Photocatalyst activity indicating adhesive labels for use in the field

Mills, Andrew; Hawthorne, D.; Hazafy, David; Wells, Nathan

doi:10.1016/j.jphotochem.2018.01.005

Cited by 4 publications

(2 citation statements)

References 32 publications

(45 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More recently this group has reported a screen-printed, nonreusable Rz label which is also suitable for the in situ assessment of photocatalytic films and was tested using samples of commercial photocatalytic glass, paint, tiles and awnings. 36…”

Section: A Mb Reusable Paii Labelmentioning

confidence: 99%

Photocatalyst Activity Indicator Inks, paiis, for Assessing Self-Cleaning Films

2021

View full text Add to dashboard Cite

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

show abstract

Section: A Mb Reusable Paii Labelmentioning

confidence: 99%

Photocatalyst Activity Indicator Inks, paiis, for Assessing Self-Cleaning Films

2021

View full text Add to dashboard Cite

show abstract

“…Rz-ink and closely related formulations with other dyes have since been adopted as testing technique in many studies. Examples of Rz, Acid Violet 7 and Basic Blue 66-ink formulation as assessment techniques for a variety of PhMs are included in [7]; Methylene Blue (MB), 2,6-DiChloroIndoPhenol and Resorufin for self-cleaning glass in [8]; and NitroBlueTetrazolium (NBT) on cement-based materials and emulsion coatings (ref). Further details about Rz and NBT-ink testing are discussed below in section 2.3.1.…”

Section: Introductionmentioning

confidence: 99%

Rapid assessment of the photocatalytic activity in construction materials: Pros and cons of reductive inks and oxidative fluorescence probes versus standardized NOx testing

Jiménez-Relinque

Castellote

2020

Catalysis Today

View full text Add to dashboard Cite

The photocatalytic activity of a wide variety of photocatalytic construction materials with different intrinsic properties, mainly microstructure and TiO2 crystallographic phases, were obtained using alternative methods (Rz and NBT-reductive inks and TA-oxidative fluorescence probe) and the NOx removal standard ISO 22197-1:2007. The Rz-ink test was shown to be unsuitable for some of the materials due to spontaneous colour change in the dye upon contact with these (here denominated) reactive samples, in the absence of radiation. No such shortcomings were observed for either NBT-ink or TA-probe. Comparison of the three set of results showed a reasonably high correlation among the activities determined by the different methods, despite the wide variation in the characteristics of the photocatalytic materials tested, underlying reaction mechanisms and the physics and chemistry of the inter-phase contact (ink/probe/contaminant-substrate). The findings attest to the possible relationship between the rates of oxidative and reductive reactions in semiconductor photocatalysis. These alternative methods may be regarded as a new 'cheap and simple' approach to photocatalytic activity measurements.

show abstract