Biosynthesis, Characterization of Nickel ‎‎(II) Oxide Nanoparticles NiO and their ‎High-Efficient Photocatalytic Application

This work sought to compare the photocatalytic efficiency of nickel (II) oxide nanoparticles (NiO-NPs) for the degradation of methylene blue (MB) and Rhodamine B dye (Rh B). NiO-NPs were synthesized by a green, simple and easy route using the plant extract H. Hirsuta. The morphological characteristics of the synthesized NiO NPs were characterized by SEM. In addition, UV-vis, XRD, FTIR and EDS analyses were also performed to investigate the optical properties, crystal size, functional groups and elemental composition of the NPs. These NiO NPs have a crystallinity size of 20.82 nm, and then were used for photocatalytic degradation of MB and Rh B in the presence of visible light irradiation.  The photocatalytic degradation rate under optimal conditions of MB and Rh B was found to be 97.19% and 79.42% , respectively. The kinetic study of photocatalytic degradation followed pseudo-first-order kinetics for MB and Rh B dyes. In addition, NiO-NPs were used for a 4-nitrophenol reduction activity reaching 91.17% for 3 cycles.