TY - JOUR
T1 - A comprehensive aerosol spray method for the rapid photocatalytic grid area analysis of semiconductor photocatalyst thin films
AU - Mills, A.
PY - 2010
Y1 - 2010
N2 - Indicator inks, previously shown to be capable of rapidly assessing photocatalytic activity via a novel
photo-reductive mechanism, were simply applied via an aerosol spray onto commercially available pieces
of ActivTM self-cleaning glass. Ink layers could be applied with high evenness of spread, with as little deviation as 5% upon UV-visible spectroscopic assessment of 25 equally distributed positions over a 10cm×10cm glass cut. The inks were comprised of either a resazurin (Rz) or dichloroindophenol (DCIP) redox dye with a glycerol sacrificial electron donor in an aqueous hydroxyethyl cellulose (HEC) polymer media. The photo-reduction reaction under UVA light of a single spot was monitored by UV-vis spectroscopy and digital images attained from a flat-bed scanner in tandem for both inks. The photo-reduction
of Rz ink underwent a two-step kinetic process, whereby the blue redox dye was initially reduced to a pink
intermediate resorufin (Rf) and subsequently reduced to a bleached form of the dye. In contrast, a simple one-step kinetic process was observed for the reduction of the light blue redox dye DCIP to its bleached intermediates. Changes in red-green-blue colour extracted from digital images of the inks were inversely proportional to the changes seen at corresponding wavelengths via UV-visible absorption spectroscopy and wholly indicative of the reaction kinetics. The photocatalytic activity areas of cuts of ActivTM glass, 10cm×10cm in size, were assessed using both Rz and DCIP indicator inks evenly sprayed over the films;
firstly using UVA lamp light to activate the underlying ActivTM film (1.75mWcm−2) and secondly under
solar conditions (2.06±0.14mWcm−2). The photo-reduction reactions were monitored solely by flatbed
digital scanning. Red-green-blue values of a generated 14×14 grid (196 positions) that covered the
entire area of each film image were extracted using a custom-built program entitled RGB Extractor(C).
A homogenous degradation over the 196 positions analysed for both Rz (Red colour deviation = 19%
UVA, 8% Solar; Green colour deviation = 17% UVA, 12% Solar) and DCIP (Red colour deviation = 22% UVA,
16% Solar) inks was seen in both UVA and solar experiments, demonstrating the consistency of the selfcleaning
titania layer on ActivTM. The method presented provides a good solution for the high-throughput
photocatalytic screening of a number of homogenous photocatalytically active materials simultaneously
or numerous positions on a single film; both useful in assessing the homogeneity of a film or determining
the best combination of reaction components to produce the optimum performance photocatalytic film.
AB - Indicator inks, previously shown to be capable of rapidly assessing photocatalytic activity via a novel
photo-reductive mechanism, were simply applied via an aerosol spray onto commercially available pieces
of ActivTM self-cleaning glass. Ink layers could be applied with high evenness of spread, with as little deviation as 5% upon UV-visible spectroscopic assessment of 25 equally distributed positions over a 10cm×10cm glass cut. The inks were comprised of either a resazurin (Rz) or dichloroindophenol (DCIP) redox dye with a glycerol sacrificial electron donor in an aqueous hydroxyethyl cellulose (HEC) polymer media. The photo-reduction reaction under UVA light of a single spot was monitored by UV-vis spectroscopy and digital images attained from a flat-bed scanner in tandem for both inks. The photo-reduction
of Rz ink underwent a two-step kinetic process, whereby the blue redox dye was initially reduced to a pink
intermediate resorufin (Rf) and subsequently reduced to a bleached form of the dye. In contrast, a simple one-step kinetic process was observed for the reduction of the light blue redox dye DCIP to its bleached intermediates. Changes in red-green-blue colour extracted from digital images of the inks were inversely proportional to the changes seen at corresponding wavelengths via UV-visible absorption spectroscopy and wholly indicative of the reaction kinetics. The photocatalytic activity areas of cuts of ActivTM glass, 10cm×10cm in size, were assessed using both Rz and DCIP indicator inks evenly sprayed over the films;
firstly using UVA lamp light to activate the underlying ActivTM film (1.75mWcm−2) and secondly under
solar conditions (2.06±0.14mWcm−2). The photo-reduction reactions were monitored solely by flatbed
digital scanning. Red-green-blue values of a generated 14×14 grid (196 positions) that covered the
entire area of each film image were extracted using a custom-built program entitled RGB Extractor(C).
A homogenous degradation over the 196 positions analysed for both Rz (Red colour deviation = 19%
UVA, 8% Solar; Green colour deviation = 17% UVA, 12% Solar) and DCIP (Red colour deviation = 22% UVA,
16% Solar) inks was seen in both UVA and solar experiments, demonstrating the consistency of the selfcleaning
titania layer on ActivTM. The method presented provides a good solution for the high-throughput
photocatalytic screening of a number of homogenous photocatalytically active materials simultaneously
or numerous positions on a single film; both useful in assessing the homogeneity of a film or determining
the best combination of reaction components to produce the optimum performance photocatalytic film.
KW - photocatalysis area
KW - thin film
KW - aerosol
KW - mapping method
UR - http://www.scopus.com/inward/record.url?scp=77951623480&partnerID=8YFLogxK
UR - http://dx.doi.org/10.1016/j.aca.2010.01.022
U2 - 10.1016/j.aca.2010.01.022
DO - 10.1016/j.aca.2010.01.022
M3 - Article
SN - 0003-2670
VL - 663
SP - 69
EP - 76
JO - Analytica Chimica Acta
JF - Analytica Chimica Acta
ER -