Ultra-high supercapacitor performance of NiSRu@NiO nanocomposites on nickel foam electrodes

Herein, a novel supercapacitor electrode is presented, fabricated through a solvothermal followed by an electrodeposition process. Specifically, a NiO nano-layer was initially developed on a nickel foam (NF) substrate through the solvothermal method, followed by a two-step electrodeposition process employing nickel, sulfur, and ruthenium precursors. The as-prepared electrode (NiSRu@NiO) exhibited excellent specific capacitance values of 1000 Fg � 1 even at high current densities of 10 Ag -1, accompanied by excellent stability (98 %) after 3000 cycles. The high specific capacitance values can be attributed to the synergetic effect between the different counterparts of Ni, S, and Ru. This is clearly revealed via a thorough comparison of NiSRu@NiO electrodes with various monoor bi-metallic compositions involving the employed metals (Ni, S, Ru) and through a comparison with state-ofthe-art electrodes. Structural and morphological characterization was performed by X-ray diffraction (XRD), Xray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), and field emission scanning microscopy (FE -SEM). The supercapacitor performance of the as-prepared electrode was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge tests (GCD), electrochemical impedance spectroscopy (EIS), and cycling stability tests.