Kinetics of stearic acid destruction on TiO2 ‘self-cleaning’ films revisited

7Citations
Citations of this article
9Readers
Mendeley users who have this article in their library.

This article is free to access.

Abstract

The photocatalytic oxidation of stearic acid, SA, by O2 is a common test method used to assess the activity of new materials and underpins a standard test for self-cleaning activity. The kinetics of this process have been well-studied and are often interpreted using one of two simple models, which are revisited here in this overview. The first model is based on the common scenario of a SA layer on top of an all-photocatalyst layer which yields zero order kinetics, for which it is suggested that all the reaction sites are occupied by SA during the bulk of the photocatalytic process. An important, but rarely noted feature of this system is that the rate of SA removal depends directly upon the fraction of absorbed ultra-bandgap radiation, which suggests that the photocatalyst particles are extensively networked, thereby allowing the photogenerated electrons and holes to move rapidly and efficiently to the surface to effect the destruction of SA. The second kinetic model has been used to describe the first order kinetics of SA removal observed for mesoporous photocatalytic films comprised of isolated photocatalyst particles, in which the SA is inside (rather than on top) of the photocatalytic film, and is developed further here. It is shown that, contrary to previous reports, this model is not appropriate for porous photocatalytic films in which the particles are extensively networked, such as ones based on powders or sol–gel films, even though they too may exhibit decay kinetics where the order is > 0. The reason for the latter kinetics appears to be a distribution of reactivities through such films, i.e. high and low activity sites. Graphical abstract: [Figure not available: see fulltext.].

Cite

CITATION STYLE

APA

Alofi, S., O’Rourke, C., & Mills, A. (2022). Kinetics of stearic acid destruction on TiO2 ‘self-cleaning’ films revisited. Photochemical and Photobiological Sciences, 21(12), 2061–2069. https://doi.org/10.1007/s43630-022-00278-0

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free