Graphene Oxide For High-performance Supercapacitors Research Articles

Introducing CuCo2S4 Nanoparticles on Reduced Graphene Oxide for High-Performance Supercapacitor.

In this work, a bimetallic sulfide-coupled graphene hybrid was designed and constructed for capacitive energy storage. The hybrid structure involved decorating copper-cobalt-sulfide (CuCo2S4) nanoparticles onto graphene layers, with the nanoparticles anchored within the graphene layers, forming a hybrid energy storage system. In this hybrid structure, rGO can work as the substrate and current collector to support the uniform distribution of the nanoparticles and provides efficient transportation of electrons into and out of the electrode. In the meantime, CuCo2S4-active materials are expected to offer an evident enhancement in electrochemical activities, due to the rich valence change provided by Cu and Co. Benefiting from the integrated structure of CuCo2S4 nanoparticles and highly conductive graphene substrates, the prepared CuCo2S4@rGO electrode exhibited a favorable capacitive performance in 1 M KOH. At 1 A g-1, CuCo2S4@rGO achieved a specific capacitance of 410 F g-1. The capacitance retention at 8 A g-1 was 70% of that observed at 1 A g-1, affirming the material's excellent rate capability. At the current density of 5 A g-1, the electrode underwent 10,000 charge-discharge cycles, retaining 98% of its initial capacity, which indicates minimal capacity decay and showcasing excellent cycling performance.

Morphology regulation of conductive metal-organic frameworks in situ grown on graphene oxide for high-performance supercapacitors.

In this work, nickel-catecholate (Ni-CAT) nanorods were in situ compounded on graphene oxide (GO) to form a composite Ni-CAT@GO (NCG) with a special "blanket-shape" structure, which was used as an electrode material for supercapacitors. The morphology of Ni-CATs in situ grown on GO was modulated by introducing various contents of GO. With increasing GO, the length of nanorods of Ni-CATs is obviously shortened, and the charge transfer resistance of NCG is significantly reduced as the GO content is relatively low while it increases with further addition of GO, because excessive GO in NCG results in smaller crystal sizes accompanied by smaller stacking pores. Both the over-long Ni-CAT nanorods and the smaller stacking pores can restrict the accessible surface areas for the electrolyte. Optimal nanorod sizes are crucial to achieve good electrochemical performance for electrode materials. Galvanostatic charge-discharge analysis of NCG electrodes shows that their capacity initially increases and then decreases with the addition of more and more GO, and Ni-CAT@GO-0.5 (NCG0.5) with minimal charge transfer resistance exhibits the best electrochemical performance. The results demonstrate that the NCG0.5 electrode with optimal morphology possesses an excellent capacitance of 563.8 F g-1 at 0.5 A g-1 and a good rate performance of 61.9% at 10 A g-1, indicating that Ni-CAT@GO is a new type of promising electrode material for supercapacitors based on conductive metal-organic frameworks.

Controllable synthesis of phenolic resin-based carbon aerogel templated by graphene oxide for high-performance supercapacitors

In this work, porous phenol formaldehyde carbon aerogel (PFCA) was facilely manufactured by using simple hydrothermal method and ambient pressure drying. The micromorphology, specific area and electrochemical characteristic of the produced carbon aerogel were examined with scanning electron microscopy, nitrogen adsorption-desorption tests, cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The effects of catalyst and phenol addition, and solvent type on the structure and property have been systematically studied. The results show that the PFCA has a three-dimensional "bead chain" network structure and the typical PFCA-7.5/8 sample exhibits high specific surface area of 759.02 m2 g−1. Moreover, the graphene oxide composited phenol formaldehyde carbon aerogel (GO/PFCA) presenting a lamellar structure was developed by using GO as template. The optimum PFCA-7.5/8 prepared with ethanol as solvent has the best electrochemical performance of 138.33 F g−1 at 5 mV s−1 in 6 M KOH electrolyte, which can be improved to 150.00 F g−1 for the GO/PFCA-3 sample.

Synergistic effect of bimetal (Zn/Ni)–organic framework/reduced graphene oxide for high-performance supercapacitor

Supercapacitors with the advantages of large capacitance, long cycle life and high energy density are prominent for innovation in energy storage components. Herein, Zn/Ni-MOF/rGO composites are successfully synthesized through a one-step solvothermal method. The MOF/rGO compounds exhibit mutually beneficial synergies in structure: rGO sheets prevent MOF microspheres from serious agglomeration, while MOF microspheres could be spacers for inhibiting the overlapping of rGO. When the mass of GO was 25 % of the mass of the metal salt, Zn/Ni-MOF microspheres are well-dispersed among cross-linked rGO sheets (GMOF-25). The GMOF-25 delivers a splendid specific capacitance of 1644 F/g at a current density of 1 A/g and acceptable stability (85.1 % of the capacitance retention rate after 3000 cycles). In addition, the GMOF-25//activated carbon asymmetric supercapacitor displays a high energy density of 47.4 Wh/kg at a power density of 825 W/kg. The synergistic effect has been proved to play a vital role in promoting the electrochemical performance of supercapacitors via XRD, Raman and FTIR. This work provides a research approach for the design and manufacture of high-performance supercapacitors.

MIL-101(Fe)-Attached Graphene Oxide for High-Performance Supercapacitors with Sound Stability in Acid Electrolyte

MIL-101(Fe)-Attached Graphene Oxide for High-Performance Supercapacitors with Sound Stability in Acid Electrolyte

Unusual graphite fluoride hydrolysis toward unconventional graphene oxide for high-performance supercapacitors and Li-ion batteries

Graphene oxide was universally acknowledged to be a very important precursor to prepare graphene or the relative derivatives, but it was criticized sharply due to its quite inferior electrical properties and many structural defects arising out of strong oxidation process. Non-oxidation synthetic strategy of graphene oxide was expected a good solution to mitigate the disadvantages. Inspired by this concept, we attained a totally new, well-defined graphene oxide, that is, G(C4)–OH, in which hydroxyl was the unique oxygen-containing group and the hexagonal honeycomb carbon lattice was less-defective, by successfully challenging the hydrolysis of ultra-inert, commercially-available graphite fluoride feedstock. An advantaged structure made G(C4)–OH greatly outperforming traditional graphene oxide both in fundamental electrical properties, such as conductivity, carrier mobility, and in electrochemical performances when applied in supercapacitors and lithium-ion batteries. As convenient as traditional graphene oxide, G(C4)–OH was pretty reactive to versatile electrophiles and allowed tremendous post-functionalization opportunities to customize graphene functions and orientate its applications.

Hierarchical 3D starfish-like Ni3S4–NiS on reduced graphene oxide for high-performance supercapacitors

In this research, Ni3S4–NiS with starfish morphology was synthesized with a simple hydrothermal method and then hybridized with reduced graphene oxide (rGO) as a material for high-performance supercapacitors. The crystal structure and morphology of the as-prepared materials were studied by X-ray diffraction spectroscopy and electron microscopy. Uniform distribution of Ni3S4–NiS on rGO was observed from electron microscopy images. The results showed that Ni3S4–NiS/rGO with a specific capacitance of 1578 Fg-1 and discharge time of 603 s at the current density of 0.5 Ag-1 has more capacity and stability relative to Ni3S4–NiS. The cyclic stability after 5000 cycles showed that the Ni3S4–NiS/rGO electrode is stable, and 91% of its corresponding initial capacitance retained at the end of 5000 cycles. The good results in capacitance and stability of this electrode can be regarded as an improvement for the development of highly efficient and economic supercapacitors for portable electronic devices.

Transition Metal Sulfides Hybridized with Reduced Graphene Oxide for High-Performance Supercapacitors

Transition Metal Sulfides Hybridized with Reduced Graphene Oxide for High-Performance Supercapacitors

Supramolecular-induced confining methylene blue in three-dimensional reduced graphene oxide for high-performance supercapacitors

Adding redox-active species into the electrolyte can supply extra capacitance to the carbon-based supercapacitors. However, the devices may suffer from serious self-discharge caused by the shuttling and intermixing of charged active species between the electrodes. Confining these active species in a solid-state electrode material is an effective strategy to avoid this. Inspired by this, we fabricate a three-dimensional reduced graphene oxide confined methylene blue composite via a supramolecular strategy, combined with a hydrothermal reduction and a freeze-drying process. Benefited from the porous and conductive structure of the product, the fast-reversible electrochemical reaction of methylene blue, and the spatial confinement effect of the methylene blue confined in reduced graphene oxide, the as-prepared product exhibits a high-rate capability (311 and 262 F g−1 at 1 and 20 A g−1, respectively) and an excellent cycle stability (96% capacitance retention after 10000 cycles) in a three-electrode system. Moreover, a solid-state symmetric supercapacitor device based on the as-prepared product delivers the maximum energy density of 8.2 Wh kg−1 and outstanding cycle stability. This supramolecular-induced confining active species in reduced graphene oxide strategy provides insight into the fabrication of other high-performance graphene-based pseudocapacitors.

Nanocomposites of Copper Sulphide and Graphene Oxide for High-Performance Supercapacitors

Supercapacitors or electrochemical capacitors are receiving greater interest because of their high-power density, long life, low maintenance, and safer operation. The low energy density of such devices needs to improve. In this work, copper sulfide (CuS), a cheap and environment-friendly compound, is used along with graphene oxide (GO) to provide high energy and power densities. CuS nanoparticles and its nanocomposites with GO was synthesized using a facile method for supercapacitor applications. For the synthesis of CuS, an appropriate amount of copper acetate was dissolved in a water-butanol solution for 30 minutes followed by the addition of thiourea. The final solution was then transferred into Teflon-lined stainless-steel autoclave and heated at 180oC for 24 hours. The resulting participate of CuS was recovered using a centrifuge, washed with DI water, and dried in air for 24 hours. A similar procedure was followed for the synthesis of CuS-GO nanocomposite with the addition of appropriate amount of GO in the water-butanol solution prior to the addition of copper acetate and thiourea. Phase purity of the synthesized materials was determined by using X-ray diffraction (XRD) studies. XRD patterns of CuS showed the peaks at 2θ angle of 10.38o, 28.42o, 28.88o, 32.48o, 33.18o, 46.54o, 48.28o, and 59.68o corresponding to (100), (101), (102), (006), (110), (108), (116) planes, respectively, which indicates the covellite CuS hexagonal structure [1,2]. There were no additional peaks found in the XRD pattern of CuS-GO composite, confirming the phase purity of the synthesized materials. TEM images revealed nano-scale morphology of the synthesized particles. The particle size of CuS and CuS/GO composite were found as 95.11 nm, and 64.70 nm, respectively. All the electrochemical measurements were conducted in standard three-electrode configuration, using a platinum wire as a counter electrode and Hg/HgO as a reference electrode. CuS and its composite with graphene oxide on nickel foam were used as working electrodes. All the electrochemical measurements were performed in 3M KOH solution. Electrochemical properties of the synthesized samples were investigated using cyclic voltammetry and galvanostatic charge-discharge studies. The specific capacitance was calculated from cyclic voltammogram, obtained at various scan rate between 10 - 300 mV/s. The specific capacitance of CuS and CuS-GO nanocomposite was found to be 400 and 600 F/g, respectively at a scan rate of 10 mV/s. The detailed results on synthesis, physical, and electrochemical characterization will be presented.

Plasma-Assisted Simultaneous Reduction and Nitrogen/Sulfur Codoping of Graphene Oxide for High-Performance Supercapacitors

Nitrogen and sulfur-codoped reduced graphene oxide (RGO) was prepared with the assistance of an environmentally benign and facile route using an inductive coupled plasma (ICP) source. This novel ga...

Hydrothermal synthesis of well-standing δ-MnO2 nanoplatelets on nitrogen-doped reduced graphene oxide for high-performance supercapacitor

Nanocomposites of well-standing δ-MnO2 nanoplatelets on nitrogen-doped reduced graphene oxide (δ-MnO2/NRGO) were synthesized via a simple hydrothermal method. Herein, p-phenylenediamine serves as the molecule for “anchoring” δ-MnO2 on graphene oxide, as well as the nitrogen source. Especially, graphene oxide was functionalized with p-phenylenediamine firstly, which was used as the substrate for growing of uniform MnO2 nanostructures. δ-MnO2/NRGO nanocomposites were characterized by Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray Diffraction, Fourier Transform Infrared Spectroscopy, and X-ray Photoelectron Spectroscopy. The electrochemical performance of the as-synthesized nanocomposites was investigated, which displayed excellent specific capacitance (299.5 F g−1 at 5 mV s−1), superior cycle stability (97.8% retention after 8000 cycles) and good energy density (24.2 Wh kg−1 with the power density at 242 W kg−1). The improvement is primarily attributed to the specific nanostructure, as well as the doping of nitrogen which provides more active sites and promotes charge transferring.

NiFe layered double hydroxide electrodeposited on Ni foam coated with reduced graphene oxide for high-performance supercapacitors

High-performance electrode materials consisting of intertwined caterpillar-like NiFe layered double hydroxide bridges coated on reduced graphene oxide modified Ni foam (NiFe LDHs/rGO/NF) were prepared via a facile two-step electrodeposition method. First, rGO was electrochemically coated onto NF at a constant potential of −1.2 V vs. SCE for 600 s. Then NiFe LDHs of different Ni to Fe ratios were electrodeposited onto the formed rGO/NF electrodes at −1.2 V vs. SCE for 10 s. Under optimized conditions, NiFe LDHs/rGO/NF composites displayed a high specific capacitance of 1462.5 F g−1 at a current density of 5 A g−1 and retained about 64.7% of the original capacitance after 2000 cycles. Furthermore, a flexible asymmetric supercapacitor was prepared using NiFe LDHs/rGO/NF as the cathode and mesoporous carbon (MC) coated on NF as the anode. The supercapacitor exhibited an energy density of 17.71 Wh kg−1 at a power density of 348.49 W kg−1. All of these findings suggest that the new electrodes developed in this work hold a potential application prospect in flexible energy storage devices.

Robust heterostructures of a bimetallic sodium–zinc metal–organic framework and reduced graphene oxide for high-performance supercapacitors

A robust 2D heterostructure of heterobimetallic Na/Zn-MOF and rGO can be a promising alternative electrode material for next generation supercapacitors.

Supermolecule polymerization derived porous nitrogen-doped reduced graphene oxide as a high-performance electrode material for supercapacitors

We report a supramolecular strategy to fabricate high-doping-leveled (10.5 at.%) porous nitrogen-doped reduced graphene oxide (P-NrGO) with outstanding electrochemical properties as electrode material for supercapacitors. The introduced supramolecular polymers melamine cyanurate (MC) acts a barrier to prevent the graphene sheets from restacking, and meanwhile functions as a soft template to create porous structure as well as nitrogen source for in-situ N-doping. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images show that the P-NrGO exhibits wrinkled and loose-packed thin layer structure with a large number of pores. X-ray photoelectron spectrometer (XPS) spectra demonstrate that pyridine and pyrrole-N was the main nitrogen bonding states, which were favorable for the improvements of supercapacitive performance. Attributed to the synergistic effects of the porous structure and the N-doping, the P-NrGO1 exhibits an increase of 56.5% in the specific capacitance (335 F g−1) when compared with the rGO (214 F g−1). In addition, the capacitance retention ratio reaches 94.3% after 10000 cycles, indicating the excellent electrochemical stability. The present work benefits the large-scale production of N-doped graphene oxide for high-performance supercapacitors.

Oxygen-Incorporated and Polyaniline-Intercalated 1T/2H Hybrid MoS2 Nanosheets Arrayed on Reduced Graphene Oxide for High-Performance Supercapacitors

This work synthesizes the hybrid 1T/2H phase MoS2 nanosheets array on reduced graphene oxide for high-performance supercapacitors under extreme environmental temperature via oxygen incorporation an...

A new route for the synthesis of polyaniline nanoarrays on graphene oxide for high-performance supercapacitors

A traditional approach is conducted for the preparation of polyaniline/graphene oxide (PANI/GO) nanostructures, where aniline monomer followed by ammonium persulfate (APS) were added to an acidic solution of graphene oxide (GO). Herein, we investigate a condition in which firstly GO is dispersed in acidic media containing APS. The aniline monomer is then added in order to the in-situ polymerization of aniline. An investigation is also carried out on the effect of the acid type including sulfuric acid (H2SO4), hydrogen chloride (HCl), perchloric acid (HClO4), and p-toluenesulfonic acid (PTSA) on the morphology and electrochemical behavior of resultant PANI/GO nanostructures. The characterizations reveal well-defined nanoarrays for PANI/GO-H2SO4 electrode with the highest porosity and specific surface area. This electrode exhibits a highest current density in cyclic voltammetry studies and the most specific capacitance (727 F g−1) in charge/discharge studies among other as-prepared electrodes. Utilizing this PANI/GO-H2SO4 nanocomposite as the electrodes in a symmetric configuration resulted in the development of devices with remarkable performance including a maximum energy density of 40 Wh kg−1 and a power density up to 15.3 kW kg−1 with an excellent cycle life (only 4.3% loss after 5000 cycles).

Facile synthesis of 2D nitrogen-containing porous carbon nanosheets induced by graphene oxide for high-performance supercapacitors

2D N-containing porous carbon nanosheets are prepared in the presence of GO as a structure-directing agent by a facile hydrothermal method.

Bimetallic CoNiSx nanocrystallites embedded in nitrogen-doped carbon anchored on reduced graphene oxide for high-performance supercapacitors.

Exploring high-performance and low-priced electrode materials for supercapacitors is important but remains challenging. In this work, a unique sandwich-like nanocomposite of reduced graphene oxide (rGO)-supported N-doped carbon embedded with ultrasmall CoNiSx nanocrystallites (rGO/CoNiSx/N-C nanocomposite) has been successfully designed and synthesized by a simple one-step carbonization/sulfurization treatment of the rGO/Co-Ni precursor. The intriguing structural/compositional/morphological advantages endow the as-synthesized rGO/CoNiSx/N-C nanocomposite with excellent electrochemical performance as an advanced electrode material for supercapacitors. Compared with the other two rGO/CoNiOx and rGO/CoNiSx nanocomposites, the rGO/CoNiSx/N-C nanocomposite exhibits much enhanced performance, including a high specific capacitance (1028.2 F g-1 at 1 A g-1), excellent rate capability (89.3% capacitance retention at 10 A g-1) and good cycling stability (93.6% capacitance retention over 2000 cycles). In addition, an asymmetric supercapacitor (ASC) device based on the rGO/CoNiSx/N-C nanocomposite as the cathode and activated carbon (AC) as the anode is also fabricated, which can deliver a high energy density of 32.9 W h kg-1 at a power density of 229.2 W kg-1 with desirable cycling stability. These electrochemical results evidently indicate the great potential of the sandwich-like rGO/CoNiSx/N-C nanocomposite for applications in high-performance supercapacitors.

One-pot hydrothermal synthesis of flower-like β-Ni(OH) 2 encapsulated by reduced graphene oxide for high-performance supercapacitors

Abstract Flower-like β-Ni(OH)2 encapsulated by flexible reduced graphene oxide (rGO) nanosheets have been synthesized by one-pot hydrothermal process and were used as Faradaic electrodes for supercapacitors. β-Ni(OH)2 microflowers whose particle sizes ranging from 1.7 to 2.5 μm were effectively encapsulated by flexible rGO nanosheets. Due to the efficient charge transfer and unimpeded ion transports, such β-Ni(OH)2/rGO composites can deliver ultrahigh specific capacity of 618 C g−1 at a current density of 3 A g−1 and maintain 276 C g−1 at 30 A g−1 in 6 M KOH electrolyte. Besides, the β-Ni(OH)2/rGO composite electrode exhibits outstanding cyclic stability. When tested at a current density of 10 A g−1, high capacity retention ratio up to 90% can be achieved for the composite electrode after 2000 cycles. The outstanding cycling stability can be mainly attributed to rGO-encapsulating structure that effectively prevent the descent of electrical conductivity for the entirety of the electrode during the cycle processes. The ultrahigh specific capacity together with superb cycle performance make such composite a prospective candidate in capacitive energy storage field.