Hydrothermal synthesis of nickel oxide nanoflowers as a blend of 1D and 2D morphologies for its improved OER activity and supercapacitance

The development of multifunctional, cost-effective electromaterials for supercapacitors and the oxygen evolution reaction (OER), as well as improving their functionality, are now a focus in energy conversion and storage. Herein, a novel morphology of NiO is developed composed of nanorods encapsulated with nanosheets by optimizing hydrothermal process. The sample shows a high specific capacitance of 296 F/g at a current density of 5 A/g. For device characterization, symmetric supercapacitor cell was fabricated with achievement of a promising capacity at 120 F/g, 5 A/g. A competitive energy density value of 17 Wh/kg at 2500 W/kg of power density is attained. Also, the sample exhibits an overpotential of 1.96 V (vs. Ag/AgCl) at a current density of 10 mA/cm² with a Tafel slope of 109.2 mV/dec. This work is useful for further investigation into the specific capacity and OER of NiO-based electrode materials.