Zinc sulfide decorated graphene nanocomposites are synthesized by a facile solvothermal approach and the prepared composites are analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High Resolution Transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR), Ultraviolet visible spectroscopy (UV), Photoluminescence spectroscopy (PL) and Raman spectrum. Results show the effective reduction of graphene oxide (GO) to graphene and decoration of ZnS nanoparticles on graphene sheets. Towards supercapacitor applications, the electrochemical measurements of different electrodes are performed in 6 M KOH electrolyte. A series of composites with different loadings of graphene is synthesized and tested for its electrochemical properties. The specific capacitance of the electrodes are evaluated from cyclic voltammetry (CV) studies and a maximum specific capacitance of 197.1 F/g is achieved in ZnS/G-60 electrode (60 indicates the weight ratio of GO) at scan rate of 5 mV s-1. A capacitance retention of about 94.1% is observed even after 1000 cycles for ZnS/G-60 electrode, suggesting the long time cyclic stability of the composite electrode. Galvanostatic charge-discharge curves show the highly reversible process of ZnS/G-60 electrode. Electrochemical Impedance Spectrum (EIS) shows a high conductivity of composite electrode suggesting that the composites are good candidates for energy storage. © 2015 Elsevier Ltd.

Nirmala Grace A

Centre for Nanotechnology Research

Vellore Campus

Ramachandran R

Saranya M

Kollu P

Raghupathy B.P.C

Jeong S.K

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Electrochimica Acta

Pyrite FeS2 was synthesized through a simple, cost effective solvothermal method. NaOH was used in the synthesis, which plays a crucial role as a pH regulator. The formation of pyrite FeS2 was confirmed through XRD, Raman Spectroscopy and FTIR. SEM results showed the formation of octahedral shaped particles with slight truncated edges. Thermogravimetric Analysis was performed to determine the properties of the material. The electrochemical studies were performed with a three electrode system to explore its supercapacitive behavior using 1 M Na2SO4 and 3.5 M KOH aqueous electrolytes. The electrochemical tests indicated that pyrite FeS2 exhibits a specific capacitance of 260 F/g at 1 A/g with an energy density of 46.8 Wh/kg. The good capacitance and high energy density makes it suitable to be used as an efficient electrode material for supercapacitors. © 2018 Elsevier Ltd

Solvothermal synthesis and electrochemical properties of phase pure pyrite FeS2 for supercapacitor applications

A series of vanadium pentoxide (V2O5/G) nanocomposites with graphene and doped graphene was synthesized by a facile solvothermal route and the supercapacitor performance of the obtained materials were further examined. The various heteroatom doped graphene composites viz. B doped (V2O5/BG), N doped (V2O5/NG) and BN codoped graphene (V2O5/BNG) was analyzed systematically to understand the effect of the dopants and their electrochemical properties. The structural and morphology of the obtained nanocomposites were investigated by using X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Thermogravimetric Analysis (TGA), Transmission Electron Microscope (TEM) and Brunauer, Emmett and Teller (BET). The results showed that the prepared V2O5 nanoparticles are deposited uniformly on graphene sheets. The electrochemical behavior of the nanocomposites were further analyzed to understand its supercapacitance properties in KOH electrolyte. A maximum specific capacitance of 1032.6 F/g was observed for V2O5/NG at 1 mVs-1 scan rate. Galvanostatic charge/discharge curves showed an excellent cyclic stability with higher charge/discharge duration with an energy density of 185.86 Wh/Kg and a power density of 37.20 W/Kg respectively for V2O5/NG nanocomposite. The graphene moieties provide fast and smooth electron transfer between V2O5 materials, thus leading to higher electrode performance compared with V2O5. The doping of heteroatom on graphene has been proven to be an effective way to tailor the properties of graphene and render its potential use for supercapacitor electrodes. © 2018 Elsevier Ltd

Heteroatom doped graphene based hybrid electrode materials for supercapacitor applications

Nanocomposites of MnS anchored on graphene, nitrogen-doped graphene and boron-doped graphene have been prepared by a simple wet chemical process.

Fulltext

RSC Advances

MnS nanocomposites based on doped graphene: simple synthesis by a wet chemical route and improved electrochemical properties as an electrode material for supercapacitors

A simple chemical route was adopted for the preparation of graphene by chemical reduction route using sodium borohydride (NaBH4) as a reducing agent. A systematic study was done to show the effect of NaBH4 on the reduction and the obtained graphene samples were characterized using X-ray diffraction, Fourier transform spectroscopy, Raman spectroscopy, Atomic force microcopy and High resolution transmission electron microscopy. Better reduction of GO was observed at GO and NaBH4 ratio of 1:10 (denoted as SR1:10). Further, the investigation was emphasized to show the effect of the above GO to reductant ratio on its charge storage properties. Electrochemical measurements were carried out in 6M KOH electrolyte and the results show that the capacitance performance was increased in the order of GO&lt;SR1:8&lt;SR1:4&lt;SR1:12&lt;SR1:10. A high specific capacitance of 284.3F/g was observed for SR1:10 electrode at 5mV/s scan rate could be due to better electrical conductivity of sample. The ratio of GO and NaBH4 was optimized to 1:10 for high degree reduction of graphene, which has higher capacitance towards supercapacitor applications. © 2015 Elsevier Ltd.

Applied Energy

Effect of reducing agent on graphene synthesis and its influence on charge storage towards supercapacitor applications

Nanocomposites of Co3S4 grown on nitrogen-doped graphene (NG) (Co3S4-NG) have been prepared at various concentrations of NG. The supercapacitive behaviors of the developed nanocomposites were assessed with cyclic voltammetry and galvanostatic charge discharge techniques. The nanocomposites exhibit excellent capacitive behavior with a high specific capacitance of 2427F/g at 2mV/s in Co3S4-NG-7 composite (7 indicates the percentage weight ratio of NG). The superior electrochemical performances could be due to synergistic effects between Co3S4 and NG, high charge mobility and good flexibility of graphene structures. These results indicate that the developed hybrid materials are promising candidates for high performance energy applications. © 2014 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Electroanalysis

Facile Synthesis and Electrochemical Properties of Co3S4-Nitrogen-Doped Graphene Nanocomposites for Supercapacitor Applications

Co9S8/graphene nanocomposites (Co9S8/G) at various concentrations of graphene and Co9S8 were prepared and tested for its electrochemical behaviour for supercapacitors.

RSC Adv.

Co9S8 nanoflakes on graphene (Co9S8/G) nanocomposites for high performance supercapacitors

Cobalt sulfide (CoS) and graphene nanocomposites were prepared from cobalt nitrate, thioacetamide, and graphene as starting materials in the presence of poly(vinylpyrrolidone) as surfactant. Furthermore, its morphology and properties were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope, diffusive reflectance ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and electrochemical measurements. The XRD reveals the amorphous nature of the nanocomposites. The as-prepared nanocomposites were tested for its supercapacitance property by cyclic voltammetric (CV) experiment in 6M KOH electrolyte. CV was performed at a potential range of 0 to-0.8 V at different scan rates, and results show an excellent capacitive behavior of the nanocomposites. A maximum specific capacitance of 2423.3 F/g was obtained at a scan rate of 5 mV/s. © 2013 IEEE.

IEEE Transactions on Nanotechnology

Synthesis of Cobalt Sulfide–Graphene (CoS/G) Nanocomposites for Supercapacitor Applications

Graphene platelets were synthesized from graphene oxide by chemical and electrochemical route. Under the chemical method, sodium borohydride and hydrazine chloride were used as reductants to produce graphene. In this paper, a novel and cost effective electrochemical method, which can simplify the process of reduction on a larger scale, is demonstrated. The electrochemical method proposed in this paper produces graphene in powder form with good yield. The atomic force microscopic images confirmed that the graphene samples prepared by all the routes have multilayers of graphene. The electrochemical process provided a new route to make relatively larger area graphene sheets, which will have interest for further patterning applications. Attempt was made to quantify the quantum of reduction using cyclic voltammetry and choronopotentiometry techniques on reduced graphene samples. As a measure in reading the specific capacitance values, a maximum specific capacitance value of 265.3 F/g was obtained in sodium borohydride reduced graphene oxide. © 2013 Elsevier Ltd. All rights reserved.

Journal	Data powered by TypesetElectrochimica Acta
Publisher	Data powered by TypesetElsevier BV
ISSN	0013-4686
Open Access	0