Hierarchically Porous Nanostructured Nickel Phosphide with Carbon Particles Embedded by Dielectric Barrier Discharge Plasma Deposition as a Binder-Free Electrode for Hybrid Supercapacitors

Three-dimensional (3D) metal phosphides are promising superior electrode components for supercapacitors. In this study, 3D porous nickel phosphide nanoarrays are successfully enrooted on the surface of nickel foam (Ni₂P/NF) by low-temperature hydrothermal treatment. Subsequently, a nanocarbon was embedded over Ni₂P@NF by efficient utilization of the environmental pollutant ethylene gas via a dielectric barrier discharge plasma reactor. This nanocarbon was deposited on porous Ni₂P/NF nanoarrays (Ni₂P-C/NF) as a positive electrode sandwiched with peanut shell-derived porous activated carbon (PNS-AC) as a negative electrode for the fabrication of a hybrid supercapacitor device. The hybrid supercapacitor device (Ni₂P-C/NF//PNS-AC) delivers an enormous amount of areal and gravimetric capacities values at a 1 A g^–1 current density of 318.8 μAh cm^–2 and 106.2 mAh g^–1, respectively. Moreover, the hybrid supercapacitor device achieved outstanding energy and power density with excellent cyclic durability (90.1%) even after 5000 cycles at 7 A g^–1, which are 108.1 Wh kg^–1 at 1 A g^–1 and 14,370.4 W kg^–1 at 15 A g^–1, respectively. These results evidenced that the novel nanostructured Ni₂P/NF with embedded carbon nanoparticles has excellent potential as the supercapacitor electrode material.