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1.
High performance binder-free reduced graphene oxide nanosheets/Cu foam anode for lithium ion battery
Song Liu Hongying Hou Xianxi Liu Jixiang Duan Yuan Yao Qishu Liao 《Journal of Porous Materials》2017,24(1):141-147
Binder-free combination of reduced graphene oxide with Cu foam (RGO/Cu foam) anode for lithium ion battery was designed and achieved via one-step facile electro-reduction. The as-prepared composite RGO/Cu foam anode were studied in terms of scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR), Raman, galvanostatic charge/discharge, cyclic voltammogram and AC impedance. As expected, graphene oxide nanosheets were indeed successfully electro-reduced to large degree and tightly combined with Cu foam without any additional polymer binder. Moreover, the integrated RGO/Cu foam electrode delivered high reversible capacity of 1196.2 mAh/g at 0.25 A/g, indicating satisfactory electrochemical performances. High Li-storage activity, large surface area, high conductivity of RGO nanosheets and the binder-free combination with porous Cu foam should be jointly responsible for high electrochemical performances. 相似文献
2.
Graphene nanosheets have been investigated as cathode catalysts for lithium-air batteries with alkyl carbonate electrolyte. Field emission scanning electron microscopy, transmission electron microscope and Raman spectroscopy have confirmed the high quality of the as-prepared graphene nanosheets and the surface analysis has identified the mesoporous characteristic of graphene nanosheets. The electrochemical properties of graphene nanosheets as cathode catalysts in lithium-air batteries were evaluated by a galvanostatic charge/discharge testing. The reaction products on the graphene nanosheets cathode were analyzed by X-ray diffraction and Fourier transform infrared spectroscopy. The graphene nanosheet electrodes exhibited a much better cycling stability and lower overpotential than that of the Vulcan XC-72 carbon. This work demonstrated that graphene nanosheets could be an efficient catalyst for lithium-air batteries. 相似文献
3.
Hydrophilic graphene nanosheets were rapidly synthesized by reacting graphene oxide nanosheets with poly(sodium 4-styrene sulfonate) and simultaneously reducing by hydrazine hydrate under hydrothermal conditions. Organophilic graphene nanosheets were prepared by reacting with octadecylamine and reduction by hydroquinone through a reflux process. Ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy measurements confirmed the attachment of organic molecules to the graphene nanosheets to achieve hydrophilic and organophilic affinity. X-ray diffraction, Raman spectroscopy, and transmission electron microscopy analysis indicated that the crystal structure of the graphene nanosheets was maintained intact after chemical functionalisation. 相似文献
4.
Shweta Bhandari Melepurath Deepa Amish G Joshi Aditya P Saxena Avanish K Srivastava 《Nanoscale research letters》2011,6(1):424
Graphene nanosheets were prepared using a modified Hummer''s method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt. The as-produced graphene was characterized by X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM). In particular, the HR-TEM demonstrated the layered crystallites of graphene with fringe spacing of about 0.32 nm in individual sheets and the ultrafine facetted structure of about 20 to 50 nm of Au particles in graphene composite. Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope. Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties. 相似文献
5.
Binder-free combination of large area reduced graphene oxide (RGO) nanosheets with Cu foil was designed and achieved via one-step facile electro-reduction reaction. The obtained composite RGO/Cu foil electrode were studied in terms of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), Raman, galvanostatic charge/discharge, AC impedance and cyclic voltammetry (CV). As expected, large area RGO nanosheets with micron order of magnitude successfully formed and tightly combined with Cu foil without any additional polymer binders. Furthermore, RGO/Cu foil electrode delivered a reversible discharge capacity of 870.3 mAh/g after 110 cycles, indicating satisfactory cyclic stability and rate performance. High Li-storage activity, eminent conductivity and tight binder-free integration of RGO nanosheets with Cu foil current collector should be responsible for high electrochemical performances. 相似文献
6.
Thermal exfoliation and reduction of graphene oxide (GO) were performed to prepare graphene nanosheets at 300 °C under the ambient atmosphere without any supplementary conditions. The microstructure and morphology of the resulting graphene nanosheets were characterized with scanning electron microscopy, transmission electric microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The composite films based on poly(1-butene) (PB) and graphene nanosheets were prepared successfully through solution blending and compression molding. The morphological investigation suggested that the graphene nanosheets with nanoscale thickness achieved a homogeneous dispersion in the PB matrix. The composite films exhibited a sharp transition from insulating state to the conducting one with a low percolation threshold, followed by a high electrical conductivity at graphene content higher than 1.6 vol %. The composite films also achieved high dielectric constant with low dielectric loss due to the effective electrical conductive path established by graphene nanosheets in a local range. Moreover, the mechanical evaluation demonstrated that a considerable reinforcement was achieved for the composite films due to the strong interfaces between the graphene nanosheets and PB matrix. The introduction of graphene nanosheets not only enhanced the nucleation capability and crystallinity of PB domain but also improved the thermal stability of the composite films. In addition, the composite films showed an increase in storage modulus and a decrease in loss factors due to the incorporation of graphene nanosheets. 相似文献
7.
Furfuryl alcohol functionalized graphene nanosheets for synthesis of high carbon yield novolak composites
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Hossein Roghani‐Mamaqani Vahid Haddadi‐Asl Mehrzad Mortezaei Khezrollah Khezri 《应用聚合物科学杂志》2014,131(11)
Graphene oxide and furfuryl alcohol modified graphene nanosheets (G‐FA) were used to prepare graphene/novolak composites. Effect of graphene compatibilization on the properties of the composites especially carbon yield value is evaluated. Both types of graphene nanosheets were dispersed uniquely in the novolak matrix as proved by X‐ray diffraction analysis. However, modification of graphene sheets by furfuryl alcohol results in more improved dispersions. Thermogravimetric analysis confirms the elevated thermal stability of the nanocomposites in comparison with the neat novolak. In addition, G‐FA containing composites have higher carbon yield values. A shift in the wave number of characteristic bonds of graphene after oxidation and modification with furfuryl alcohol, O? H, C?O, and C? O bonds, are seen in the Fourier transform infrared spectroscopy spectra. Raman results and scanning electron microscopy images show that graphene nanosheets reduced in size and wrinkled by oxidation and functionalization. Transmission electron microscopy image of the composite with 0.2 wt % of G‐FA reveals the presence of nanosheets with curvature. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40273. 相似文献
8.
Burcu Saner 《Fuel》2011,90(8):2609-12571
Structural properties of graphene nanosheets that will be used as electrode material in fuel cells were investigated at different oxidation times. As the oxidation time was increased, the strong bonding between graphene layers in graphite was reduced and graphene layers started to exfoliate forming clusters with a few number of graphene layers. The variations in interplanar spacings, layer number and percent crystallinity indicated how stepwise chemical procedure influenced the morphology of graphite. It was possible to produce relatively flat graphene clusters with definite number of layers by controlling the oxidation time. Graphene nanosheets were characterized in detail by scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and thermal gravimetric analyzer. 相似文献
9.
Graphene–carbon nanotube hybrid materials were successfully prepared through the π–π interaction without using any chemical reagent. We found that the ratio between carbon nanotube and graphene had critical influences on the state in aqueous solution and morphology of hybrid materials. Field emission scanning electron microscope and transmission electron microscope analysis confirmed that graphene nanosheets wrap around individual carbon nanotubes and form a homogeneous three-dimensional hybrid nanostructure. When applied as an anode material in lithium ion batteries, graphene–carbon nanotube hybrid materials demonstrated a high reversible lithium storage capacity, a high Coulombic efficiency and an excellent cyclability. 相似文献
10.
Lijuan Wan Zhaoyu Ren Hui Wang Gang Wang Xin Tong Shuanghong Gao Jintao Bai 《Diamond and Related Materials》2011,20(5-6):756-761
A facile and rapid approach was used for the fabrication of chemically derived graphene nanosheets based on the reduction of graphite oxide (GO) in tube furnace assembly at different temperatures. The morphologies, microstructures, specific surface areas and other features of GO and graphene nanosheets were characterized. Structure characterization indicates that the platelet thickness of graphene nanosheets obtained at 300 °C was 1.62 nm, which corresponds to an approximately 5 layers stacking of the monoatomic graphene nanosheets. Electrochemical performances of the as-prepared graphene nanosheets were performed, the result of which could prove the above observation that graphene nanosheets (5 layers) obtained at 300 °C actually displayed the most remarkable electrochemical performances: the first discharge and charge capacities of graphene nanosheets were as high as 2137 mAh/g and 994 mAh/g, respectively, and after 100 cycles graphene nanosheets still possessed a high capacity of 478 mAh/g. 相似文献
11.
Synthesis of enhanced hydrophilic and hydrophobic graphene oxide nanosheets by a solvothermal method 总被引:1,自引:0,他引:1
We report that the hydrophilic affinity of graphene oxide nanosheets can be significantly increased by reacting with allylamine. High resolution transmission electron microscopy and electron diffraction analysis confirmed that the graphene oxide nanosheets were amorphous in structure. Hydrophobic graphene oxide nanosheets were also prepared via functionalising with phenylisocynate (C6H5NCO) through a solvothermal synthesis process. Hydrophobic graphene oxide nanosheets can be used as additives in polymer-based composites and other functional applications. 相似文献
12.
The effect of graphene nanosheets as an additive for anode materials in lithium ion batteries 总被引:1,自引:0,他引:1
Jae Hun Jeong Dong-Won Jung Byung-Sun Kong Cheol Min Shin Eun-Suok Oh 《Korean Journal of Chemical Engineering》2011,28(11):2202-2205
A small amount of graphene nanosheets was added to commercial graphite as an anode active material in lithium ion batteries
and its effects were examined through a variety of physical and electrochemical characterization techniques: FE-SEM, XRD,
Raman, BET, and EIS. Compared to a commercial graphite electrode, a composite electrode containing 1 or 5 wt% graphene nanosheets
showed higher reversible capacity and enhanced cyclability. This was attributed to the large surface area and low charge transfer
resistance of the graphene nanosheets. 相似文献
13.
Fellahi O Das MR Coffinier Y Szunerits S Hadjersi T Maamache M Boukherroub R 《Nanoscale》2011,3(11):4662-4669
This paper reports on efficient UV irradiation-induced reduction of exfoliated graphene oxide. Direct illumination of an aqueous solution of graphene oxide at λ = 312 nm for 6 h resulted in the formation of graphene nanosheets dispersible in water. X-Ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, atomic force microscopy (AFM) and electrochemical measurements (cyclic voltammetry and electrochemical impedance spectroscopy) suggest a restoration of the sp(2) carbon network. The results were compared with graphene nanosheets prepared by photochemical irradiation of a GO aqueous solution in the presence of hydrogenated silicon nanowire (SiNW) arrays or silicon nanowire arrays decorated with silver (SiNW/Ag NPs) or copper nanoparticles (SiNW/Cu NPs). Graphene nanosheets obtained by illumination of the GO aqueous solution at 312 nm for 6 h in the presence of SiNW/Cu NPs exhibited superior electrochemical charge transfer characteristics. This is mainly due to the higher amount of sp(2)-hybridized carbon in these graphene sheets found by XPS analysis. The high level of extended conjugated carbon network was also evident by the water insoluble nature of the resulting graphene nanosheets, which precipitated upon photochemical reduction. 相似文献
14.
《Ceramics International》2016,42(12):14066-14070
Ultrahigh temperature ZrB2-SiCw-Graphene ceramic composites are fabricated by hot pressing ZrB2-SiCw-Graphene oxide powders at 1950 °C and 30 MPa for 1 h. The microstructures of the composites are characterized by Scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The results show that multilayer graphene nanosheets are achieved by thermal reduction of graphene oxide during sintering process. Compared with monolithic ZrB2 materials, flexural strength and fracture toughness are both improved due to the synergistic effect of SiC whisker and graphene nanosheets. The toughening mechanisms mainly are the combination of SiC whisker and graphene nanosheets crack bridging, pulling out. 相似文献
15.
16.
Ruijin Meng Hongying Hou Xianxi Liu Jixiang Duan Song Liu 《Journal of Porous Materials》2016,23(3):569-575
Binder-free combination of graphene nanosheets with oriented TiO2 nanotube arrays was designed and achieved via one-step facile electrodeposition. The structure and morphology of as-prepared composite graphene nanosheets/TiO2 nanotube arrays were studied in terms of SEM, FESEM, EDX, TEM, Raman and FTIR. Furthermore, the corresponding electrochemical performances were evaluated in terms of galvanostatic charge/discharge, cycle stability and AC impedance. As expected, the composite graphene nanosheets/TiO2 nanotube arrays displayed higher discharge capacity, cycle stability and Li+ diffusion coefficient than bare TiO2 nanotube arrays. High Li-storage activity, superior conductivity and large surface area of graphene nanosheets should be responsible for improved electrochemical performances. 相似文献
17.
Xinlu Li Hongfang Song Hao Wang Yonglai Zhang Kun Du Hongyi Li Jiamu Huang 《Journal of Applied Electrochemistry》2012,42(12):1065-1070
A nanocomposite of graphene/MnO2 nanoplatelets was prepared by one-step chemistry route at room temperature. The microstructure was characterized by X-ray diffraction, N2 absorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Both TEM and SEM images show that MnO2 nanoplatelets are homogeneously distributed on the graphene nanosheets. The electrochemical properties were tested by cyclic voltammetry, galvanostatic charge–discharge experiments. The nanocomposite exhibited high lithium capacity (905?mAh?g?1 at 100?mA?g?1). The superior lithium storage capability can be attributed to the “open” structure: the large effective surface area and short diffusion paths. 相似文献
18.
Ying Chen Yong Zhang Dognsheng Geng Ruying Li Hanlie Hong Jingzhong Chen Xueliang Sun 《Carbon》2011,(13):4434-4442
A branched hybrid of MnO2/graphene/carbon nanotube (CNT) is generated in a one-pot reaction process by chemical method. Some ultrathin MnO2/graphene nanosheets, around 5 nm in thickness, are randomly distributed on the CNT surface. Morphology, phase structure, microstructure and vibrational properties of the hybrid were characterized by field emission scanning electron microscope, X-ray diffractometer, high resolution transmission electron microscope and Raman spectrometer. Elemental distribution of the hybrid was determined by energy dispersive X-ray mapping performed in scanning transmission electron microscope mode. The key factor of the formation mechanism is associated with both redox and oxidation–intercalation reactions. Graphene flakes are partly exfoliated from the surface layers of the CNTs, and the redox reaction between KMnO4 and hydroxyl groups occurs on both sides of these flakes, resulting in the formation of a MnO2/graphene/CNT hybrid. Brunauer–Emmett–Teller surface area measurements indicate that the hybrid has over four times the specific surface area of the pristine CNTs. 相似文献
19.
SnO2 nanoparticles were dispersed on graphene nanosheets through a solvothermal approach using ethylene glycol as the solvent. The uniform distribution of SnO2 nanoparticles on graphene nanosheets has been confirmed by scanning electron microscopy and transmission electron microscopy. The particle size of SnO2 was determined to be around 5 nm. The as-synthesized SnO2/graphene nanocomposite exhibited an enhanced electrochemical performance in lithium-ion batteries, compared with bare graphene nanosheets and bare SnO2 nanoparticles. The SnO2/graphene nanocomposite electrode delivered a reversible lithium storage capacity of 830 mAh g−1 and a stable cyclability up to 100 cycles. The excellent electrochemical properties of this graphene-supported nanocomposite could be attributed to the insertion of nanoparticles between graphene nanolayers and the optimized nanoparticles distribution on graphene nanosheets. 相似文献
20.
《Carbon》2015
Janus graphene oxide (GO) nanosheets functionalized by amino-containing chemicals were prepared via Pickering emulsion template. A wax-in-water Pickering emulsion was used to mask one side of GO nanosheets in order to achieve asymmetric chemical functionalization. Janus particles were obtained by removing the oil phase. The successful reaction of epoxy groups on the surface of GO with amino-containing chemicals was confirmed by Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA). The asymmetric surface structure of Janus GO nanosheets was detected by atomic force microscope (AFM) and X-ray diffraction (XRD). The efficient stabilization of an oil-in-water Pickering emulsion by Janus GO was proved. Polymer microspheres fabricated by using Janus GO as Pickering stabilizer had a more hydrophilic surface compared with those stabilized by symmetrically modified GO. 相似文献