Kinetics of reduction of a Resazurin-based photocatalytic activity ink

John MacKenzie, Grant MacDonald, Andrew Mills, Nathan Wells

Research output: Contribution to journalArticle

Abstract

The kinetics of reduction of a Resazurin, Rz,-based photocatalyst activity indicator ink, paii, on a commercial sample of self-cleaning glass, Activ™ is examined; the latter has ca. a 15nm compact coating of anatase TiO2 which serves as the active photocatalyst layer. The rate of dye reduction is reduced significantly by the presence of ambient O2. In the absence of O2, the measured change in film absorbance due to Rz, d Δ Abs/dt, was found to be independent of both [Rz] and film thickness, b. It is shown that this translates to the rate of dye reduction, d[Rz]/dt, being independent of the concentration of the Rz in the ink film, [Rz], and inversely proportional to film thickness, b. The observed kinetics are rationalised in terms of a kinetic model in which the rate determining step is the reduction of photocatalyst surface-adsorbed Rz by photo-generated surface electrons, with all photocatalyst surface sites occupied by Rz. Further work suggests that, if the kinetics of the photocatalysed reduction of the Rz paii were diffusion-controlled, then the decay in [Rz] would be first order and dependent upon b-2.
LanguageEnglish
JournalCatalysis Today
Publication statusAccepted/In press - 3 Jun 2016

Fingerprint

Ink
Photocatalysts
Thermodynamic properties
Kinetics
Film thickness
Coloring Agents
Dyes
Titanium dioxide
Cleaning
resazurin
Glass
Coatings
Electrons

Keywords

  • resazurin
  • resorufin
  • photocatalysis
  • kinetics
  • inks

Cite this

MacKenzie, John ; MacDonald, Grant ; Mills, Andrew ; Wells, Nathan . / Kinetics of reduction of a Resazurin-based photocatalytic activity ink. In: Catalysis Today. 2016.
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abstract = "The kinetics of reduction of a Resazurin, Rz,-based photocatalyst activity indicator ink, paii, on a commercial sample of self-cleaning glass, Activ™ is examined; the latter has ca. a 15nm compact coating of anatase TiO2 which serves as the active photocatalyst layer. The rate of dye reduction is reduced significantly by the presence of ambient O2. In the absence of O2, the measured change in film absorbance due to Rz, d Δ Abs/dt, was found to be independent of both [Rz] and film thickness, b. It is shown that this translates to the rate of dye reduction, d[Rz]/dt, being independent of the concentration of the Rz in the ink film, [Rz], and inversely proportional to film thickness, b. The observed kinetics are rationalised in terms of a kinetic model in which the rate determining step is the reduction of photocatalyst surface-adsorbed Rz by photo-generated surface electrons, with all photocatalyst surface sites occupied by Rz. Further work suggests that, if the kinetics of the photocatalysed reduction of the Rz paii were diffusion-controlled, then the decay in [Rz] would be first order and dependent upon b-2.",
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Kinetics of reduction of a Resazurin-based photocatalytic activity ink. / MacKenzie, John; MacDonald, Grant; Mills, Andrew; Wells, Nathan .

In: Catalysis Today, 03.06.2016.

Research output: Contribution to journalArticle

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AU - MacDonald, Grant

AU - Mills, Andrew

AU - Wells, Nathan

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