Photodeposition of metals from inks and their application in photocatalysis

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Abstract

Films of Ag, Pt and Au nanoparticles are photodeposited onto a range of commercial TiO2 based photocatalytic materials, such as paint, tile, awning fabric and glass, as well as a TiO2 sol-gel film, using an aqueous ink containing a sacrificial electron donor, glycerol, and the appropriate metal salt. The photodeposited metal films appear to be comprised of a fine covering of nanoparticular metal islands distributed evenly across the surface of the TiO2 sol-gel film, with some large aggregated particles for Pt (106 nm) and Au (33 nm). The rate of deposition of Ag is particularly fast, since a 10 s exposure to 2 mW cm−2 UVA light produces a very noticeable colour change, which is ca. 60 times that of the other two metal-ion containing inks. When combined with a photomask, the metal inks are used to create finely detailed metal film images on the surfaces of a wide variety of different, mainly commercial, photocatalytic materials; a fine metal mesh photomask is used to make metal micro-patterns. When used to promote the photocatalysed oxidation of organic pollutants dissolved in aqueous solution, such as 4CP and MB, the enhancement in photocatalytic activity (compared to a plain TiO2 film) exhibited by a photodeposited Pt on TiO2 film is modest (16–35%), however, the enhancement is marked (234%) for the photocatalysed oxidation of CO to CO2. In contrast, the Au and Ag films appear to depress the inherent activity of the naked TiO2. The Pt/TiO2 film also enhances significantly the photocatalysed oxidation of a film of soot (179%) but not of stearic acid (−23%); the Ag and Au films appear to impede the former reaction. The Pt/TiO2 film exhibits the most significant enhancement in rate for the photocatalysed reduction of water to H2 by ethanol, i.e. 62 times that of the Ag/TiO2 film, which exhibits only a modest activity, which in turn is better than a naked TiO2 film which shows no activity. The potential of the metal (ion) inks to more easily make photodeposited metal films on semiconductor photocatalyst films is discussed briefly.
Original languageEnglish
Pages (from-to)91-100
Number of pages10
JournalCatalysis Today
Volume335
Early online date26 Sep 2018
DOIs
Publication statusPublished - 01 Sep 2019

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