In situ synthesis of polypyrrole/Nd-doped ZnO nanocomposite with enhanced visible light photocatalytic performance for the degradation of organic dyes

Abstract

In water resources, organic dyes are known as poisonous substances. As a result, photocatalytic treatment of pollutants has been implemented to address water quality challenges. In the present study, nanocomposite of Nd-doped ZnO (ZnO:Nd) and polypyrrole (PPy) was synthesized via in-situ polymerization to enhance the photodegradation of Methyl orange (MO) and Methylene blue (MB). The formation of PPy/ZnO:Nd nanocomposite was confirmed using Fourier-transform infrared spectra (FTIR) and X-ray diffraction (XRD). The activation energy and thermal stability of prepared samples were investigated by Simultaneous Thermal Analysis (STA). X-ray photoelectron spectroscopy (XPS) demonstrated that Nd atoms were successfully doped into the ZnO crystal structure. Microstructure images of powders were captured using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). UV–vis spectroscopy was employed to examine optical properties, revealing that the band gap energies of pure ZnO decreased from 3.29 eV to 1.8 eV upon doping with Nd atoms and coupling with PPy as a conductive polymer. PPy/20%ZnO:Nd nanocomposite has the highest MO and MB degradation efficiency of all synthesized powders. Using the Langmuir-Hinshelwood model, the reaction rate constant (k) of PPy/ZnO:Nd was calculated to be approximately 8 times faster than ZnO nanoparticles. After 5 cycles, the stability of the fabricated nanocomposite under visible radiation showed a slight decrease in catalyst efficiency. Therefore, this novel PPy/ZnO:Nd nanocomposite is an eco-friendly candidate for wastewater remediation due to its effective photocatalytic performance under solar light illumination.