Fabrication of the flower-like NiCo2O4 @ Ni(OH)2/NiOOH composites supported on nickel foam by the green solvent dimethyl sulfoxide with high performance in supercapacitor and hydrogen evolution reaction

Because of their low synthesis cost, large specific surface area, and good energy storage performance, microporous metal-based composites have been widely used in supercapacitors and the hydrogen evolution reaction (HER). Flower-like Ni foam@ (@, coating) NCo2O4@Ni(OH)2/NiOOH (NF@NCO@NOH) composites were synthesized through a simple solvent-controlled method and following an electrochemical deposition process. The as-synthesized composites benefit from high specific area, a hierarchical porous structure, and the synergistic effect of Ni and Co, showing a high area-specific capacitance of 23.75 F cm−2 at a continuous current of 5 mA cm−2. The assembled asymmetric supercapacitor exhibits an energy density of 125 Wh kg−1 at a power density of 6.24 kW kg−1. Furthermore, 84.1% of the capacity was retained after 10,000 cycles, suggesting the sample has excellent electrochemical stability. Moreover, an overpotential of 162 mV at a current density of 10 mA cm−2 and a Tafel slope of 95 mV dec−1 were obtained in the HER measurement, indicating that the as-synthesized flower-like electrode material possesses potential applications in the HER.