6533b7d9fe1ef96bd126d578
RESEARCH PRODUCT
Influence of metallic silver and of platinum-silver bimetallic deposits on the photocatalytic activity of titania (anatase and rutile) in organic and aqueous media
Jean-marie HerrmannAntonino Sclafanisubject
AnataseChemistryGeneral Chemical EngineeringGeneral Physics and Astronomychemistry.chemical_elementGeneral ChemistryPhotochemistryCatalysisMetalRutilevisual_artPhotocatalysisvisual_art.visual_art_mediumDehydrogenationPlatinumBimetallic stripdescription
Abstract The influence of deposited silver upon the photocatalytic activity of titania in the rutile and anatase allotropic forms has been studied in three different reactions. The common feature found for these three reactions was an electron transfer from illuminated TiO 2 to silver particles. In the first reaction (platinum photodeposition). it has been shown that the initial presence of metallic silver orientates the localization of subsequent Pt photodeposits with, in particular, a 100% selectivity to Pt deposition on top of silver particles or agglomerates previously deposited on anatase. In the second reaction (2-propanol oxidation), Ag deposit was found beneficial for the activity of rutile and detrimental for that of anatase. For rutile which is less active, silver helps for the electron-hole pair dissociation. By contrast, for anatase, the negatively charged Ag particles preferentially attract photoholes and become recombination centers, thus decreasing the photocatalytic activity. For the third reaction (dehydrogenation of 2-propanol), Ag/TiO 2 catalysts were found very poorly active, as expected for a group I-B metal. However, in the additional presence of platinum deposits, Pt/Ag/TiO 2 catalysts are as active as their Pt/TiO 2 homologues, thus confirming that Pt is deposited on top of silver with good electronic contacts between both metals. The three photocatalytic reactions have common electronic processes based on the photoelectron generation on titania and the subsequent electron transfer to the metal (s).
year | journal | country | edition | language |
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1998-02-01 | Journal of Photochemistry and Photobiology A: Chemistry |