Supercapacitor behaviour of cobalt-doped nickel oxide films

Ordered nanostructured cobalt-doped nickel oxide films were prepared on a conducting glass substrate via the sol–gel dip-coating method. X-ray diffraction analysis shows the films to be amorphous. Field-emission scanning electron microscope images showed well-defined, ordered grains with pores in between them. Supercapacitor behaviour was studied using cyclic voltammetry. A maximum specific capacitance of 1982?F/g at a scan rate of 5?mV/s with 1?M KOH was obtained for 5?wt% of cobalt-doped nickel oxide films. AC impedance analysis showed that the solution resistance was R _s?=?27?Ω and the charge transfer resistance R _ct?=?20?Ω.     

Electromechanical behaviour of nanoporous metallic glass

Understanding the electrical and mechanical behaviour of nanoporous materials is critical for their use in energy applications. A palladium-rich nanoporous film, 500 nm thick with pore size ranging from 10 to 50 nm, was obtained by electrochemical dealloying of a Ni–Pd–P–B metallic glass. Nanomechanical and electrical properties were measured simultaneously, as a function of depth, for the nanoporous structure as well as the unaltered metallic glass substrate. The elastic modulus for the nanoporous structure was found to be 22 GPa compared to 131 GPa for the metallic glass substrate. The ratio of moduli scales with the square of the relative density in agreement with linear elasticity models for cellular materials. The electrical resistivity of the nanoporous layer was found to be 2.2 times higher compared to the metallic glass substrate, which was attributed to the tortuosity of current path in cellular structures.