Influence of magnetic fields on the morphology and pseudocapacitive properties of NiO on nickel foam

Abstract

Nanostructured nickel oxide (NiO) films have been successfully deposited on nickel foam by a simple magnetic-field-assisted hydrothermal method, followed by calcination in air. The NiO thin films consisted of uniformly hexagonal nanoplates when magnetic fields (0–12.6 mT) were applied through an electromagnetic coil. The magnetic field affected the size and growth direction of NiO nanoplates, as well as the electrochemical performance of the NiO nanomaterial. The magnetic-field-assisted NiO electrodes showed better electrochemical performance than the NiO electrode synthesized without a magnetic field. The optimal NiO electrode had a specific capacitance of 932.1 F g⁻¹ at 0.5 A g⁻¹, with a retention ratio of 91.9% at 2.0 A g⁻¹ over 1000 cycles. These results indicated that the magnetic-field-assisted method in the hydrothermal synthesis of NiO electrodes could be an economical and effective way to produce high-performance supercapacitors.