One‐step synthesis of hierarchical structured nickel copper sulfide nanorods with improved electrochemical supercapacitor properties

Abstract

Summary Nanorods‐like structured ternary metal sulfides of Ni1‐xCuxS with various compositions (x = 0.1, 0.2 and 0.3), and binary sulfides of NiS and Cu9S5 were synthesised via a single‐step hydrothermal process. The structural properties and the functional groups of the synthesized materials were characterized by X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) studies. Surface structure and chemical composition of the samples were inspected using field emission scanning electron microscopy (FE‐SEM) and energy dispersive X‐ray spectroscopy (EDAX). The electrochemical properties of the as‐synthesised metal sulfide based electrodes were investigated by cyclic voltammetry (CV) and galvanostatic charge‐discharge (GCD) analyses and the maximum specific capacitance (SC) of ~1092 F/g was achieved for the Ni0.8Cu0.2S at a current density of 15 mA/g, while pure NiS and Cu9S5 electrodes showed the minimum SC of ~575 and ~70 F/g, respectively. Further, the electrochemical impedance studies (EIS) revealed low Rct value (3.4 Ω) for the Ni0.8Cu0.2S electrode and improved electrochemical supercapacitor properties of Ni0.8Cu0.2S electrode because of to the synergistic effect and its well crystalline nanorods structure which offers more electrochemical active sites for faradaic reactions and fast electrolyte ions diffusion in to electrode. Additionally, the stability performance of the Ni0.8Cu0.2S electrode was performed at a fixed current density of 20 mA/g, and the Ni0.8Cu0.2S sample possesses the good cycling stability with the retention of 80% capacitance after 3000 GCD cycles. These results demonstrate that the as‐synthesised binary and ternary metal sulfides are suitable cost effective and pollution free electrode materials for supercapacitors.

Hierarchical NiCo / NiO / NiCo 2 O 4 composite formation by solvothermal reaction as a potential electrode material for hydrogen evolutions and asymmetric supercapacitors

“…Interestingly, the slope of the straight line for NC2 and NC3 electrodes are larger than NC1 electrodes, demonstrating lower diffusion resistance and fast ion diffusion rate of electrolyte ions of NC1 electrode. 62,63 To further explore the practical application of prepared NC1 Ni/NiO/NiCo 2 O 4 composite structure, an asymmetric supercapacitor (ASC; NC1//AC) was fabricated in 6 M KOH electrolyte using NC1 and AC as the positive and negative electrodes, respectively. Figure 7A exhibits the individual CV curves of a positive and a negative electrode at a scan rate of 50 mV s À1 in a voltage range of 0 to 0.5 V and À1.0 to 0 V, respectively using a three-electrode system to match the mass of two electrodes.…”

1D interconnected porous binary transition metal phosphide nanowires for high performance hybrid supercapacitors

“…These results elucidate that the high capacitance of NCP is attributed to Faradaic redox reactions arising from abundant bimetallic redox sites. 31 The reversible redox reactions of the NCP can be expressed according to the following equations 17,19 :…”

“…27 Especially, 1D nanostructures have the advantages as follows: (i) short and fast charge transport pathway, (ii) high surface to volume ratio, (iii) excellent structural stability, (iv) facile access of ions to electroactive sites, and (v) inhibited volume change through the void space. [28][29][30][31] Therefore, the development of 1D nanostructured binary metallic NCPs is expected to enhance electrochemical performance.…”

Silver nanoparticles as a conductive bridge for high‐performance flexible all‐solid‐state asymmetric supercapacitor

“…However, the relatively lower energy density has limited their further practical application. Supercapacitors can be generally classified into two categories based on their mechanism of energy storage: pseudocapacitor and electrical double‐layer capacitors 6‐8 . Regardless of the energy storage mechanism, the energy of the supercapacitor is mostly stored near or at the interface of electrolyte and electrode 9‐11 .…”

“…Supercapacitors can be generally classified into two categories based on their mechanism of energy storage: pseudocapacitor and electrical double-layer capacitors. [6][7][8] Regardless of the energy storage mechanism, the energy of the supercapacitor is mostly stored near or at the interface of electrolyte and electrode. [9][10][11] Therefore, the characteristic of electrode materials is the key factor for the electrochemical properties of supercapacitor, especially the energy density.…”