TY  - JOUR
TI  - Recommendations for improving the experimental protocol for the determination of photocatalytic activity by nitric oxide oxidation measurements
AB  - The photocatalytic nitric oxide (NO) oxidation reaction is used as a standard diagnostic tool for photocatalytic activity ac- cording to the well-defined protocol described by ISO Standard 22197-1-2007. This protocol identifies the negative peak showing a $NO_x$ concentration drop during a gas flow switch from the calibration bypass to the reactor as adsorption of $NO_x$ on the surface. Evidence is provided for this first transient to be due to a dilution effect in the gas phase within the reactor. With proper models of residence time distribution analysis, this transient revealed the internal hydrodynamics and it can be used to determine the internal volumes of the system. The second transient occurs immediately after the light is switched on. The conversions strongly depend on the time constant of this transient. Controlled measurements of the effect of illumination intensity revealed that at higher light intensities the transient takes longer to reach steady state. The longer transient was attributed to the time needed to reach a thermal steady state of the hot spots gener- ated by the recombination of excess charge carriers. When the catalyst amount was investigated as a parameter, a saturation effect was observed. This saturation effect was correlated with the gas phase concentrations of $NO_x$ and moisture and their ratios to the available specific surface area. Hence, additional constraints with respect to the illumination intensity and catalyst amounts are recommended for accurate measurements of photocatalytic activity by NO oxidation.
AU  - undefined, Selin Ernam
AU  - Akgül, Zeynep Ece
AU  - Uner, Deniz
DO  - 10.55730/1300-0527.3612
PY  - 2023
JO  - Turkish Journal of Chemistry
VL  - 47
IS  - 5
SN  - 1300-0527
SP  - 1285
EP  - 1295
DB  - TRDizin
UR  - http://search/yayin/detay/1208497
ER  -