Effect of Ni²⁺ doping on chemocatalytic and supercapacitor performance of biosynthesized nanostructured CuO

The synthesis of metal oxide nanostructured materials derived from plant extract embraces the futuristic design of an eco friendly system by reducing the hazardous toxic chemicals. In the present work, copper oxide nanoparticles (CuO NPs) and Ni²⁺ doped (0.003, 0.006 and 0.009 M) CuO NPs were prepared by green method using Azadirachta indica (A. indica) leaf extract. The XRD pattern reveals that the synthesized CuO NPs exhibits monoclinic structure. Nanoflower like morphology is observed in FESEM and TEM analysis. The oxidation states of Cu (2p), Ni (2p) and O (1s) have been identified in XPS spectra. The weight loss and thermal effects were investigated in TG–DSC analysis. The green synthesized materials effectively degrade the hazardous water pollutants like methylene blue, methyl orange and eosin yellow. The pseudocapacitive properties of CuO and Ni doped CuO NPs have been investigated through cyclic voltammetry and galvanostatic charge–discharge (GCD) studies. The Ni doped (0.009 M) CuO NPs exhibited high specific capacitance of 511 F/g at a current density of 1 A/g, and good reversibility with cycling efficiency of 88% after 3000 GCD cycles for S4 electrode, suggesting its use as promising electrode material in supercapacitors.