Enhanced photocatalytic activity on Vanadium-doped NiO nanostructures in natural sunlight

The contamination of water from industrial pollutants is the most significant concern for environment. Semiconductors have been at forefront of effective elimination of pollutants from waste water, with the tuning of bandgap and improving the photocatalytic activity. This work elaborates the hydrothermal synthesize of highly stable Nickel Oxide (NiO) and Vanadium-doped Nickel Oxide (V-NiO) nanoparticles. The undoped and doped Nickel Oxide nanoparticles were characterized for structural, morphological, thermal and optical properties. X-ray diffraction pattern reveals the V-NiO stabilized in cubic structure. Morphological analysis demonstrates that upon Vanadium doping NiO particles transform from network like structure to spherical nanoparticles. NiO and V-NiO nanoparticles have an average crystallite size of 42 nm and 26 nm which are well matched with particle size calculated from transmission electron micrographs. The photoluminescence study reveals that the Vanadium substitution specifically reduces the rate of recombination in NiO. The V-NiO catalysts exhibited noticeable red shift of absorption spectrum to the visible region in comparison with pure NiO. The functional groups were studied using Fourier Transform Infrared Spectroscopy (FTIR). The photocatalytic study by degradation of Xylenol Orange (XyO) under sunlight irradiation unveils that photocatalytic activity of NiO is enhanced on vanadium doping. Reaction kinetics investigation of XyO degradation revealed that the reaction obeys the pseudo-zero-order model with improved rate constant of 0.115 mol L−1S−1 and 0.225 mol L−1S−1 for NiO and V-NiO, respectively. The retention of high performance and structural stability of photocatalysts after four consecutive degradation cycles implies the reusability of the catalyst. Consequently, the V-NiO with high photocatalytic activity with improved cyclic stability is able to provide as a promising material in the field of environmental remediation.