Photocatalyst Activity Indicator Inks, <i>paii</i>s, for Assessing Self-Cleaning Films

ConspectusSemiconductor photocatalysis, usually referred to simply as “photocatalysis” is a relatively new and yet still growing subject area, which has led billion-dollar industry, mostly focused on the production of self-cleaning architectural materials, such glass, paint, tiles, fabric, plastic concrete. All materials need be tested for activity, but activity there are few appropriate tests; International Standards Organization, ISO, example, have at present only two, both slow largely ineffective most commercial products. The photocatalyst community in general, manufacturers photocatalytic products particular, fast, simple, easy use method assessing can also used demonstrate efficacy minutes, i.e., quantitative qualitative test.In this account we highlight our work indicator inks, paiis, address above via photocatalyzed reduction dye, resazurin, Rz, concomitant oxidation an organic, almost always glycerol. We describe early Rz ink showed that, when assess film measured rate change color directly proportional mineralization popular test pollutants stearic acid, SA, methylene blue, MB, by O2. show that photography, coupled with digital analysis, just effective much less expensive measuring exhibited paiis UV/vis spectrophotometry testing clear opaque samples laboratory situ. how activities UV Visible light absorbing powders thin films, highly colored samples. kinetics outlined, zero-order respect initial dye concentration thickness. basic features recently published Rz-ink based ISO assessment nonporous, flat films.Although best suited films moderate found examples other described higher or lower, activities, paints respectively. Examples been research over recent years given, their search suitable, visible alternative TiO2, compete latter terms cost, durability, stability, activity. Finally, novel, photocatalyst-based inks developed consequence works discussed briefly, including ones for, photodepositing metal conducting wires cleaning tarnished metals, indicating levels dose O2 concentration.