Visible light photocatalysis of methylene blue using cobalt substituted cubic NiO nanoparticles

This study reports the facile co-precipitation synthesis of pure and cobalt substituted NiO nanoparticles. The cubic crystalline structure of the synthesized NiO nanoparticles was confirmed through X-ray diffraction. Structural behaviour, morphological, elemental composition and optical properties of the prepared nanoparticles are investigated by Fourier transform infrared spectroscopy, scanning electron microscopy-energy dispersive spectrum, transmission electron microscopy and UV–Vis spectroscopy. The optical band gap is determined using UV spectra and is observed to decrease with an increase in cobalt ion concentration. Furthermore, methylene blue dye solution has been used to investigate the photocatalytic ability of the synthesized nanoparticles in the presence of sunlight. It is found that percentage degradation in dye concentration increases with irradiation time and also with the increase in the concentration of doping of cobalt in NiO. The dye solution is found to degrade to 94% within 50 min in the presence of solar radiation and the $$\hbox {Ni}_0.6\hbox {Co}_0.4\hbox {O}$$ sample.