A novel, hydrogel-supported photocatalyst activity indicator, Hpaii, is presented, based on an agar gel containing the pH indicator dye propyl red (PR), and the photoacid generator, diphenyliodonium nitrate (DPIN). The latter is broken down when the film is on an active photocatalytic film, and the acid released protonates the PR, turning the gel from a yellow colour to a red. Initially tested on a TiO2 sol-gel film, the Hpaii is also shown to be effective in indicating the activity of several different commercially available photocatalytic surfaces, including: glass, tiles and paint. This is the first example of a water-based photocatalyst activity indicator ink based on monitoring a photocatalytic process via the change in pH induced in the indicator films, as revealed by the pH-indicator, propyl red.
|Journal||Journal of Photochemistry and Photobiology A: Chemistry|
|Early online date||19 Jun 2017|
|Publication status||Published - 01 Sep 2017|