NiO Nanoparticle Synthesis Using a Triblock Copolymer: Enhanced Magnetization and High Specific Capacitance of Electrodes Prepared from the Powder

Nickel oxide nanoparticles of diameter ∼21 nm were prepared by a sol-gel method using the triblock copolymer poly(ethylene glycol)-b-(propylene glycol)-b-(ethylene glycol). X-ray photoelectron spectroscopy analysis showed the presence of Ni²⁺ and Ni³⁺ ions in the material. The electrical conductivity of this material was due to small polaron hopping between Ni²⁺ and Ni³⁺ sites. The magnetization shown by these nanoparticles was much higher than that reported in the literature. This is ascribed to the presence of Ni³⁺ ions with uncompensated spin moments. Spin-glass behavior was exhibited by the material at 10.7 K. The electrochemical characterization of electrodes comprising of these NiO nanoparticles using cyclic voltammetric measurements showed a specific capacitance value of 810 F/g, the highest reported for this material. These materials will thus form one of the useful multifunctional systems.