Vertically oriented Ni₃S₂/RGO/Ni₃S₂ nanosheets on Ni foam for superior supercapacitors

Abstract

A unique sandwich structure of Ni 3 S 2 /RGO/Ni 3 S 2 consisting of Ni 3 S 2 nanosheets was designed and constructed on nickel foam (NF) by a one-step hydrothermal process.The lower Ni 3 S 2 layer was converted in-situ from the Ni foam substrate, while the upper Ni 3 S 2 layer with vertical nanosheets was resulted from Ni 2+ ions in the solution.This Ni 3 S 2 /RGO/Ni 3 S 2 /NF nanocomposite was directly utilized as supercapacitor electrode, which possesses a high areal mass loading of 5.2 mg cm -2 , and superior performance: a specific capacitance of up to 16.82 F cm −2 (i.e., 3234.62 F g −1 ) at a current density of 20 mA cm -2 (3.85 A g -1 ) and retention 90% of initial capacitance after 1,000 cycles at the high rate of 100 mA cm -2 (19.23 A g -1 ). crystal increase and thus the thickness increase. For comparison, when the temperature increases to 240°C, the nucleation number increase, and the Ni 3 S 2 nanoflakes primarily grow in longitudinal height rather than in thickness, as shown in shown in Fig.4a-4c. A high magnification SEM image of Fig. 4c is shown in Fig.4e, and an array structure consisting of of highly porous Ni 3 S 2 sheets is vertically packed on the top side of the RGO, which is transformed from the nickel ion in the solution, forming the upper Ni 3 S 2 layer. On the other hand, the RNS-210 composite (Fig. 4f) displays relatively loose and random nanosheets of Ni 3 S 2 that result from the surface nickel source of NF, which can be considered as the same structure of the lower layer of Ni 3 S 2 nanosheets in the NRNS-210 composite.an auxiliary oxidant for Ni. Furthermore, this in-situ redox reaction can be developed to build RGO/metal oxides composite on the active metal substrate Fig. 8 The performance of the NRNS-210 composite films as electrode materials in supercapacitors was evaluated using cyclic voltammetry (CV) and Electrochemical performances of NRNS compositeschronopotentiometry. Fig. 8a shows the CV curves of the NRNS-210 electrode in a 2

Nanostructured polycrystalline Ni3S2 as electrode material for lithium ion batteries

“…Figure 6(B) shows that the XPS S-2p spectrum consists of different peaks centred at∼162.2,∼163.2,∼163.8,∼164.6,∼165.7,∼168.8, and∼169.9 eV respectively. The XPS peaks centred at∼162.2,∼163.2 eV and∼163.7,∼164.6 eV are ascribed to S 2p 3/2 and S 2p 1/2 spin-orbit levels respectively and confirms the presence of S −2 in Ni 3 S 2 material [38][39][40]. The peak centred at∼163.2 eV corresponds to metal-sulphur (Ni-S) bonds while the peak centred at∼162.2 eV is ascribed to sulphur ions at low coordination numbers on the surface [41][42][43].…”

Self-supported phase-pure Ni3S2 sheet-on-rod nanoarrays with enhanced pseudocapacitive properties and high energy density

“…No peaks due to other phases can be identified, suggesting a high phase purity of the sample. The valence state of Ni element in the Ni 3 S 2 sample was investigated by X-ray photoelectron microscopy (XPS) and the two main peaks at 855.4 and 873.2 eV in Figure S2B can be assigned to Ni 2p 3/2 and Ni 2p 1/2 [20,21], respectively, with each accompanied by a single smaller satellite peak (marked as "sate" on the spectrum). Such satellite peaks are usually associated with a socalled "shake-up" process where electrons in the valence band are excited to higher energy states [22].…”

Synthesis of Hollow Nanospherical Cuprous Oxide Supported by Nitrogen‐Doped Reduced Graphene Oxide and Its Application to Enzyme‐Free Glucose Sensing

“…Figure presents the Raman spectra of Graphite, GO and N‐rGO. Two special peaks at ∼1350 cm ‐1 and ∼1580 cm ‐1 assigned to the D band and G band are observed in the Raman spectrum of rGO and N‐rGO . The D band (∼1350 cm −1 ), which is related to the SP 3 hybridization of C atoms, indicating that there are defects and wrinkles on the edge of the material, represents the disorder of the lattice.…”