•Nanorod Mn3O4@GNS was prepared by a simple, effective and scalable solvothermal technique.•The electrochemical properties of nanorod Mn3O4@GNS affected by the amount of graphene was investigated.•Nanorod Mn3O4@GNS exhibit superior Li-ion storage property.Nanorod Mn3O4 anchored on graphene nanosheet (Mn3O4@GNS) using GNSs and MnSO4·H2O as precursor materials have been prepared by a simple, effective and scalable method. The nanorod Mn3O4@GNS as anode materials in lithium-ion batteries exhibits the better electrochemical properties in the composite than the bare nanorod Mn3O4 owing to its special structure, including a maximum reversible specific capacity of 1155.2 mA h g−1 at 100 mA g−1, and the extraordinary cycling stability, with no decay in capacity for up to 100 cycles. The nanorod Mn3O4@GNS could be a promising candidate material for high reversible specific capacity, stable columbic efficiency, long cycle life and outstanding rate capacity. This study would offer a new method to improve the properties of insulating materials, holding a promising potential for high-performance lithium-ion batteries in energy storage fields.Download high-res image (261KB)Download full-size image

•Hedgehog-like CuO/N-GNS nanocomposite was prepared by a hydrothermal method.•N-GNSs can promote conductivity of hedgehog-like CuO and buffer volume change.•Hedgehog-like CuO/N-GNS nanocomposite exhibits superior Li-ion storage property.With a hydrothermal method, we have successfully prepared hedgehog-like CuO/nitrogen-doped graphene nanosheet (CuO/N-GNS) nanocomposite. The hedgehog-like CuO/N-GNS nanocomposite exhibits superior Li-ion storage properties in terms of high capacity, long cycle life, and excellent rate performance. After 50 cycles, hedgehog-like CuO/N-GNS nanocomposite exhibits higher discharge special capacity (750.1 mA h g−1) than hedgehog-like CuO (456.8 mA h g−1) at a current of 100 mA g−1. The cyclic stability of hedgehog-like CuO/N-GNS nanocomposite is better than that of hedgehog-like CuO, indicating that N-GNSs can further improve the cycle performance of hedgehog-like CuO owing to its high electrical conductivity and good buffer role. The hedgehog-like CuO/N-GNS nanocomposite has potential applications in the anodes of lithium-ion batteries.Download high-res image (258KB)Download full-size image

Ammonia-modified graphene nanosheets (AMGNSs)/epoxy nanocomposites were prepared by using a facile blend method. Graphene nanosheets (GNSs) were modified with aqueous ammonia (NH3·H2O) and hydrogen peroxide (H2O2), to obtain amine (–NH2) functionalized GNSs and to enhance the bonding between the GNSs and epoxy resin matrix. The effects of the AMGNSs on the static and dynamic mechanical properties of the nanocomposites were investigated. The results indicated that the tensile and flexural strength and modulus of the AMGNS/epoxy nanocomposites first increased and then decreased with increasing addition of AMGNSs. The addition of 0.5 wt% AMGNSs improved the tensile strength and flexural modulus of the pristine epoxy by 27.84% and 7.75%, respectively. Meanwhile, the addition of 0.1 wt% AMGNSs improved the tensile modulus and flexural strength of the pristine epoxy by 14.16% and 94.38%, respectively. The reinforcing effect of the AMGNSs in enhancing the impact properties of the epoxy nanocomposites was also examined. It was demonstrated that the amine-functionalization of GNSs with ammonia had an obvious effect on the mechanical performances of epoxy matrix nanocomposites.

•Graphene sheets (GSs), expanded graphite (EG) and natural graphite (NG) were comparatively investigated as anode materials for lithium-ion batteries.•The reversible capacity of GS electrode was almost twice that of EG electrode and three times that of NG electrode.•The first-cycle coulombic efficiency and capacity retention of NG were much bigger than those of GSs and EG.•GS and EG electrodes exhibited higher electrochemical activity and more favorable kinetic properties.Three kinds of carbon materials, i.e., graphene sheets (GSs), expanded graphite (EG) and natural graphite (NG) were comparatively investigated as anode materials for lithium-ion batteries via scanning electron microscope, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy and a variety of electrochemical testing techniques. The test results showed that the reversible capacities of GS electrode were 1130 and 636 mA h g−1 at the current densities of 0.2 and 1 mA cm−2, respectively, which were almost twice those of EG electrode and three times those of NG electrode. The first-cycle coulombic efficiency and capacity retention of NG were much bigger than those of GSs and EG. The notable capacity fading observed in GSs and EG may be ascribed to the disorder-induced structure instability. The larger voltage hysteresis in GS and EG electrodes was not only related to the surface functional groups, but also to the active defects in GSs and EG, which results in greater hindrance and higher overvoltage during lithium extraction from electrode. The kinetics properties of GSs, EG and NG electrodes were compared by AC impedance measurements. GS and EG electrodes exhibited higher electrochemical activity and more favorable kinetic properties during charge and discharge process.

An easy method of producing graphene sheets with high quality from mesocarbon microbeads (MCMBs) is demonstrated using oxidation, rapid expansion and ultrasonic treatment. Single layer graphene sheets have been successfully prepared from MCMBs through thermal exfoliation. The structure of the graphene sheets was investigated by scanning and transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. MCMBs expanded mainly along the c-axis and formed worm-like ellipses from the original regular spherules. Exfoliation continued with the fragmentation of the pieces and produced delamination of the graphene sheets. MCMBs can be an excellent starting material for producing high quality graphene sheets with high yields, becoming an attractive raw material for industrial up-scale.We employed an easy method to mass produce graphene sheets with high quality using oxidation, rapid expansion and ultrasonic treatment from mesocarbon microbeads (MCMBs). Single layer graphene sheets have been successfully prepared from MCMBs through thermal exfoliation. The structure of the graphene sheets were systematically investigated. MCMBs are excellent starting materials for producing high quality graphene nanosheets with high yields.Research Highlights► Single layer graphene sheets were prepared from mesocarbon microbeads (MCMBs). ► An easy method of producing high quality graphene sheets from MCMBs is demonstrated. ► MCMBs are excellent starting materials for producing high quality graphene sheets. ► A possible formation mechanism of graphene sheets from MCMBs is proposed.

The magnetite (Fe3O4) nanoparticles were prepared by coprecipitation of Fe3+ and Fe2+ using ammonium hydroxide (NH4OH) as a precipitating agent. The Fe3O4/polyethylene glycol (PEG) magnetic composite nanoparticles with a core–shell structure with a diameter of 10–40 nm were prepared by two step additions of the primary and the secondary surfactants, respectively. The inductive heat property of Fe3O4/PEG composite nanoparticles in an alternating current (AC) magnetic field was investigated. The potential of Fe3O4/PEG nanoparticles was evaluated for localized hyperthermia treatment of cancers. The saturation magnetization, Ms, and coercivity, Hc, are 67.06 emu g−1 and 7 Oe for Fe3O4 nanoparticles and 64.11 emu g−1 and 14 Oe for Fe3O4/PEG composite nanoparticles, respectively. Exposed in the AC magnetic field for 100 s, the temperatures of physiological saline suspensions containing Fe3O4 nanoparticles or Fe3O4/PEG composite nanoparticles are 89.2 °C and 72.2 °C, respectively. The Fe3O4/PEG composite nanoparticles will be useful as good thermoseeds for localized hyperthermia treatment of cancers.

Activated carbon fibers were prepared from rayon-based carbon fibers by two step activations with steam and KOH treatments. Hydrogen storage properties of the activated rayon-based carbon fibers with high specific surface area and micropore volume have been investigated. SEM, XRD and Brunauer–Emmett–Teller (BET) were used to characterize the samples. The adsorption performance and porous structure were investigated by nitrogen adsorption isotherm at 77 K on the base of BET and density functional theory (DFT). The BET specific surface area and micropore volume of the activated rayon-based carbon fibers were 3144 m2/g and 0.744 m3/g, respectively. Hydrogen storage properties of the samples were measured at 77 and 298 K with pressure-composition isotherm (PCT) measuring system based on the volumetric method. The capacities of hydrogen storage of the activated rayon-based carbon fibers were 7.01 and 1.46 wt% at 77 and 298 K at 4 MPa, respectively. Possible mechanisms for hydrogen storage in the activated rayon-based carbon fibers are discussed.

The magnetite (Fe3O4) nanoparticles with different magnetic properties were prepared by coprecipitation of Fe3+ and Fe2+ with an aqueous NaOH solution. The inductive heating property of Fe3O4 nanoparticles in an alternating current (ac) magnetic field was investigated. The potential of Fe3O4 nanoparticles was evaluated for localized hyperthermia treatment of cancers. The maximum saturation magnetization Ms of Fe3O4 nanoparticles was 65.53 emu g−1, which was synthesized under the condition of Fe3+/Fe2+ molar ratio at 1.8:1. The Ms of Fe3O4 nanoparticles decreased, while the coercivity Hc increased with the increase of Fe3+/Fe2+ molar ratio. Exposed in the ac magnetic field for 29 min, the temperatures of physiological saline suspensions containing different Fe3O4 nanoparticles are 42–97.5 °C. The inductive heating property of Fe3O4 nanoparticles in the ac magnetic field decreased as Hc increased, while increased with the increase of Ms. The Fe3O4 nanoparticles will be useful as good thermoseeds for localized hyperthermia treatment of cancers.

Carbon nanocoils were prepared by chemical vapour deposition, using commercial acetylene as carbon source, a nickel plate as a catalyst and a phosphorous compound as additive. The carbon nanocoils with diameters in the range of 80–100 nm and lengths of 5–50 µm are visible from FESEM images. Microwave absorption, complex permittivity and permeability of carbon nanocoils have been investigated at 2–18 GHz. Carbon nanocoils are chiral microwave absorbing materials and exhibit superior microwave absorption compared with the larger carbon microcoils. The reflection loss of the Nomex honeycomb sandwich composites filled with the carbon nanocoils is below − 10 dB (90% absorption) at 8.9–18 GHz in the range of 2–18 GHz, and the minimum value is − 32.23 dB at 12 GHz. The bandwidth corresponding to the reflection loss below − 10 dB is 8.1 GHz.

The multi-walled carbon nanotubes (MWNTs) were filled with long continuous Ag nanowires via a wet chemical method. The diameters of Ag nanowires were in the range of 10–20 nm, and lengths of 100–1500 nm. Microwave absorption and complex permittivity and permeability of MWNTs filled with Ag nanowires have been investigated in the range of 2–18 GHz, respectively. The reflection loss of the Ag nanowire filled MWNT/epoxy composites with the thickness of 1.0 ± 0.1 mm is below −10 dB in the range of 7.2–9.0 GHz, and the minimum value is −19.19 dB at 7.8 GHz. The microwave absorption of Ag nanowire filled MWNT/epoxy composites can be mainly attributed to the dielectric loss rather than magnetic loss. The absorption peak frequency of the MWNT/epoxy composites with thickness of 1 mm can be tuned by filling Ag nanowire into MWNTs.