Synthesis and Characterization of Ternary α-Fe2O3/NiO/rGO Composite for High-Performance Supercapacitors (original) (raw)
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ChemistrySelect, 2019
was grafted on to the 2D rGO/h-BN by electroprecipitation method. Nitrogen of h-BN moiety and oxygen functional groups of rGO played the role of negative active site to trap the metallic cations. Electrochemical charge storage mechanism was optimized by controlling the stoichiometry and defect contents of Fe 3 O 4 /NiO@rGO/h-BN. Stoichiometry of the electro-precipitated samples was tailored in presence of negative active sites of rGO/h-BN and applied D.C. bias of the electrochemical bath. In addition, the nucleation and growth of metal oxides were influenced by the stacking and vacancy defects of rGO/h-BN sheets. High specific capacitance (1328 F g À 1) of Fe 3 O 4 /NiO@rGO/h-BN was attributed to the synergistic effect of electrochemical double layer capacitance of rGO, chemi-adsorption of-OH ions on Lewis acid (boron of h-BN moiety) and redox capacitance of Fe 3 O 4 /NiO in alkaline medium. In addition, the presence of pyrrolic defect at the rGO/h-BN stacking region acted as the nucleation site and provided additional redox capacitance by shifting the Fermi level towards the valance band. An asymmetric supercapacitor (ASC) was constructed using Fe 3 O 4 /NiO@rGO/h-BN and thermally reduced GO as positive and negative electrode, respectively. ASC showed high energy (82 W h Kg À 1) and power density (5600 W Kg À 1) along with low relaxation time constant (2.2 ms) and high stability (79%) after 10,000 charge discharge cycles.
Journal of Materials Science: Materials in Electronics, 2020
The reduced graphene oxide-Fe 2 O 3 (rGO-Fe 2 O 3) nanocomposites were synthesized by a facile and low-cost hydrothermal method employing rGO and Iron (III) nitrate precursors. The synthesis parameters including the reduction time and presence of reduction aid are studied. The structural and morphological studies of the nanocomposites were investigated by using Raman spectra, Fourier transform infrared spectroscopy, X-ray diffraction, and field emission scanning electron microscopy. The results indicate that Fe 2 O 3 nanoparticles with average particle size of 25 nm are well anchored on graphene sheets and the weight percent of the nanoparticles in the nanocomposites was influenced by the reduction time. The as-synthesized nanocomposites were characterized by a three-electrode system using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge in 1 M KOH aqueous solution. The electrodes made of rGO-Fe 2 O 3 nanocomposite synthesized by urea as reduction aid showed a high specific capacitance of 291 F g −1 at 1 A g −1 in the potential range of − 1 to 0 V. The best electrochemical performance of urea reducted rGO-Fe 2 O 3 nanocomposites is basically attributed to the effect of Fe 2 O 3 nanoparticles in preventing the restacking of rGO sheets.
A REVIEW ON ELECTROCHEMICAL SUPERCAPACITORS OF COMPOSITE-METAL-OXIDE NANOSTRUCTURES
In near future, use of electrochemical supercapacitors plays important role in energy and power storage applications which are broadly classified into two types; a) electrochemical-double layer capacitors, and b) redox capacitors. Favorable electrode materials used in electrochemical supercapacitors include transition metal oxides, conducting polymers, carbons and their composites etc. Now-a-days the aqueous and non-aqueous chemically grown metal oxide thin film electrodes including ruthenium oxide, iridium oxide, manganese oxide, cobalt oxide, nickel oxide, tin oxide, iron oxide, pervoskites, ferrites etc., have been envisaged for electrochemical supercapacitor application. This review presents a brief literature survey regarding electrode materials employed, so far, in electrochemical supercapacitors. Efforts have also been taken to highlight their configurations and charge transport/ collection kinetics.
The Enhanced Energy Density of rGO/TiO2 Based Nanocomposite as Electrode Material for Supercapacitor
Electronics
TiO2 electrode material is a poor choice for supercapacitor electrodes because it has low conductivity, poor cyclic stability, and a low capacitance value. It is inevitable to enhance electrode materials of this kind by increasing the surface area and combining high electronic conductivity materials. In the current research work, it was proposed to combine reduced graphene oxide (rGO) as it might provide a large surface area for intercalation and deintercalation, and also, it could establish the shorter paths to ion transfer, leading to a reduction in ionic resistance. The size, surface morphology, and crystalline structure of as-prepared rGO/TiO2 nanocomposites were studied using HRTEM, FESEM, and XRD, respectively. Using an electrochemical workstation, the capacitive behaviors of the rGO/TiO2 electrode materials were assessed with respect to scan rate and current density. The capacitances obtained through cyclic voltammetry and galvanostatic charge-discharge techniques were found ...
Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material
International Journal of Energy Research, 2020
The nanocomposite of NiO-ZnO/graphene oxide (GO) was synthesized for applications in supercapacitor electrodes material. GO was produced using the modified Hummers' method, and the nanocomposite of NiO-ZnO/GO was synthesized using the co-precipitation method. Thin films of nanocomposite powder were deposited on quartzite (glass) and fluorine-doped tin oxide substrates by a drop casting technique. X-ray diffraction revealed the crystallographic information of NiO-ZnO/GO nanocomposites. The surface morphology and elemental composition were studied using a scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The electrochemical properties were examined using cyclic voltammetry in a 1.0 M solution of Na 2 SO 4 electrolyte with a three-electrode system. Moreover, the NiO-ZnO/GO binary metal oxides nanocomposite based electrodes fabricated for supercapacitor delivered a high specific capacitance of 1690 F g −1 for 1:1/GO sample at a scan rate of 10 mV s −1 and has excellent conductivity due to reduced band gap energy range of 1.52-1.79 eV and with electrodes resistance of 0.02 Ω. The absence of semicircle in the Nyquist plot denotes low charge transfer resistance of the electrodes. The highest energy densities obtained for 1:1/GO and 2:1/ GO are 192 and 148 Wh kg −1 , respectively, while the highest power density obtained for 1:1/GO and 2:1/GO are 8.46 and 7.42 W kg −1 , respectively. Our study paves way for a facile, affordable, nontoxic, and fast way to synthesis binary transition metal oxides/GO-based electrodes material for highperformance supercapacitor.
Study of ternary metal oxides as supercapacitor electrodes
Energy and Sustainability V, 2014
Supercapacitors are energy storage devices that make use of ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudocapacitors). They complement batteries in electrical energy storage. Recent advances in charge storage mechanisms and the development of advanced nanostructured materials has yielded notable improvement in the performance of supercapacitors. The structural and electrochemical properties of the mixed metallic oxides Al x Cu y Co z Fe 2 O 4 (where x + y + z = 1) nanomaterials, which crystallise in a cubic spinel AFe 2 O 4 structure are investigated systematically with a gradual substitution of Al by transition metals. The crystal structure information studied by X-ray diffraction (XRD) depicts the formation of single phase spinel structure, while electron-dispersive X-ray spectroscopy (EDX) reveals the stoichiometric relations of Al, Cu and Co.
Synthesis of NiMoO4/3D-rGO Nanocomposite in Alkaline Environments for Supercapacitor Electrodes
Crystals
Although Graphene oxide (GO)-based materials is known as a favorable candidate for supercapacitors, its conductivity needs to be increased. Therefore, this study aimed to investigate the performance of GO-based supercapicitor with new methods. In this work, an ammonia solution has been used to remove the oxygen functional groups of GO. In addition, a facile precipitation method was performed to synthesis a NiMoO4/3D-rGO electrode with purpose of using synergistic effects of rGO conductivity properties as well as NiMoO4 pseudocapacitive behavior. The phase structure, chemical bands and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), Raman spectroscopy, and field emission secondary electron microscopy (FE-SEM). The electrochemical results showed that the NiMoO4/3D-rGO(II) electrode, where ammonia has been used during the synthesis, has a capacitive performance of 932 Fg−1. This is higher capacitance than NiMoO4/3D-rGO(I) without using ammonia. Furth...
Synthesis, properties, and performance of nanostructured metal oxides for supercapacitors
Pure and Applied Chemistry, 2014
Beyond activated carbon and other forms of high-surface area carbon operating solely as double layer storage materials in capacitors of high capacitance commonly somewhat imprecisely called supercapacitors other electrode materials storing electric charge by reversible and fast superficial redox processes are studied as active masses. The resulting devices combining double layer and Faradaic process-based charge storage – commonly called hybrid ones – show significantly higher capacitances at only marginally diminished power capability. Among the suggested materials metal oxides feature most prominently. Their formation, characterization and properties together with the performance of prepared devices are reviewed here.
Facile synthesis of NiTe2-Co2Te2@rGO nanocomposite for high-performance hybrid supercapacitor
Scientific Reports
The design of bimetallic tellurides that exhibit excellent electrochemical properties remains a huge challenge for high-performance supercapacitors. In the present study, tellurium is consolidated on CoNi2@rGO for the first time, to synthesize NiTe2-Co2Te2@rGO nanocomposite by using a facile hydrothermal method. As-prepared NiTe2-Co2Te2@rGO nanocomposite was characterized by EDS, TEM, FESEM, Raman, BET, XRD, and XPS techniques to prove the structural transformation. Upon the electrochemical characterization, NiTe2-Co2Te2@rGO has notably presented numerous active sites and enhanced contact sites with the electrolyte solution during the faradic reaction. The as-prepared nanocomposite reveals a specific capacity of 223.6 mAh g−1 in 1.0 M KOH at 1.0 A g-1. Besides, it could retain 89.3% stability after 3000 consecutive galvanostatic charge–discharge cycles at 1.0 A g−1 current density. The hybrid supercapacitor, fabricated by activated carbon as an anode site, and NiTe2-Co2Te2@rGO as a ...
Environmental Chemistry Letters
Supercapacitors are increasingly used for energy conversion and storage systems in sustainable nanotechnologies. Graphite is a conventional electrode utilized in Li-ion-based batteries, yet its specific capacitance of 372 mA h g−1 is not adequate for supercapacitor applications. Interest in supercapacitors is due to their high-energy capacity, storage for a shorter period and longer lifetime. This review compares the following materials used to fabricate supercapacitors: spinel ferrites, e.g., MFe2O4, MMoO4 and MCo2O4 where M denotes a transition metal ion; perovskite oxides; transition metals sulfides; carbon materials; and conducting polymers. The application window of perovskite can be controlled by cations in sublattice sites. Cations increase the specific capacitance because cations possess large orbital valence electrons which grow the oxygen vacancies. Electrodes made of transition metal sulfides, e.g., ZnCo2S4, display a high specific capacitance of 1269 F g−1, which is four...