Brain-like cobalt manganese oxide nano-composites coated on glass surface for enhanced photocatalytic degradation of Black Nilusun: effect of precursors on properties

Abstract

Brain-like cobalt manganese oxide nano-composites were effectively synthesized using co-precipitation processes. The effects of nitrate, sulfate and acetate of Co and Mn as precursors on structural, optical, thermal and morphological properties of cobalt manganese oxide nano-composites solid were studied by means of thermal analyses (TG–DTG), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy. The XRD results showed that the average particle size of cobalt manganese oxide nano-composites prepared from nitrate (MnCoNC-1), sulphate (MnCoNC-2) and acetate (MnCoNC-3) precursors were found to be 9, 12 and 13 nm respectively with MnCo2O4 and MnCo2O4.5 phases. The synthesised nanocomposites composed of spheres with brain-like structure are seen from FESEM results. The incorporation of cobalt into the manganese oxide structure is revealed by the distinctive FTIR transitions of Co–O–Mn vibrations. The characteristic band-gap energies of the different composites are estimated to be between 3.0 and 5.1 eV from UV reflection (DRS) spectra. Cobalt manganese oxide nano-composites coated on glass can effectively mineralize 92 % of azo textile dye within 3 h irradiation. The distinct properties and remarkable photocatalytical activities suggest the brain-type cobalt manganese oxide nano-composites are a promising material for enhanced photocatalytic degradation of Black Nilusun. The excellent photocatalytic activity may be due to the enhanced photo-induced charge separation brought on by the formation of coupling of two oxides in composite.