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Benefiting from good ion accessibility and high electrical conductivity, graphene-based material as electrodes show promising electrochemical performance in energy storage systems. Well-dispersed and homogeneous Mn 3 O 4 nanosheets are grown on graphene layers through a facile chemical co-precipitation process and subsequent flame procedure. Supercapacitors have attracted much attention owing to their robust lifetimes, rapid charging capabilities and high power energy storage for mobile phone, hybrid electrical vehicles, back-up power systems, cranes, and lift [ 12345 ].
A promising supercapacitor stores much more energy compared with electrostatic and electrolytic capacitors and exhibits stronger power with longer cycle life than the available battery [ 67 ]. Compared with a great mass of mercantile supercapacitor electrode, 108655 metal oxides used as supercapacitor electrode have high energy density, good capacitive performance and long cycle stability [ 89 ].
This drawback can be overcome by using hybrid materials via coupling of conductive materials and MnO x [ 1213 ]. Combining well-aligned nanocrystalline structures and two-dimensional 2D graphene sheet with enhanced electron transport, ultrahigh exposed surface area and improved mechanical stability are lek interesting [ 1415161718 ].
The composite delivers a volumetric energy density of 0. Wang and co-workers reported an ASC was assembled by graphene MnO 2 nanosheet hybrid materials as the positive electrode and porous graphene as the negative electrode, respectively.
Graphene MnO 2 was prepared by polyaniline-assisted anchoring MnO 2 ultrathin nanosheet and lie on the graphene substrate. The composite was used as an electrode show excellent specific capacitance of Furthermore, the assembled ASC achieved a promising energy density of 7. Octylamine as surfactant, graphene sheets as substrate and manganese carbonyl Mn 2 CO 10 as precursor are prepared Mn 3 O 4 nanodot composites anchored on nitrogen-doped graphene sheet Mn 3 O 4 NDs NG.
Oei results of these studies demonstrated the beneficial role of rGO and the significance of synergistic effects.
Graphene is found as the thinnest two-dimensional and its basic structure unit is benzene six-membered ring. It is just a one carbon atom thick and honeycomb-like sheet showing lots of particular physical chemistry properties. Besides, heterogeneous nucleation and graphene used as templates to direct material deposition have been proven an effective way to guide the growth of novel nanomaterials [ 2526 ].
However, these methods show limitation in large scale preparation for high quality materials. The results show it can achieve a high cell voltage of 1. Potassium permanganate KMnO 4 GO was synthesized by a modified Hummers method [ 29 ]. The preparation details of GO can be seen in the electronic supplementary information Supplementary Materials S1.
In detail, mg of GO was dispersed in mL of DI water by sonication for 1 h and transferred into three-necked mL round-bottomed flask. Then, the samples were collected and washed several times with deionized water. In two-electrode system, the activated graphene AG was also pressed between two nickel foams to form the negative electrode.
The electrochemical experiments were done in a classical three-electrode system which consists of working electrode, counter electrode, and reference electrode SCE. All the electrochemical measurements were carried out with a CHIE electrochemical workstation and repeated more than three times. Electrochemical impedance spectroscopy EIS was obtained by applying an AC voltage of 5 mV amplitude in the frequency range of 0. A high magnification SEM image Figure 1 b exhibits that the Mn 3 O 4 nanosheet with an average size of about nm Figure 1 c forms dense nanosheet area on graphene layers.
This image demonstrates that the lightweight conductive rGO with abundant wrinkles serves as an excellent conductive bracket for Mn 3 O 4 nanosheet attachment. It is notable that, after a long time of high-power sonication before tested with TEM, the Mn 3 O 4 nanosheet was still stably anchored on the graphene layer surface with high density, suggesting a strong interaction between graphene layers and Mn 3 O 4 nanosheet. In addition, the nanosheet could act as a barrier to prevent the adjacent restack of graphene sheets, thus avoiding losing their high active surface area.
The SAED pattern shows crystalline nature of Mn 3 O 4 nanoparticles and the diffraction rings which could be attributable to the,, and planes of Mn 3 O 4 nanosheet Figure 1 e. The planes are in accordance with the XRD results in previous reports [ 30 ].
The result of the interplanar spacing of the crystalline grains was 0. A minor broad diffraction peak appearing between The diffraction peaks at The C1s peak was best fitted in with two sharp peaks centred on at Additionally, the multiplet split of Mn 3s peak in Figure 3 c characterized the manganese oxidation state.
This split is attributed to the exchange interaction between remaining electrons in the 3s orbital and other unpaired electrons which have parallel spins. The splitting width 5. In the high resolution Mn 2p region, two peaks around at The CV obtained from different scan rates are near-perfect rectangular without distinct redox peaks. This feature reveals that the effective capacitance is attributed to pseudocapacitance of the Mn 3 O 4 nanosheet and double layer capacitance of rGO [ 34 ].
However, the CV curves gradually turn into a sharp tip towards 0. The CV shapes change little with scan rate increasing, suggesting lri high-rate capability of 01865 composite. The reason might be that graphene layer structure and the mesoporous structure of Mn 3 O 4 nanosheet provide excellent electron conductivity and high channels for ion diffusion.
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Electrochemical measurements in 0. Calculation details see Supplementary Materials S5 and S6. The specific capacitance decreases with current density increasing.
Here, the value of R s changed slightly from 1. In addition, just a slight increase of R ct changed from 0. These results demonstrate that there is no apparent difference before and after 10, cycles, indicating ideal capacitive behavior. The results of CV studies 1. The CV curves at li window between 0 and 1.
According to leu loadings of the positive and negative electrodes, the device delivers a relatively high capacitance of As shown in Figure 7 d, on basis of GCD curve at 0.
Electrochemical performance of oei ASC in 0. Long cycling ability is also a key factor in evaluating supercapacitor electrode material in practical applications. The promising capacitance retention of The points on the surface of samples selected for testing conductivity were exhibited in Figure 8 a.
On basis of solution-based redox 108865, the MnO 2 nanosheets were prepared and GO was employed as a template. The naked flame could enhance the process of decomposition, in which insulating functional groups over GO basal planes turned into CO 2 and H 2 O. Meanwhile, the MnO 2 nanosheets collapsed and turned into Mn 3 O 4 which are evenly anchored on the surface of graphene sheet. This low-cost method simplifies the electrode preparation process. The following are available online at http: The changes of the samples before and after the reaction triggered by the flame, Figure S2: Comparison of the fabrication process and electrochemical performance 1865 the as manganese oxide material in this work with those reported in previous literatures.
All authors were involved the drafting, revision and approval of the manuscript. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
National Center lej Biotechnology InformationU. Journal List Materials Basel v. Published online May Find articles by Yang Zhou. Find articles by Xuefeng Zou. Author information Article notes Copyright and License information Disclaimer. Received May 7; Accepted May This article is an open access lel distributed under the terms and conditions of the Creative Commons Attribution Lfi BY license http: This article has been cited by other articles in PMC. Associated Data Supplementary Materials materialss Abstract Benefiting from good ion accessibility and high electrical conductivity, graphene-based material as electrodes show promising electrochemical performance in energy storage systems.
Mn 3 O 4reduced graphene oxide, supercapacitors, flame plasma. Introduction Supercapacitors have attracted much attention owing to their robust lifetimes, rapid charging capabilities and high power energy storage for mobile phone, hybrid electrical vehicles, back-up power systems, ldi, and lift [ 1231008655 ]. Materials and Chemical Graphite powder Electrochemical Measurements The electrochemical experiments were done in a classical three-electrode system which consists of working electrode, counter electrode, and reference electrode SCE.
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Open in a separate window. Supplementary Materials The following are available online at http: Click here for additional data file. Conflicts of Interest The authors declare that the research was conducted in the absence of any commercial 1065 financial relationships that could be construed as a potential conflict of interest.
Carbon-based materials as supercapacitor electrodes. Supercapacitor devices based on graphene materials. Dual support ensuring high-energy supercapacitors via high-performance NiCo 2 S 4 Fe 2 O 3 anode and working potential enlarged MnO 2 cathode. Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super-capacitor electrodes.
High-quality porous cobalt monoxide nanowires ultrathin manganese dioxide sheets core-shell nanowire arrays on Ni foam for high-performance supercapacitor. Where do batteries end and supercapacitors begin?
Importance of polypyrrole in constructing 3D hierarchical eli nanotube MnO 2 perfect core-shell nanostructures for high-performance flexible supercapacitors. MnO x -decorated carbonized porous silicon nanowire electrodes for high performance supercapacitors. Interconnected MnO 2 nanoflakes assembled on graphene foam as a binder-free and long-cycle life lithium battery anode. Graphene-wrapped MnO 2 -graphene nanoribbons as anode materials for high-performance lithium ion batteries.