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Probing the activities of UV and visible-light absorbing photocatalyst powders using a resazurin-based photocatalyst activity indicator ink (Rz Paii)

Publication date:

1 April 2017

Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 338

Author(s): Andrew Mills, Nathan Wells, Christopher O’Rourke

A variety of semiconductor photocatalyst powdered materials, i.e. TiO2, CdS, WO3 and C3N4, are able to mediate the UV (365nm) photocatalysed reduction of Rz (blue) to Rf (pink) by glycerol, when used as a dispersion in deaerated, aqueous solution. Under the same conditions, but using visible (455nm) light, the same reaction is promoted by the visible-light absorbing semiconductors, CdS, WO3 and C3N4. These powders are mixed with SiO2 and PTFE powder and pressed as discs, for assessment using a Rz P hotocatalyst A ctivity I ndicator I nk, i.e. Rz paii, coated onto the surface of each disc. Results show that only the TiO2 pressed film, with UV irradiation, is able to photocatalyse the reduction of Rz to Rf, under ambient conditions, due to competition from ambient air. However, when covered with Sellotape™ to exclude O2, all but the C3N4 photocatalyst demonstrated photocatalytic activity, and in the same order as observed in solution for this reduction reaction, using UV or visible light. Irradiations carried out using 617nm light on the same systems reveal that the dye is slowly bleached, at a rate that this largely independent of the semiconductor/insulator present, and no Rf is generated, suggesting dye degradation via photolysis rather than dye sensitisation. This is the first example of the use of an Rz paii responding to visible light absorbing photocatalysts and the first example of an Rz paii being used to assess the photocatalytic activity of powdered SC photocatalysts.
Graphical abstract

Authors:   Author(s): Andrew Mills, Nathan Wells, Christopher O’Rourke
Journal:   Journal of Photochemistry and Photobiology A: Chemistry
Year:   2017
Publication date:   19-Feb-2017
Facts, background information, dossiers
  • light
  • reductions
  • solution
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