Insights into the generation of reactive oxygen species (ROS) over polythiophene/ZnIn2S4 based on different modification processing†
The performance of a polythiophene-modified ZnIn2S4 hybrid photocatalyst was associated with the processing methods. We reported the influence of different modification methods (blending versus surface polymerization) on photogenerated reactive oxygen species (ROS) and photocatalytic degradation of tetracycline. The photocatalytic degradation of tetracycline was enhanced with polythiophene modification either by blending or by surface chemical polymerization, and 51% or 54% NPOC (non-purgeable organic carbon) removal was achieved, respectively, in comparison with 36% for ZnIn2S4. Nanosized particles in the range of 10–20 nm were observed in pure ZnIn2S4 and the blended sample (PTh-ZIS) via an ethanol-thermal method, resulting in a high surface area of 188 m2 g−1 and 209 m2 g−1, respectively. The optical property of ZnIn2S4 still dominated the blended samples so that superoxide radical (˙O2−) was generated from ZnIn2S4 through electron transfer. For surface polymerization samples, transmission electron microscopy (TEM) clearly showed that ZnIn2S4 particles were covered by a thin polythiophene film, which can act as a photosensitizer promoting the generation of singlet oxygen (1O2) through energy transfer. Overall, our work revealed important processing guidelines together with ROS detection for the conductive polymer-modified photocatalyst.