Polythiophene doped ZnO nanostructures synthesized by modified sol-gel and oxidative polymerization for efficient photodegradation of methylene blue and gemifloxacin antibiotic

Abstract

The present work aims to enhance the photocatalytic performance of mesoporous ZnO by doping with polythiophene (PTh) for the treatment of toxic pollutants. Polythiophene doped ZnO (PTh/ZnO) photocatalysts with various weight percentages of PTh (1–10%) were synthesized via modified sol-gel and oxidative polymerization techniques. The XRD patterns revealed a well-crystalline hexagonal wurtzite phase of ZnO, whereas the XPS, FTIR and Raman spectra confirmed the successful coupling between PTh and ZnO nanostructures. TEM results illustrate the uniform distribution of PTh onto the mesoporous ZnO. UV–vis spectroscopy revealed a small lowering in bandgap energies upon PTh incorporation. The prepared PTh/ZnO nanostructures have been successfully exploited for the photocatalytic degradation of methylene blue dye (MB) and gemifloxacin mesylate (GFM) antibiotic. All doped samples exhibited superior performances in comparison to either pure PTh or undoped ZnO. The 5% PTh/ZnO showed the highest activity with 95 % degradation efficiency of MB dye in 180 min of irradiation with rate constant value 0.0156 min−1 which is almost 2.6 higher than pure ZnO. In addition to this, 5% PTh/ZnO proven to be highly active towards the degradation of gemifloxacin mesylate antibiotic after 180 min of irradiation time, yielding ∼80 % degradation efficiency. Repeated cyclic use of the current photocatalyst indicated excellent reusability and operational stability. The reaction mechanism involved during the photocatalytic degradation is also proposed.