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The electrophysical properties of powders of carbon hybrid nanosized composites are studied depending on the content of single-wall carbon nanotubes (CNTs) and thermally reduced graphite oxide (TRGO). The effect of the bicomponent composition of the hybrid material is studied and the results of measurements of the specific low-frequency electrical conductivity at a frequency of 1 kHz, complex dielectric permittivity, and conductivity at a frequency of 9.8 GHz for the powders given above are presented. The effect of γ-irradiation on the measured characteristics of the powders is revealed. Research is aimed at finding fillers for modern effective composite radio-absorbing materials. [ABSTRACT FROM AUTHOR]

A comprehensive study aimed at finding fillers for modern composite radio-absorbing materials is carried out. The results of measurements of the electrophysical characteristics of powders of thermally reduced graphite oxide (TRGO), including presaturated acetic acid, are given. The effect of annealing the studied powders in the temperature range from 473 to 1173 K on low-frequency and microwave conductivity, density at pressures up to 5 MPa, and the magnitude of the EPR signal is considered. The results of measurements presented of the complex permittivity of all powders at a frequency of 9.8 GHz are presented. It is found that with an increase in the annealing temperature of the powders, their low-frequency and microwave conductivity increases, while the electron paramagnetic resonance (EPR) signal decreases. [ABSTRACT FROM AUTHOR]

The effect of annealing thermally reduced graphite oxide powders on their electrical conductivity and density at pressures up to 7 MPa is considered. The specific surface area of ​​the powders is determined at various temperatures of annealing. The complex permittivity of epoxy composites based on these powders used as fillers is measured at frequencies of 1.7, 2.9, and 9.8 GHz. The obtained average value of the dielectric loss tangent of the investigated composites in the specified frequency range exceeded the corresponding average value for epoxy composites based on natural graphite by 5–6 times. [ABSTRACT FROM AUTHOR]

Metal-fluoride nanoparticles, (MFx-NPs) with M = Fe, Co, Pr, Eu, supported on different types of thermally reduced graphite oxide (TRGO) were obtained by microwave-assisted thermal decomposition of transition-metal amidinates, (M{MeC[N(iPr)]2}n) or [M(AMD)n] with M = Fe(II), Co(II), Pr(III), and tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium, Eu(dpm)3, in the presence of TRGO in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]). The crystalline phases of the metal fluorides synthesized in [BMIm][BF4] were identified by powder X-ray diffraction (PXRD) to be MF2 for M = Fe, Co and MF3 for M = Eu, Pr. The diameters and size distributions of MFx@TRGO were from (6 ± 2) to (102 ± 41) nm. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were used for further characterization of the MFx-NPs. Electrochemical investigations of the FeF2-NPs@TRGO as cathode material for lithium-ion batteries were evaluated by galvanostatic charge/discharge profiles. The results indicate that the FeF2-NPs@TRGO as cathode material can present a specific capacity of 500 mAh/g at a current density of 50 mA/g, including a significant interfacial charge storage contribution. The obtained nanomaterials show a good rate capacity as well (220 mAh/g and 130 mAh/g) at a current density of 200 and 500 mA/g, respectively.

Graphical abstract Highlights • α-Fe 2 O 3 -TRGO is synthesized by using simple chemical wet method. • Surface area and conductivity of the composite, compared to α-Fe 2 O 3 , was successfully improved. • α-Fe 2 O 3 -TRGO was developed as an electrochemical sensor for detection of dopamine. • High sensitivity and lower detection limit of α-Fe 2 O 3 -TRGO was observed. Abstract Synthesis of hematite-thermally reduced graphite oxide (α-Fe 2 O 3 -TRGO) composite for the dopamine detection was carried out by a simple chemical method. The introduction of TRGO into α-Fe 2 O 3 improved electrochemical properties, resulting from larger electroactive surface area of composite (0.016 cm2), more than twice increase than that of α-Fe 2 O 3 (0.008 cm2), and higher conductivity as well. The electrocatalytic activity of α-Fe 2 O 3 -TRGO was investigated by the oxidation of dopamine in which a linear response of dopamine was obtained in the range of 0.1–5 mM with sensitivity of 0.02 mA/mM, limit of detection of 0.06 mM, and correlation coefficient of 0.99. [ABSTRACT FROM AUTHOR]

Abstract We report an efficient molybdenum disulfide (MoS 2) supported by thermally reduced graphite oxide and carbon nanotubes (TRGO-CNT) for hydrogen evolution reaction. The TRGO-CNT-MoS 2 composite is successfully prepared by a simple sonication process, exhibiting excellent catalytic activity of the hydrogen evolution reaction (HER) with a low overpotential of −0.14 V, which is much lower compared to that of MoS 2 , CNT-MoS 2 and TRGO-MoS 2 , respectively. TRGO-CNT-MoS 2 also exhibits high stability even after 1000 cycles and strong durability after 48 h. The high HER performance of TRGO-CNT-MoS 2 attributes to a synergic effect of thermal reduced GO and CNT that support MoS 2 due to significant decrease of electrochemical impedance and reliable supporting material for the efficient HER. Highlights • The TRGO-CNT-MoS 2 composite was prepared by a simple sonication method. • Lower overpotential of −0.14 V was obtained. • CNT, a bridge-like in the composite, enhanced the conductivity of TRGO-MoS 2. • The composite exhibited strong stability and long durability. [ABSTRACT FROM AUTHOR]

We report an efficient molybdenum disulfide (MoS 2 ) supported by thermally reduced graphite oxide (TRGO) for hydrogen evolution reaction (HER). The TRGO-MoS 2 composite exhibits excellent catalytic activity with a low overpotential of −0.23 V, which is almost three and seven times lower than those of precursor MoS 2 and GO-MoS 2 . The high performance of HER attributes to TRGO, providing a conducting network for fast electron transport from MoS 2 to electrodes. The composite also shows high stability in which the overpotential remains constant after 1000 cycles and strong durability after 48 h, demonstrating a synergistic effect of MoS 2 and TRGO for efficient HER. [ABSTRACT FROM AUTHOR]

Hemin-graphite oxide-carbon nanotube (hemin-GO-CNT) and hemin-thermally reduced graphite oxide-carbon nanotube (hemin-TRGO-CNT) composites are synthesized and investigated for the electrochemical supramolecular recognition by electron transfer between biomolecules (dopamine and hydrogen peroxide) and the composite electrodes. Redox reaction mechanisms of two composites with dopamine and hydrogen peroxide are explained in detail by using cyclic voltammetry and differential pulse voltammetry. Hemin-TRGO-CNT displays higher electrochemical detection for dopamine and hydrogen peroxide than that of hemin-GO-CNT, exhibiting enhancement of the electron transfer due to the effective immobilization of redox couple of hemin (Fe 2+ /Fe 3+ ) on the TRGO-CNT surface. [ABSTRACT FROM AUTHOR]

Systematic variation of copolymers (Poly (ethylene-covinylacetate)) composition provide an opportunity to change matrix polarities and thus explore their effects on the polymer/filler interactions and composite properties. The main objective of this work is to study the effect of vinyl acetate (VA) content on the extent of exfoliation and dispersion of thermally reduced graphite oxide (TrGO), as well as its impact on the thermal conductivity and mechanical properties of the resultant composites. The use of ethylene vinyl-acetate (EVA) copolymers of different (0–40 wt%) vinyl acetate content with similar melt viscosities allowed us to keep the processing conditions constant and quantitatively compare the thermal conductivity and mechanical properties of composites with different matrix polarities. Composites with conductive graphite (GT) and multiwalled carbon nanotubes (MWCNT) were also prepared and examined for comparison. Melt dispersion of TrGO in EVA copolymers was quantified using a range of characterization techniques: transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray scattering measurements. Electron microscopy and X-ray diffraction revealed highly exfoliated morphology of TrGO throughout the entire matrix, while GT remained multi-layer even after melt processing. Nanocomposites reinforced with TrGO showed significantly improved thermal conductivities and mechanical properties combined with low rheological percolation thresholds comparable to those achieved using MWCNT and GT. We propose a formalism to assess the thermal conductivity and mechanical properties of graphene nanocomposites based upon the interfacial excess energies of EVA copolymers. [ABSTRACT FROM AUTHOR]

The γ-cyclodextrin–graphite oxide–carbon nanotube (γCD–GO–CNT) composite has shown the best capability and sensitivity of supramolecular recognition compared to the other two CD-GO-CNT composites (αCD-GO-CNT and βCD-GO-CNT) in our previous study. The biggest CD (γCD) was very important in the formation of the supramolecular complex and made the detection of the biomolecules easier. In this report, significantly improved supramolecular recognition capability of γCD–GO–CNT is introduced by using thermally reduced GO (TRGO), instead of typical GO. New synthesized γCD–TRGO–CNT composite film shows lower electrochemical impedance, higher carbon to oxygen atomic ratio, and larger surface area compared to the γCD–GO–CNT composite film, resulting in higher sensitivity and capability in the supramolecular recognition. The sensitivity, defined as the slope of the maximum response current versus guest molecule concentration graph, increases significantly from 4.42 to 9.44 for dopamine and from 2.21 to 4.15 for ascorbic acid. The excellent enhancement of the supramolecular recognition of the γCD–TRGO–CNT composite is attributed to TRGO. It is, therefore, concluded that it is very important to load γCD in the composite as well as to decrease the electrochemical impedance for effective electrochemical biosensors. [ABSTRACT FROM AUTHOR]

The electrical and piezoresistive response of hybrid nanocomposites comprising a combination of few-layer thermally reduced graphite oxide (TRGO) and multiwall carbon nanotubes (MWCNTs) mixed with natural rubber is reported. The influence of the structure and morphology of the TRGO, and MWCNTs on the electrical and piezoresistive response of these nanocomposites is examined. All composites showed a different nonlinear piezoresistive behavior depending on the nanostructure (or combination) used. The hybrid combination of 2 wt.% TRGOs and 2 wt.% MWCNTs increased the electrical conductivity of the polymer 13 orders of magnitude, change that was not possible to achieve by using only TRGOs. This outcome can be attributed to the formation of a highly interconnected percolation network, and indicates that the morphology of the nanostructure plays a paramount role in the electrical and piezoresistive behavior of the nanocomposite. Platelet-type carbon nanostructures of the graphene family used as fillers for polymer composites may not outperform the electrical behavior of rod-type ones such as MWCNTs, but a tailored combination of both may be beneficial for the development of piezoresistive-based sensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low temperature reduction to ensure presence of hydroxyl (OH) and carboxyl (COOH) • Binding of active material on nickel foam due to OH and COOH groups. • Facile hydrothermal coating of active material on nickel foam. • High specific capacitance of 524 F/g at 1A/g. • Capacitive retention of 81.5 % after 1000 charge discharge cycles. Thermally reduced graphite oxide (TRGO) samples were hydrothermally deposited (120 °C, 12 h) on nickel foam current collector without any binder. TRGO of different reduction levels were synthesized through the thermal reduction of graphite oxide at 100 and 200 °C. The binding affinity of the oxygen functional groups enabled the binder free deposition. We could achieve specific capacitance C sp of 524 F/g (at 1 A/g) for Ni/TRGO200 and 136 F/g (at 1 A/g) for Ni/TRGO100 electrodes. These values are significantly larger than those till reported for binder free reduced graphite oxide electrodes. The capacitive retention of Ni/TRGO100 is 82.5 % and for Ni/TRGO200 it is 81.5 % over 1000 charge discharge cycles. Coulombic efficiency reaches 99 % and 100 % respectively for Ni/TRGO100 and Ni/TRGO200. Detailed analysis of the electrochemical storage mechanism is also reported. [ABSTRACT FROM AUTHOR]

Two types of carbonaceous materials, graphite oxide (GO x ) and thermally reduced graphite oxide (TRGO) were tested in the dyes removal from water. Two common synthetic aquatic pollutants, Orange II, an azo dye, and Rhodamine B, a xanthene dye, were selected as probe molecules and their bleaching was evaluated. We observed that the two materials act in a different way when dispersed in aqueous solution: TRGO acts as a good adsorbent material whereas GO x can be used as an efficient photosensitizer. Dye removal is almost complete in the dark in the presence of TRGO and within few minutes a steady-state concentration was achieved. On the contrary, in the case of GO x , adsorption is limited to almost 10–20% for both dyes, but this material is able to induce dyes photodegradation and almost 80% of the residual dyes are abated within 5 h of irradiation under simulated solar light. When the graphene derivatives were dispersed in UV-cured acrylic polymeric films, the reduction of the surface area dropped the adsorption properties of TRGO, whereas the photosensitizer properties of GO x were maintained and the bleaching of the two dyes was achieved. [ABSTRACT FROM AUTHOR]

Novel dispersions of thermally reduced graphite oxide (TRGO) in ester oil were prepared by means of high-pressure homogenization. Due to the versatility of the homogenization process, TRGO dispersions with a wide concentration range of 0.01-0.5 wt% could be prepared both in ester oil that contains additives (FGL46 E) and in an additive-free ester oil formulation. The obtained dispersions were characterized with respect to their sedimentation stability and their tribological properties. Therefore, highly resolved Stribeck curves were measured in the boundary region. Compared to benchmark dispersions of carbon black and graphite, our TRGO-containing formulations showed considerably lower friction and wear. The results of this study show the positive influence of TRGO on the friction behavior of ester oil formulations, thereby presenting TRGO-containing ester oils as a promising new family of liquid-based lubricants. [ABSTRACT FROM AUTHOR]

Abstract: Polyethylene/thermally reduced graphite oxide (TRG) composites were synthesized under mild conditions (1 atm ethylene and 40 °C) using (n-BuCp)2ZrCl2 activated with methylaluminoxane (MAO) as the polymerization catalyst. The composites were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), high temperature gel permeation chromatography (GPC), and light microscopy. Although the thermal properties of the aforementioned composites were relatively unchanged when compared to polyethylene, significant enhancements in the mechanical properties were observed (e.g., up to 57% increase in the tensile strength and 170% increase the Young's modulus for composites containing 5.2 wt% TRG). [Copyright &y& Elsevier]

Abstract: Herein we investigate the influence of carbon additives with different particle sizes and shapes on the flame retardancy and mechanical properties of isotactic polypropylene. Thermally reduced graphite oxide (TRGO) and multi-layer graphene (MLG250), consisting of few graphene layers, are compared with spherical, tubular and platelet-like carbon fillers such as carbon black (CB), multiwall nanotubes (MWNT) and expanded graphite (EG). The different morphologies control the dispersion of the carbon particles in PP and play a key role in structure–property relationships. Uniformly dispersed CB, MLG250 and TRGO shift the onset temperature of PP decomposition to temperatures around 30 °C higher, induce a flow limit in the composites' melt viscosity and change drastically their fire behaviour. The prevented dripping and significantly increased heat absorption result in decreased time to ignition and hardly any change in the reaction to a small flame. Under forced-flaming conditions reductions in the peak heat release rate of up to 74% are achieved due to the formation of a protective layer of residue during combustion. The described effects of carbon nanomaterials on the properties of PP composites are most pronounced for well-exfoliated graphenes, making them preferable to less exfoliated, micron-sized expanded graphite or conventional spherical and tubular carbon nanoparticles. [Copyright &y& Elsevier]

Abstract: Thermally reduced graphite oxide (TrGO) was prepared by thermal exfoliation and reduction of highly oxidized graphite. The pCBT/TrGO nanocomposites were prepared by in situ ring-opening polymerization (ROP) of cyclic butylene terephthalate (CBT). The polymerization kinetics of pCBT/TrGO was monitored by dynamic time sweep in a parallel-plate rheometer. It was found that the increasing TrGO content depressed the rate and degree of CBT polymerization, which is ascribed to the reaction between the growing pCBT chains terminated with carboxyl groups and TrGO surface groups such as hydroxyl and epoxy groups at the initial polymerization stage. The grafted pCBT chains were confirmed by X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) and thermogravimetric analysis (TGA) measurements, and the grafting content was up to 53 wt%. Small amplitude oscillation shear (SAOS) was applied to investigate the rheological properties of pCBT/TrGO and the critical loading to form percolation network was determined as 0.47 vol%, which confirmed the good dispersion of TrGO in matrix. The grafting reaction was also justified from nonlinear rheology and the fractal dimension analysis. [Copyright &y& Elsevier]

Thermally reduced graphite oxide and molybdenum disulfide (TRGO@MoS 2) is synthesized and modified by using solution plasma for hydrogen evolution reactions (HER). The HER performance of TRGO@MoS 2 increased with the plasma treatment time until 10 h and then saturated. Low overpotential of −64 mV at 10 mAcm−2 with a small Tafel slope of 32 mVdec−1 for HER, which is comparable to 30 mVdec−1 of platinum, was obtained in TRGO@MoS 2 after 10 h of the plasma treatment. The high HER performance attributes to the higher electrochemical active surface area, lower impedance, and smaller crystalline size in comparison with the precursor, proving that the plasma treatment introduces active surface area with improved conductivity which is a major factor for the efficient HER performance. • Successful modification of graphite oxide and molybdenum disulfide composites by the solution plasma. • The performance of hydrogen evolution reaction increased with the plasma treatment time until 10 h and then saturated. • Tafel slope, comparable to platinum, of the composite was obtained. [ABSTRACT FROM AUTHOR]

Metal-fluoride nanoparticles, (MF x -NPs) with M = Fe, Co, Pr, Eu, supported on different types of thermally reduced graphite oxide (TRGO) were obtained by microwave-assisted thermal decomposition of transition-metal amidinates, (M{MeC[N(iPr)] 2 } n ) or [M(AMD) n ] with M = Fe(II), Co(II), Pr(III), and tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium, Eu(dpm) 3 , in the presence of TRGO in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF 4 ]). The crystalline phases of the metal fluorides synthesized in [BMIm][BF 4 ] were identified by powder X-ray diffraction (PXRD) to be MF 2 for M = Fe, Co and MF 3 for M = Eu, Pr. The diameters and size distributions of MF x @TRGO were from (6 ± 2) to (102 ± 41) nm. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were used for further characterization of the MF x -NPs. Electrochemical investigations of the FeF 2 -NPs@TRGO as cathode material for lithium-ion batteries were evaluated by galvanostatic charge/discharge profiles. The results indicate that the FeF 2 -NPs@TRGO as cathode material can present a specific capacity of 500 mAh/g at a current density of 50 mA/g, including a significant interfacial charge storage contribution. The obtained nanomaterials show a good rate capacity as well (220 mAh/g and 130 mAh/g) at a current density of 200 and 500 mA/g, respectively.