posted on 2024-03-14, 14:15authored byKinga Michalec, Bartosz Mozgawa, Anna Kusior, Piotr Pietrzyk, Zbigniew Sojka, Marta Radecka
In semiconductor-based
photocatalysis, one of the most significant
directions in future research is designing materials with improved
activity for the targeted photodegradation of organic contaminants.
However, obtaining such photocatalysts requires an in-depth mechanistic
understanding of the involved interfacial processes. In this framework,
a comprehensive knowledge of photocatalysts’ ability to produce
particular reactive oxygen species (ROS) and their interaction with
contaminants is particularly crucial. This work aims to examine how
the phase composition of SnO2/SnS2-based nanomaterials
(from bare SnO2 to SnS2) affects their ability
to generate various ROS and propose the corresponding photodegradation
mechanism. To this end, we combined three methods: scavenger tests,
electron paramagnetic resonance (EPR) spin trapping techniques, and
UV–vis nitro blue tetrazolium (NBT) assay. To demonstrate the
implications of different ROS involved in the photodegradation of
a particular substance, indigo carmine (IC) dye was chosen as a model
contaminant. The second purpose of this study was to reveal and explain
side effects that appear during tests with commonly applied scavengers.
The results demonstrate the possibility of tunable ROS generation
(from •OH through 1O2 to O2•–) in SnO2/SnS2-based photocatalysts and the crucial role of superoxide radicals
in the IC photodegradation. These findings were correlated with the
band diagrams to rationalize the mechanisms of ROS formation and IC
degradation. The applied experimental approach demonstrated the importance
of using multiple techniques to examine ROS generation processes and
elucidate their mechanistic roles.