Cost effective green synthesis of NiO nanostructures as highly efficient photocatalysts for degradation of organic dyes

Abstract

Here, the cost effective green synthesis of nickel oxide (NiO) nanostructures has been reported. The organic capping and/or reducing agents were obtained by extraction from wastes of three different vegetables (cauliflower, potatoes and peas). The extracts of cauliflower and peas peels gave nanowhiskers while the extract of potato peels gave nanorods of NiO, as confirmed by scanning electron microscopy. X-ray diffraction analyses demonstrated the nanocrystalline cubic phase of NiO in all the samples. However, crystallite size varied with the extract of vegetable waste used. Fourier transform infrared analysis helps in identifying different vibrations, particularly Ni–O stretching vibrations, and diffuse reflectance spectra analyses led to the establishment of bandgap energies. The resulting NiO nanostructures were tested for their efficiencies as photocatalysts for Methylene blue degradation. All the three samples have shown significant photocatalytic activities. The exploration in this study clearly demonstrates the very high photocatalytic activities of the synthesised NiO nanostructures, which can be used as competent agents for treatment of wastewater to remove toxic dyes.