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Photocatalytic degradation of low concentration formaldehyde and simultaneous elimination of ozone by-product using palladium modified TiO2 films under UV254+185nm irradiation

Paper ID Volume ID Publish Year Pages File Format Full-Text
46811 46449 2011 9 PDF Available
Title
Photocatalytic degradation of low concentration formaldehyde and simultaneous elimination of ozone by-product using palladium modified TiO2 films under UV254+185nm irradiation
Abstract

Simultaneous elimination of formaldehyde and O3 by-product was investigated in the UV254+185nm photocatalysis with a continuous flow mode using palladium modified TiO2 films (Pd-TiO2). Formaldehyde (HCHO) was introduced at a low concentration (ca. 450 ppbv), typical of polluted indoor environments. Pd nanoparticles, deposited via an electrostatic self-assembly method, had uniform distribution on TiO2 films with an average size of 3–4 nm. Under UV254+185nm irradiation, the steady state concentration of HCHO was reduced to 10–50 ppbv for a long irradiation period (>30 h), and catalyst deactivation was not observed. Modification of TiO2 with palladium could simultaneously increase the conversion of HCHO and O3, especially at the high RH level, showing the excellent moisture-resistant behaviors. At the Pd loading of 0.3–0.4 μg cm−2, the O3 conversion ratio increased over 3 times compared to pure TiO2. XPS analysis exhibited that PdO on the TiO2 was oxidized to mixture palladium oxides PdOx(x > 1) under UV254+185nm irradiation. Due to high electron affinity of formed PdO2, the photogenerated electrons could be trapped by PdOx, thus improving the separation of e−/h+ pairs. As the reduction of PdO2 and oxidation of PdO coexisted, the PdOx could be dynamically stabilized, thus increasing the photoactivity of Pd-TiO2. Under UV254+185nm irradiation, the ozone might be decomposed on the Pd-TiO2 via two different routes, i.e., photocatalytic reduction of O3 on exposed TiO2 and decomposition of O3 on PdOx particles involved with UV irradiation and trapped electrons.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ultra-fine Pd nanoparticles are uniformly dispersed on TiO2 films. ► Formaldehyde can be rapidly degraded to a low level under UV254+185nm irradiation. ► Modification of TiO2 with palladium increases the removal rate of both formaldehyde and O3, with over 3 times improvement of O3 decomposition. ► The PdOx inhibit the recombination of e−/h+ pairs. ► Ozone can be decomposed on UV irradiated TiO2 and PdOx surfaces.

Keywords
Photocatalysis; Formaldehyde; Palladium modified TiO2; Ozone decomposition; Vacuum ultraviolet (VUV); Indoor air
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Photocatalytic degradation of low concentration formaldehyde and simultaneous elimination of ozone by-product using palladium modified TiO2 films under UV254+185nm irradiation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 105, Issues 1–2, 9 June 2011, Pages 220–228
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us