Photocatalytic activities enhanced for decompositions of organic compounds over metal-photodepositing titanium dioxide [An article from: Chemical Engineering Journal]

This digital document is a journal article from Chemical Engineering Journal, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Three kinds of metals (Pd, Cu, and Pt) have been photodeposited either individually or simultaneously on a transparent thin film of titanium dioxide (TiO"2) that covers the inside surface of a Pyrex glass tube and the photocatalytic activities of these preparations have been investigated based on the oxidative decompositions of 2,4-dinitrophenol (DNP), formaldehyde (HCHO), and trichloroethylene (TCE) dissolved in aqueous solutions. The initial rate of DNP decomposition by Pd/TiO"2 is 2.5 times higher than that by TiO"2. Similarly, the initial rate of HCHO decomposition by Pd/TiO"2 is increased by 5.1 times. Such remarkable enhancements in the photocatalytic decompositions are also obtained with Pd-Cu/TiO"2 and Pd-Cu-Pt/TiO"2. Furthermore, Pd/TiO"2 is effective to promote the photocatalytic decomposition of TCE. This is different from the experimental result that was recently reported by other researchers, who used Pd/TiO"2 particles in the form of aqueous slurries. Microscopic observations of the metals deposited on the TiO"2 films reveal that the morphologies of the metal-photodepositing TiO"2 preparations are remarkably different from that of the TiO"2 film; each metal possesses its own coating pattern. A series of the photocatalytic reaction experiments indicate that the photocatalytic activities of the metal-depositing TiO"2 preparations are superior to that of the TiO"2 film and are highly stable.