Synthesis and characterization of NiO/Cr₂O₃ nanocomposite with effective sunlight driven photocatalytic degradation of organic dyes

In this paper, nanocomposite NiO/Cr₂O₃ has been synthesized by a simple chemical reduction method to study its photocatalytic activity under sunlight irradiation. Various advanced analytical techniques including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), elemental mapping, Fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopy have been utilized to characterize the synthesized NiO/Cr₂O₃ nanocomposite. SEM images show the sheet-shaped morphology of NiO/Cr₂O₃ nanocomposite. These sheets have a rough surface with nano to micro size cracks. These cracks play important role in the enhancement of photocatalytic activity by increasing surface active sites for the adsorption of dye molecules on the surface of the photocatalyst. The organic dyes crystal violet (CV) and methylene blue (MB) have been chosen to study the photocatalytic behavior of NiO/Cr₂O₃ nanocomposite under sunlight irradiation. The photocatalytic efficiency of NiO/Cr₂O₃ nanocomposite has been obtained 88.47% and 93.63% against crystal violet and methylene blue respectively. The results of the photocatalytic kinetics exhibit that degradation rate constant value for crystal violet dye is higher as compared to methylene blue dye. Obtained kinetic results indicate that synthesized nanocomposite acts as an efficient photocatalyst for the degradation of both crystal violet dye and methylene blue dye. NiO/Cr₂O₃ nanocomposite also exhibited reusability and stability for photocatalytic degradation of both organic dyes. Photoelectrochemical measurements as photocurrent, electrochemical impedance spectroscopy (EIS), and Mott-Schottky plot were also performed for synthesized NiO/Cr₂O₃ nanocomposite. Consequently, this synthesized NiO/Cr₂O₃ nanocomposite can be utilized for environmental remediation of harmful dyes.