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Graphical abstract Synthesis and microwave absorption properties schematic diagram. Abstract A novel hierarchical composites for coupling thistle-like CoNi with dielectric Ag decorated graphene in paraffin wax as high performance microwave absorber has been synthesized by a facile two-step strategy. The components, particle size, microstructure and morphology of the resulting composites are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra, scanning electron microscope, transmission electron microscopy and energy dispersive X-ray spectroscopy, etc. Due to the unique flower structure and good synergistic effect of dielectric loss and magnetic loss, thistle-like CoNi@dielectric Ag decorated graphene composites have showed glorious microwave absorption intensity and frequency width. The maximum reflection loss of −61.9 dB can be gained at 6.96 GHz, which has rarely been reported yet. In addition, the corresponding effective bandwidth with reflection loss less than −10 dB is 5.6 GHz ranging from 12.4 to 18 GHz at only 1.67 mm thickness. This highly efficient and broad band features endow thistle-like CoNi@dielectric Ag decorated graphene composites with promising applications in microwave absorption, electromagnetic shielding, information safety, direct broadcast satellite and military radar fields. [ABSTRACT FROM AUTHOR]

Abstract In this work, an eco-friendly and convenient microwave-assisted synthesis technique was applied in the entire experiment course. The first obtained graphene-Ni composite possess an unsatisfactory microwave absorption capacity due to unbalanced matching nature. Then a sulfurization process was tried at different temperatures to convert Ni into NiS/Ni 3 S 2 , and an innovative graphene-NiS/Ni 3 S 2 composite with a hierarchical architecture was fabricated under the condition of microwave irradiation. The investigation into microwave absorbing performances manifests that the absorption property of graphene-Ni can be obviously improved by sulfurization method. The results show, compared with graphene-Ni, the hierarchical-architecture graphene-NiS/Ni 3 S 2 composites generated at 150 ℃ (S-150) possess excellent absorbing ability with a maximum RL as strong as − 55.1 dB at 6.0 GHz with a thickness of 2.7 mm, and the effective bandwidth covers 8.6 GHz from 2.8 to 11.4 GHz with thickness varies in 1.5–4.5 mm range. The enhanced performances for S-150 mainly derive from the synergy of superior impedance matching character, high attenuation, dielectric loss and plenteous interface polarizations. [ABSTRACT FROM AUTHOR]

Porous SnO 2 /NiO/graphene ternary composites had been synthesized. Used as anode materials for lithium ion batteries, graphene supported porous SnO 2 /NiO ternary composites demonstrate excellent electrochemical performance and cycling stability. The first discharge capacity is 1280.4 mAh/g at a high current density of 300 mA/g. After 50 cycles, the reversible capacity is 410.74 mAh/g and the coulomb efficiency reaches at 99.4%. [ABSTRACT FROM AUTHOR]

The reduced graphene oxide (RGO)/cobalt ferrite (CoFe 2 O 4 ) composites with three different (RGO)/(CoFe 2 O 4 ) ratios were synthesized by a one-pot hydrothermal route. To research the influence of graphene reduction degree on electromagnetic parameters of graphene composites, RGO/CoFe 2 O 4 -2 was treated further by reduction process with different reducing agents (N 2 H 4 /NaBH 4 ). The crystalline structure, morphology, thermal stability, magnetic property of the synthesized samples were characterized by XRD, TEM, SEM, FT-IR, Raman, TG, VSM and XPS. The absorption properties of the RGO/CoFe 2 O 4 composites were studied. The maximum R L of RGO/CoFe 2 O 4 -2 composite is −47.9 dB at 12.4 GHz with a thickness of 2.3 mm, and the absorption bandwidth with the R L below −10 dB is up to 5.0 GHz (from 12.4 to 17.4 GHz) with a thickness of 2.0 mm. The results indicated that the RGO/CoFe 2 O 4 composites have remarkably electromagnetic performance, which are attributed to effective complementarities between the dielectric loss and the magnetic loss. Additionally, the microwave absorption properties of the RGO/CoFe 2 O 4 composites can be tuned easily by varying the (RGO)/(CoFe 2 O 4 ) ratio, the reduction degree of graphene and layer thickness of the samples. [ABSTRACT FROM AUTHOR]

Flower-like ZnO/CuO microstructures have been fabricated on Cu substrate via a simple hydrothermal method. The as-prepared ZnO/CuO flowers/graphene (GNS) composites had distributed the ZnO/CuO flowers on the graphene sheets. As anode materials for lithium ion batteries (LIBs), the ZnO/CuO flowers/GNS composites showed substantially higher reversible capacity and better cycling stability compared to ZnO/CuO flowers, which has been attributed to the improvement of structure stability and electrical contact by GNS. The method may be readily extended to synthesize other classes of hybrids based on graphene sheets for technological applications. [ABSTRACT FROM AUTHOR]

Hydriodic acid and self-assembly approach are used to fabricate graphene wrapped sulfur composite. The self-assembly process of the relative “large” graphene sheet and “small” sulfur is quite controllable, and the sulfur particles are completely enfolded by RGO sheets with a unique stacked structure .The RGO/S composite with 80 wt.% sulfur shows an initial discharge capacity of 865.1 mAh g −1 at 0.5 mA/cm 2 . A high specific capacity of 720 mAh g −1 with a coulombic efficiency of 95% is achieved after 50 cycles of charge/discharge. The material also delivered a capacity of more than 580 mAh g −1 at 2 mA/cm 2 and can be recovered to 736 mAh g −1 when the rate is returned to 0.2 mA/cm 2 , representing a promising cathode material for high current discharge lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Two kinds of hierarchical structures of graphene@Fe 3 O 4 @C@PANI (polyaniline) nanorod arrays were prepared by covalently and noncovalently grafting PANI nanorod arrays to the surface of graphene@Fe 3 O 4 @C, respectively. The measured electromagnetic parameters show that the bonding form between PANI nanorod arrays and graphene@Fe 3 O 4 @C have significantly effect on microwave absorption properties of graphene@Fe 3 O 4 @C@PANI nanorod arrays hierarchical structures, and the formation of covalent bond between PANI nanorod arrays and graphene@Fe 3 O 4 @C in hierarchical structures exhibits significantly enhanced microwave absorption performance. The maximum reflection loss is up to −44.2 dB at 11.4 GHz and the absorption bandwidth with a reflection loss below −10 dB ranges from 9.7 to 15.5 GHz with a thickness of 3 mm. Therefore, the high microwave absorption performance with lightweight and wide absorption frequency band can be realized by fabricating graphene-based hierarchical structures using covalent bond interaction. [ABSTRACT FROM AUTHOR]

The electromagnetic wave absorption properties of the ternary nanocomposites consisting of graphene, poly (3,4-ethylenedioxythiophene) and Fe 3 O 4 nanoparticles had never been reported. Herein, in order to expand the scope of electromagnetic wave absorption materials, the nanostructured graphene/poly (3,4-ethylenedioxythiophene) hybrid materials with Fe 3 O 4 nanoparticles had been synthesized by a controllable co-precipitation method. The nanocomposites were characterized by FTIR, XRD, TEM, Raman spectroscopy, XPS and TG analysis. The investigation of the electromagnetic parameters revealed that the excellent electromagnetic wave absorption properties of the nanocomposites may be attributed to the improved impedance matching, the enhanced interfacial effects and the geometric effect. The maximum reflection loss of the nanocomposites was up to −56.5 dB at 8.9 GHz and the absorption bandwidths exceeding −10 dB were 3 GHz with a thickness of 2.9 mm. Furthermore, our development strategies expanded the scope of the electromagnetic wave absorption materials and confirmed that the modification of graphene with poly (3,4-ethylenedioxythiophene) and Fe 3 O 4 nanoparticles makes the nanocomposites have a promising future in electromagnetic wave absorption materials. [ABSTRACT FROM AUTHOR]

Hollow Zn 2 SnO 4 boxes@C/graphene ternary composites with a three-dimensional triple buffering structure are prepared by two hydrothermal processes followed by a calcined process. The structure, morphology and electrochemical properties of the ternary composites were investigated by means of XRD, FTIR, Raman, BET, BJH, SEM, TEM, and electrochemical measurements. The hollow Zn 2 SnO 4 boxes are coated with carbon layer and then supported by graphene sheets to form a 3D carbon conductive network. Compared with the hollow Zn 2 SnO 4 boxes@graphene binary composites, the hollow Zn 2 SnO 4 boxes@C binary composites, the hollow Zn 2 SnO 4 boxes and the solid Zn 2 SnO 4 cubes, the hollow Zn 2 SnO 4 boxes@C/graphene ternary composites show an enhanced electrochemical performance (726.9 mAh g −1 at a current density of 300 mA g −1 after 50 cycles) and high rate capability. With the unique structure design, this kind of composites with excellent electrochemical properties can be a promising anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Highlights: [•] The ternary nanocomposites of GN–PANI–Fe3O4 were synthesized via a two-step method. [•] The size of Fe3O4 nanoparticles on GN–PANI is in the range of 5–20nm. [•] The maximum RL of GN–PANI–Fe3O4 is −43.9dB at 11.4GHz with a thickness of 2.5mm. [•] All the maximum RL was less than −24.2dB when the thicknesses vary from 2 to 4mm. [•] The bandwidths exceeding −10dB are 11.0GHz when the thicknesses in 2–4mm. [ABSTRACT FROM AUTHOR]

The composites of reduced graphene oxide-polyaniline film (RGO-PANI) were synthesized by an in situ polymerization method and the microwave absorption properties of the composites were investigated. FESEM results indicate that RGO is covered with polyaniline film, and some PANI nanoparticles with the diameter in the range of 10-30 nm embed in the film. As PANI film covered on RGO, the microwave adsorption properties of RGO are significantly enhanced. The maximum reflection loss of RGO-PANI is up to −41.4 dB at 13.8 GHz and the bandwidths exceeding −10 and −20 dB are 4.2 GHz (from 11.7 to 15.9 GHz) and 1.5 GHz (from 12.8 to 14.3 GHz) with a coating layer thickness of 2 mm. The excellent microwave absorption properties of the composites may be attributed to the unique structural characteristics and the charge transfer between RGO and PANI film. Thus, the composites can be used as an attractive candidate for the new type of microwave absorption materials. [ABSTRACT FROM AUTHOR]