Binder-free electro-synthesis of highly ordered nickel oxide nanoparticles and its electrochemical performance

In this work, highly ordered nickel oxide nanoparticles were electrochemically synthesized on nickel foam (NiOx NPs/Ni foam) via the formation and subsequent heat treatment of nickel hydroxide. The synthesized NiOx NPs were characterized using Fourier transform infrared (ET-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) with elemental analysis and high resolution transmission electron microscopy (HR-TEM). The XRD results revealed the presence of two different oxide phases with high crystallinity. The synthesized NiOx NPs were highly ordered spherical morphology with average size of 7 nm, identified from the FE-SEM images. Further, the electrochemical performance of synthesized NiOx NPs/Ni foam was evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge discharge (GCD) methods. The calculated specific capacity of NiOx NPs/Ni foam was found to be 219 C/g (60.7 mAh/g) at scan rate of 5 mV/s. This present work implies that the electro-synthesized NiOx NPs/Ni foam as a good binder-free, highly stable battery-type material and it can be used as a positive electrode for hybrid-capacitors. (C)2018 Elsevier Ltd. All rights reserved.