Photocatalytic degradation of malachite green dye using NiAl2O4 and Co doped NiAl2O4 nanophotocatalysts prepared by simple one pot wet chemical synthetic route

Abstract

Novel metal oxides have been studied worldwide due to their potential uses in ecological refinement, particularly to eliminate organic impurities present in water. In this work, we report the preparation of Ni_1-xCo_xAl₂O_4-δ (where x=0, 0.05, 0.10, 0.15 and 0.20) nanoparticles by simple chemical precipitation route. The as-synthesized spinel particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), particle size analysis, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), UV-Vis Spectroscopy (UV) and Photo Luminescence (PL) Spectroscopy techniques. The XRD results affirmed the development of the cubic structure in all the samples. FT-IR confirmed the presence of the M-O bond. Particle characteristics statistics showed the existence of particles in the range of 36-741 nm range. SEM analysis strengthened the presence of various sized grains (nano and micron) in the samples. EDX analysis affirmed the existence of an appropriate amount of elements (Ni, Al, Co and O) in all the samples. The band gap of Co doped NiAl₂O₄ was in between 2.8 – 3.0 eV, which was in line with the reported data. The PL spectra exhibited a strong peak at around 450 nm in the samples. From UV studies, the λ_max was around 310 nm in all the prepared samples. The photoluminescent characteristics of the samples were confirmed by PL studies and their photoemission was found at 437 nm. Among the samples studied, the parent NiAl₂O₄ shows more efficiency in degrading the malachite green (MG) dye than other Co doped NiAl₂O₄photocatalysts under the irradiation of visible light at the wavelength of 616nm at normal temperature.