Abstract:
Flower-like ZnO architectures assembled with many nanorods were successfully synthesized
through Thermionic Vacuum Arc, operated both in direct current (DC-TVA) and a pulsed
mode (PTVA), and coupled with annealing in an oxygen atmosphere. The prepared coatings were
analysed by scanning-electron microscopy with energy-dispersive X-ray-spectroscopy (SEM-EDX),
X-ray-diffraction (XRD), and photoluminescence (PL) measurements. By simply modifying the TVA
operation mode, the morphology and uniformity of ZnO nanorods can be tuned. The photocatalytic
performance of synthesized nanostructured ZnO coatings was measured by the degradation of
methylene-blue (MB) dye and ciprofloxacin (Cipro) antibiotic. The ZnO (PTVA) showed enhancing
results regarding the photodegradation of target contaminants. About 96% of MB molecules were
removed within 60 min of UV irradiation, with a rate constant of 0.058 min1, which is almost nine
times higher than the value of ZnO (DC-TVA). As well, ZnO (PTVA) presented superior photocatalytic
activity towards the decomposition of Cipro, after 240 min of irradiation, yielding 96% degradation
efficiency. Moreover, the agar-well diffusion assay performance against both Gram-positive and
Gram-negative bacteria confirms the degradation of antibiotic molecules by the UV/ZnO (PTVA)
approach, without the formation of secondary hazardous products during the photocatalysis process.
Repeated cyclic usage of coatings revealed excellent reusability and operational stability.
