodified TiO2 NTs. Since both WO3 and TiO2 can be excited by UV light, the enhanced photoactivity of WO3/TiO2 is attributed to the increased probability of charge-carrier separation and the extended photo-response spectrum in visible light region due to the doping of WO3 (band gap: 2.6 eV). (C) 2009 Elsevier B.V. All rights reserved.
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