Facile synthesis of polypyrrole encapsulated V2O5 nanohybrids for visible light driven green sonophotocatalytic degradation of antibiotics

The present work reports for the first time ultrasound-assisted facile synthesis of stable polypyrrole/vanadium oxide (Ppy/V2O5) nanohybrids using various loadings of the conducting polymer. Infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) investigations confirmed the formation of the nanohybrids via synergistic interaction between C of Ppy with O of V2O5. The loading of Ppy in the nanohybrids was found to be 15%, 30% and 45% respectively which was confirmed by thermogravimetric analysis (TGA) and scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX) analyses. High resolution transmission electron microscopy (HR-TEM) revealed the formation of nanorods of V2O5 and a mixed morphology of spheres and rods in case of Ppy/V2O5 nanohybrids. X-ray diffraction (XRD) showed crystalline morphology of the nanohybrids but upon increasing the loading of Ppy up to 45%, the layered morphology of V2O5 was partially distorted. The band gap of Ppy/V2O5 nanohybrids was calculated to be 2.17 eV, 2.16 eV, and 2.14 eV for Ppy/V2O5-15/85, Ppy/V2O5-30/70, and Ppy/V2O5-45/55 respectively from diffuse reflectance spectroscopy (DRS) studies. The surface area was determined by BET analysis and was found to be 25.91 m(2)/g, 43.67 m(2)/g, 53.51 m(2)/g for Ppy/V2O5-15/85, Ppy/V2O5-30/70 and Ppy/V2O5-45/55 respectively. Highly efficient visible-light driven photocatalysis of Ppy/V2O5 nanohybrids was demonstrated by achieving 72-76% degradation of the antibiotics - ciprofloxacin (CIP) and erythromycin (E-mycin) within 50 min. Radical trapping experiments validated that the photogenerated center dot OH and center dot O-2(-) radicals were the two main photoactive species responsible for photocatalytic degradation. A plausible mechanism of photocatalytic degradation using Ppy/V2O5 nanohybrids under visible light irradiation is also proposed. Ppy was found to act as visible-light photosensitizer which aided the transfer of electrons to the conduction band of V2O5. The degraded drug fragments were identified using liquid chromatography-mass spectrometry (LC-MS). (C) 2018 Elsevier B.V. All rights reserved.