A critical review on reliability of quenching experiment in advanced oxidation processes

Mechanistic Insights into the Selective Oxidation of 5-Hydroxymethylfurfural over Au/TiO2 Catalysts under Photoexcited and Dark States

“…To identify the active species in the catalytic oxidation of HMF, different radical trapping reagents isopropanol (TBA) and edetate disodium (EDTA–Na 2 ) for • OH and h + , l -histidine ( l -His) for 1 O 2 and • OH, and p -benzoquinone (PBQ) for • O 2 – and 1 O 2 were adopted as scavengers. − The activities of the HMF oxidation reaction under visible light conditions and dark conditions were almost equivalent at 303 K. Therefore, in order to explore the difference between visible light and the dark state, the temperature of the radical quenching experiments was controlled at 273 K. As seen from Figures b,d, the activities had not changed significantly with the addition of isopropanol in both cases, indicating that • OH would not be the main dominant species in the catalytic oxidation of HMF to HMFCA in the dark conditions.…”

Tunable Generation of Reactive Oxygen Species in SnO2/SnS2 Nanostructures: Mechanistic Insights into Indigo Carmine Photodegradation

“…To this end, one of the most commonly applied methods is photocatalytic tests in the presence of substances called scavengers (quenching tests). 16,17 In these experiments, the higher inhibition of a photodegradation reaction indicates the more significant role of the investigated ROS (or photogenerated charge carriers). However, the observed quenching effect is affected by many factors, such as the concentration of a scavenger or its interaction with molecules present in the solution.…”

“…16−19 Consequently, scavenger tests can lead to misleading conclusions. 16,17 Therefore, to reliably investigate the photodegradation mechanism, it is crucial to combine these tests with other techniques, such as electron paramagnetic resonance (EPR) in conjunction with spin trapping or UV− vis/fluorescence spectroscopy (by using suitable chemical probes). 10,12,16,17 In this work, we have chosen to focus on SnO 2 /SnS 2 -based photocatalysts, heterostructures composed of wide (SnO 2 , E g = 3.5−3.8 eV 20−22 ) and narrow bandgap (SnS 2 , E g = 2.0−2.4 eV 23−26 ) semiconductors sharing the common tin(IV) cation.…”

“…16,17 Therefore, to reliably investigate the photodegradation mechanism, it is crucial to combine these tests with other techniques, such as electron paramagnetic resonance (EPR) in conjunction with spin trapping or UV− vis/fluorescence spectroscopy (by using suitable chemical probes). 10,12,16,17 In this work, we have chosen to focus on SnO 2 /SnS 2 -based photocatalysts, heterostructures composed of wide (SnO 2 , E g = 3.5−3.8 eV 20−22 ) and narrow bandgap (SnS 2 , E g = 2.0−2.4 eV 23−26 ) semiconductors sharing the common tin(IV) cation. By combining the properties of SnO 2 and SnS 2 , this system offers various advantages, such as an extended absorption range to visible light and an improved separation of photogenerated charge carriers.…”

“…The complexity of ROS generation pathways makes it vital to experimentally ascertain their presence in analyzed photocatalytic systems and, consequently, to elucidate the photodegradation mechanism. To this end, one of the most commonly applied methods is photocatalytic tests in the presence of substances called scavengers (quenching tests). , In these experiments, the higher inhibition of a photodegradation reaction indicates the more significant role of the investigated ROS (or photogenerated charge carriers). However, the observed quenching effect is affected by many factors, such as the concentration of a scavenger or its interaction with molecules present in the solution. − Consequently, scavenger tests can lead to misleading conclusions. , Therefore, to reliably investigate the photodegradation mechanism, it is crucial to combine these tests with other techniques, such as electron paramagnetic resonance (EPR) in conjunction with spin trapping or UV–vis/fluorescence spectroscopy (by using suitable chemical probes). ,,, …”