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Spinel ferrite based nanoparticle material has been at the forefront of contemporary nanotechnology for use in various industrial and biomedical applications. The preparation and characterization o...

Multi-walled carbon nanotube (MWCNT)/dextran/nano-gold composite was prepared by chemical solution reaction. The average diameter of gold nanoparticles was around 15 nm. MWCNT/dextran/nano-gold composites were uniformly dispersed in aqueous solution as electrode materials. MWCNT/dextran/nano-gold composites exhibited excellent electrochemical property in [Fe(CN)6]3– /4– solution. Experimental results showed that the MWCNT/dextran/nano-gold composites with 50% MWCNTs presented obvious redox peak and low impedance and had good electrochemical response to Cu2+. The redox peak currents were linear while the concentration of copper ions ranged from 1× 10–2 to 1 × 10–4 M. The relationship between oxidation peak currents I (A) and Cu2+ concentration C (M) was: ipk (A) = 2.6207 × 10–6 + 43.91572 × 10–4 × C (M), and the limit of determination (LOD) of Cu2+ was 0.63 × 10–6 M, and linear coefficient was 0.9923.

The development of high dielectric loss and magnetic loss for radar absorbing material is a long-term pursuing and under a close scrutiny. Most of the researches have been focused on exploring absorber materials with good absorption performance and at the same time with a good electrical conductivity. To develop a new absorber material will also have significant impacts on boosting the dielectric loss and magnetic loss. Herein, 3D spherical NiCo2S4 (NCS)-based composite has been fabricated via a mild, simple and useful hydrothermal strategy and the electromagnetic wave absorbing properties have been investigated through comparison among NCS, acidified carbon nanotubes (a-CNT)/NCS, reduced graphene oxide (r-GO)/NCS and r-GO/a-CNT/NCS. The experimental results show that the optimal concentration of NiSO4·6H2O to synthesize the composites is 6 M. Furthermore, the frequency bandwidth has been broadened and the maximum absorption peaks have been increased after adding the modified agent. The maximum frequency bandwidth of r-GO/a-CNT/NCS is 5.1 GHz below −5 dB and 2.7 GHz below −10 dB respectively, the maximum absorption peak is −35.8 dB at 8.1 GHz.

To improve the mechanical properties and oxidation resistance of short carbon fiber reinforced silicon carbide matrix composites, carbon nanotubes (CNTs) were grown in-situ on carbon fiber surfaces through continuous CVD, a small amount of phenolic formaldehyde (PF) was added to the matrix to densify the composite and interlock the fiber and the matrix. The CNTs-Cf/PF/SiC composite was fabricated by combining pre-casting and hot-pressing. Microstructural analyses revealed that CNTs were successfully grown on carbon fiber surfaces with entangled structures, while PF presented cobweb-like structure which tightly bonded the fiber and the matrix. Compared with CNTs-Cf/SiC and Cf/SiC, the flexural strength of CNTs-Cf/PF/SiC increased by 15.27% and 51.95%. After heat treatment, the weight loss of CNTs-Cf/PF/SiC reached 21.05%, and 31.9% of flexural strength retained after 15 thermal shock cycles at 1400 °C. These enhanced properties were indicative of its enormous potential to replace traditional Cf/SiC composite.

In this work, a high-performance electrode material has been fabricated by the incorporation of carbon nanotubes (CNTs) and polyaniline (PANI) on a carbon foams (CF) to improve its electrochemical performance. The microstructure and performance of as-prepared material was characterized in detail. Results showed that the resultant material exhibited a high gravimetric capacitance up to 467.1 F g−1, higher energy density of 104. 2 Wh kg−1 and power density of 3000 W kg−1 at a current density 3 A g−1 when the electrochemical doping time of PANI equals to 20 min. Furthermore, it appeared a good cycling stability with capacitance retention of 94.5% after 10000 cycles. The enhanced electrochemical performance can be attributed to the unique carbon nanostructure and synergistic effects of active materials CNTs and PANI. It indicates that this novel CF/CNTs/PANI-20 composite is a promising candidate for electrochemical capacitors.

Single-walled carbon nanotubes (SWCNTs) were prepared by a modified arc discharge furnace using 500 Torr helium as buffer gas at 600 °C. The effect of the catalyst type on the production of SWCNTs ...

In order to investigate the possibility of producing novel perovskite materials for fabricating solar cells with low toxicity, the influence of Sn substitution for Pb on the structural, electronic, and optical properties of the pentarnary compounds CsPb8-xSnxIBr2 and CsPb8-xSnxI2Br (for 1 ≤ x ≤ 7) was investigated by density functional theory (DFT) calculations using the GGA-PBE approximation. The predicted structure of these new pentarnary materials is cubic. Their optical absorption coefficient is predicted to be in the range of 105 cm−1, which is a good match with that of the Sn-free CsPbIBr2 and CsPbI2Br compounds. The increase in Pb concentration causes an increase in the bandgap as well as in the optical absorption coefficient, which reveal the key role of Pb in perovskite solar cells. The compounds with the highest Pb concentration, CsPb7SnIBr2 and CsPb7SnI2Br, exhibited a promising bandgap of 1.31 and 1.29 eV, respectively, which is close to the Shockley-Queisser bandgap limit that is the best for solar-cell applications. The above properties, in conjunction with their relatively easy synthesis process, qualify these new predicted materials for being included in the family of the mixed-halide perovskites.

Recently, copper sulfide (CuS) quite arouses researchers' interest due to its high theoretical capacity and excellent electroconductivity. However, poor cycling stability seriously limited the application in supercapacitors. In addition to the improvement of cycling performance, it is also a challenge to develop electrode materials with energy density. Herein, RGO/CuS composite is prepared successfully by solvothermal reaction methods. By the observation using FESEM and TEM, CuS microstructure displays regular and tiny nanoparticles, which are supported by RGO sheets. After the electrochemical measurements, RGO/CuS composite exhibits a maximum specific capacitance of 946 F g−1 at 10 mV s−1 and 906 F g−1 at 1 A g−1, respectively. The excellent cycling stability is also achieved and it maintains 89% retention after 5000 cycles at 5 A g−1. RGO/CuS composite also possesses high energy density of 105.6 W h kg−1 at the power density of 2.5 kW kg−1, which indicates that RGO/CuS composite has a bright future as electrode materials for supercapacitors.

In this work, a long-life and high-performance electrode material is successfully fabricated by the incorporation of carbon nanotube (CNT) with different length using chemical vapor deposition (CVD) on a hierarchically three dimensional (3D) carbon foam (CF), which is obtained from the mesophase pitch. The morphology, composition, and electrochemical performance of the as-prepared composites are characterized using the scanning electron microscope (SEM), Raman spectroscopy, X-ray diffraction (XRD) patterns, cyclic voltammetry, and galvanostatic charge/discharge cycling techniques. Characterizations suggest that this resultant CF/CNT-50 electrode material has a good cycling stability with capacitance retention of 96.5% even after 10000 cycles. Moreover, it shows a high mass capacitance of 227.5 F/g based on the resultant electrode materials, higher energy density of 28 Wh kg−1 and power density of 3700 W kg−1 at a current density 2 A g−1 and also excellent charge/discharge rate. These measured charge storage properties make the proposed hybrid materials excellent electrode material candidates for high performance supercapacitors.

Coiled amorphous carbon nanotube (CACNT) array was prepared by chemical vapor deposition method. The experimental results indicated that the length of as-prepared CACNT array was about 30 μm. The electromagnetic wave absorbing properties were studied through comparison among CACNTs, CACNT-La(NO 3 ) 3 , CACNT-(Fe, Co, Ni) and CACNT-reduced graphene oxide (RGO). The experimental results showed the maximum frequency bandwidth of CACNT-(Fe, Co, Ni) was 6.4 GHz below −5 dB and 2.3 GHz below −10 dB separately. Compared to the pure CACNTs, all the frequency bandwidth had been broaden after adding the modified agent. Meanwhile, the additive of rare earth ions La 3+ could effectively increase the maximum absorption peak (−17.94 dB at 8.96 GHz).

Multi wall carbon nanotubes (MWCNTs) and diamond nanoparticles (DNPs) reinforced carbon foam composites were prepared by the direct pyrolysis of MWCNTs, DNPs and mesophase coal tar pitch mixture. The effect of additive amounts on the microstructure and properties of carbon foams were studied. Significant impacts on the microstructure of carbon foams were observed after the incorporation of additive amounts. Whereas, the additive behavior of MWCNTs and DNPs were further investigated in terms of adsorption, mechanical and thermal properties. The results shows that the nickel (Ni) and cadmium (Cd) metal ions adsorption tendency increases with the increase of MWCNTs and DNPs contents. The maximum adsorption percentage of 84.6 and 86.9% was observed for carbon foam containing 2 wt% MWCNT-DNPs loading for Ni and Cd ions respectively. Furthermore, the compressive strength and thermal conductivity of the carbon foams were enhanced with the increase of additives amounts. Maximum improvement of 19.22 MPa in the compressive strength and 37.46 W/m K at 800 °C of thermal conductivity was revealed by carbon foam composite containing 4 wt% MWCNT-DNPs additive amounts.

The pursuing aim of high reflection loss and broad frequency bandwidth for electromagnetic wave (EMW) absorbing materials is a long-term task and under a close scrutiny. To construct rational microstructures for the absorber have significant impacts on increasing reflection loss and broadening frequency bandwidth. Herein, we presented a sandwich microstructured expand graphite (EG)/BaFe12O19 (BF) nanocomposite successfully prepared by in-situ sol-gel auto-combustion method. The experimental results showed that EG/BF nanocomposite has better EMW absorbing performance than pure EG and BF, the sandwich microstructured EG/BF connected with carbon nanotubes (CNTs) could further improve the electromagnetic performance effectively. The obtained CNT/EG/BF nanocomposite exhibited a saturation magnetization of 26.5 emu g−1 at room temperature and an excellent EMW absorbing performance. The maximum reflection loss of the sandwich microstructured CNT/EG/BF composites with a thickness of 1 mm was up to −45.8 dB and the frequency bandwidth below −10 dB could reach to 4.2 GHz within the frequency range of 2–18 GHz. The research results indicated that the prepared nanocomposite showed great potential as a new type of microwave absorbing material.

Homogeneous amorphous carbon nanotube (ACNT) networks have been synthesized using floating catalyst chemical vapor deposition method on a 3D graphene aerogel (GA)/ BaFe12O19 (BF) nanocomposite which was prepared by a self-propagating combustion process. The as-synthesized ACNT/GA/BF nanocomposite with 3D network structures could be directly used as a good absorber material for electromagnetic wave absorption. The experimental results indicated that the minimum reflection loss of ACNT/GA/BF composite with a thickness of 2 mm was −18.35 dB at 10.64 GHz in the frequency range of 2–18 GHz. The frequency bandwidth of the reflection loss below −10 dB was 3.32 GHz and below −5 dB was 6.24 GHz, respectively. The 3D graphene aerogel structures which composed of dense interlined tubes and amorphous structure bearing quantities of dihedral angles could consume the incident waves through multiple reflection and scattering inside the 3D web structures. The interlinked ACNTs have both the virtues of amorphous CNTs (multiple reflection inside the wall) and crystalline CNTs (high conductivity), consuming the electromagnetic wave as resistance heat. ACNT/GA/BF composite has a good electromagnetic wave absorption performance.

In this article, three-dimensional (3D) heterostructured of MnO2/graphene/carbon nanotube (CNT) composites were synthesized by electrochemical deposition (ELD)-electrophoretic deposition (EPD) and subsequently chemical vapour deposition (CVD) methods. MnO2/graphene/CNT composites were directly used as binder-free electrodes to investigate the electrochemical performance. To design a novel electrode material with high specific area and excellent electrochemical property, the Ni foam was chosen as the substrate, which could provide a 3D skeleton extremely enhancing the specific surface area and limiting the huge volume change of the active materials. The experimental results indicated that the specific capacitance of MnO2/graphene/CNT composite was up to 377.1 F g−1 at the scan speed of 200 mV s−1 with a measured energy density of 75.4 Wh kg−1. The 3D hybrid structures also exhibited superior long cycling life with close to 90% specific capacitance retained after 500 cycles.

In this work, reduced graphene oxide (RGO) - carbon nanotubes (CNT) grown on carbon fiber (CF) is fabricated by a combination of electrophoretic deposition (EPD) and chemical vapor deposition (CVD). Firstly, CF-GO composite is prepared via EPD. Secondly, the CF-RGO-CNT hybrid is obtained by floating catalyst chemical vapor deposition method for synthesizing CNT on the CF-RGO substrate. The as-prepared three-dimensional (3D) hierarchical hybrid shows strong mechanical stability and high flexibility at various bending angles. Furthermore, the hybrid is characterized by scanning electron microscope, X-ray Diffraction and Raman spectroscopy, and its supercapacitor properties are also tested. The electrochemical measurements display a higher specific capacitance of 203 F g−1, 4 times higher than that of pure CF. Importantly, the hybrid shows high electrochemical stability at various bending angles, and can be directly served as flexible electrode with binder-free for high-performance supercapacitors. All these attractive results indicate that the as-prepared 3D hybrid is a promising candidate for flexible supercapacitor applications.

A coral-like amorphous carbon nanotube was prepared by a modified arc discharging furnace in hydrogen atmosphere with a mixture of Mo-Co2O3-Mg powders as catalyst at 600°C. This carbon nanotube presented a microscopic coral-like by SEM observation and amorphous structure of nanotubes by HRTEM observation. The XRD diffraction and Raman pattern presented noncrystal characteristics compared to the normal graphite structure. We believed that these results may be affected by the “synergistic” effect of catalyst, atmosphere, and temperature in the synthesis process. The possible explanations to the formation mechanism of this novel carbon nanotube have also been proposed.

The development of more advanced and environmentally friendly energy storage devices is an urgent request to meet future societal and environmental needs. Supercapacitor is one of the most promising electrochemical energy storage devices owning to its long cycle life, high dynamic propagation, quickly response and low maintenance cost compared to the traditional batteries and capacitors. However, their energy density is far less batteries, which limits their application in energy storage. In order to break through the limitation, exploring novel electrode materials with both high energy densities and power densities is extremely urgent. At present, it is a hot topic to produce composite electrode materials with synergistic effect. Graphene, a one-atom-thick two dimensional single layer of sp2-bonded carbon, owning to its unique structural properties, has exhibited many advantages, such as extraordinarily high electrical and thermal conductivity, great mechanical strength and high surface area, making it a potential candidate for applications in energy storage field. Therefore, graphene based composite materials have been utilized in various practical applications, including energy storage and conversion, transparent conducting films, chemical sensors, and actuators, etc. Given the extraordinary properties of graphene, such as the low mass density, good compatibility, highly conductive, large specific surface area and excellent flexibility, it is considered as one of the most suitable substrate materials for preparing supercapacitor electrodes. In recent years, graphene composites as supercapacitor electrode material have been widely investigated. Here, three- dimensional (3D) graphene/carbon nanotube (CNT) nanocomposites were prepared by in-situ compound method using as-synthesized graphene as matrix, which prepared by chemical vapor deposition (CVD). Firstly, graphene was prepared on Ni foam by CVD method using CH4 as carbon sources and H2/Ar as buffer gas at 850°C. Then a solution carbon source was obtained by ultrasonic vibration using a mixture solution of ferrocene and dimethylbenzenes. Finally, 3D graphene/CNT nanocomposite was synthesized by CVD method using Ni foam deposited graphene as supporter substrate at 750°C for 30 min. The morphology and microstructure of the resulting samples were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the electrochemical capacitive performance of the samples were investigated using CHI 660D chemical workstation to analyze the cyclic voltammetry and AC impedance. The results indicated that large amounts of graphenes had been formed on the Ni foam and 3D graphene/CNT nanocomposites also had been synthesized. The 3D lamellar structures between graphenes formed in the synthesis process could densely upload active substance, which was very different in structure and performance with individual graphene. The cyclic voltammetry (CV) curves of 3D graphene/CNT composite exhibited that the electrochemical capacitive performance has good reversibility. The Nyquist plots also displayed that the 3D graphene/CNT composite has excellent performance of electric charge transportation and double layer capacitance. The electrochemical measurements indicated that the maximum specific capacitance of 3D graphene/CNT composite, as the supercapacitor electrode material, exhibited a maximum specific capacitance of 289.8 F/g using 1.5 mol/L Li2SO4 as the electrolyte in the system and also showed excellent high-capacity and cycling stability. The specific capacitance of the 3D graphene/CNT composite remains 92% after 2000 cycles.

Single-walled carbon nanotubes (SWCNTs, the mean diameter of 1.35 nm) were produced by a modified arc discharging furnace using a mixture powder of KCl and Co-Ni alloy as catalyst at 600°C. The hydrogen storage capacity of SWCNTs was enhanced by the mechanism of atom hydrogen spillover from the supported catalyst. The temperature effect on the hydrogen storage capacity of as-grown SWCNTs was investigated. The relative experiments of SWCNT hydrogen uptake and release were carried out by a high-pressure volumetric gas-adsorption measurement system. The experimental results indicated that the hydrogen storage capacity of SWCNTs increased with the environmental temperatures decreasing. The hydrogen storage capacity of SWCNTs was up to 1.73 wt% at 77 K for 2 hours under the pressure of 10 MPa, and the corresponding releasing hydrogen capacity is about 1.23 wt% under ambient pressure.

Three-dimensional (3-D) graphene foam/PANI nanorods were fabricated by hydrothermal treatment of graphene oxide (GO) solution and sequentially in-situ synthesis of PANI nanorods on the surface of graphene hydrogel. 3-D graphene foam was used as substrate for the growth of PANI nanorods and it increases the specific surface area as well as the double layer capacitance performance of the graphene foam/PANI nanorod composite. The length of the PANI nanorod is about 340 nm. PANI nanorods exhibited a short stick shape. These PANI nanorods agglomerate together and the growth orientation is anisotropic. The highest specific capacitance of 3-D graphene/PANI nanorod composite electrodes is 352 F g−1 at the scan rate of 10 mV s−1.

This paper describes the characterization of a three-dimensional (3D) reduced graphene oxide (RGO)-carbon nanotube (CNT)-polyaniline (PANI) hybrid fabricated by combining electrophoretic deposition (EPD) and floating catalyst chemical vapor deposition (FCCVD), followed by in - situ anodic electrochemical polymerization (AEP). Firstly, the RGO-CNT is prepared by combining EPD of GO onto nickel foams (NF) and then growth of uniformly aligned CNT on the surface of RGO via FCCVD. Secondly, the 3D RGO-CNT-PANI hybrid is successfully fabricated by in situ AEP of aniline monomers onto the surface of the RGO-CNT. The structures and morphologies of the hybrid have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X - ray diffraction (XRD) and X-ray photoelectron spectrometer (XPS). Electrochemical properties are studied by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The results reveal that the as-prepared hybrid based on the two - electrode system displays very high specific capacitance of 741 F g −1 with a high energy density of 92.4 Wh kg −1 and high power density of 6.3 kW kg −1 at the scan rate of 10 mV s −1 . Additionally, the hybrid shows good cycling stability with a retention ratio of 95% after 5000 cycles. These attractive results suggest that this 3D RGO-CNT-PANI hybrid has a great potential as an electrode material for high performance supercapacitors.

The improvement of high reflection loss and broad frequency bandwidth for electromagnetic wave absorption materials is a long-term effort. The superb micro-structures of the absorber have significant impact on increasing reflection loss and broadening frequency bandwidth. Herein, we prepared 3D graphene by chemical vapor deposition and then 3D graphene/pine needle-like iron nano-acicular whisker composites were in situ synthesized by an electrochemical deposition process under an electric field using 3D graphene as substrate. The nano-acicular whiskers show different sizes and the mean diameter of the individual iron nano-acicular whiskers was about 150 nm. The saturation magnetization (MS) of the 3D graphene/iron nano-acicular whisker composite was about 42.65 emu g−1 and the coercivity (Hc) was 143 Oe, and it shows good magnetic properties. In the frequency range of 2–18 GHz, the reflection loss value of the graphene/iron nano-acicular whisker composites with a thickness of 2 mm could reach −12.81 dB at 10.95 GHz and the effective absorption bandwidth below −10 dB was 2.16 GHz. The nano-acicular whiskers could effectively improve the electromagnetic wave absorbing properties. The results suggested that the as-prepared graphene/iron nano-acicular whisker nanocomposite showed great potential applications as a new absorber material.

The development of high reflection loss and broad frequency bandwidth for electromagnetic wave absorbing materials has been pursued for a long time. Constructing a rational microstructure of an absorber will have significant impact on reflection loss increase and frequency bandwidth broadening. Herein, we successfully prepare a sandwich microstructured graphene/BaFe12O19 nanocomposite by an in situ auto-combustion method. Compared to pure BaFe12O19, the sandwich microstructured graphene/BaFe12O19 showed better electromagnetic wave absorbing properties. Furthermore, the sandwich microstructured graphene/Ba0.8La0.2Fe12O19 nanocomposite was prepared with La-doped BaFe12O19 using the same method. The obtained graphene/Ba0.8La0.2Fe12O19 nanocomposite exhibited a saturation magnetization of 26.55 emu g−1 at room temperature and exhibited excellent magnetic performance. The maximum reflection loss of the sandwich microstructured graphene/Ba0.8La0.2Fe12O19 nanocomposite with a thickness of 1 mm could reach up to −40.26 dB, and a frequency bandwidth value below −10 dB was observed up to 3.87 GHz within the frequency range of 2–18 GHz.

The 3D interlinked amorphous carbon nanotube (ACNT)/reduced graphene oxide (RGO)/BaFe12O19 (BF) composite was directly prepared by a self-propagation combustion process. The RGO was synthesized in situ through the massive heat release during the auto-combustion reaction. The interlinked ACNTs and graphene as well as BF formed the conductive networks for improving the dielectric and magnetic loss. The reflection loss peak of ACNT/RGO/BF composite was −19.03 dB at 11.04 GHz in the frequency range of 2–18 GHz. The frequency bandwidth of the reflection loss below −10 dB was 3.8 GHz. The 3D interlinked ACNT-RGO structure, which was composed of dense intertwined ACNT and graphene with quantities of dihedral angles, could consume incident waves via multiple reflections inside the 3D structures. The high conductivity of 3D interlinked ACNT/RGO networks would lead to energy dissipation in the form of heat through molecular friction and dielectric loss.

In this work, we proposed a new method to prepare graphene nanosheets. Expand graphite has large sheet spacing and oil absorption, and the self-combustion precursor of BaFe12O19 is oily gel. It means that the BaFe12O19 oily gel can enter between the layers of expand graphite. When BaFe12O19 oily gel is self-combusted to form BaFe12O19 particles, it has a significant increase in volume. Expand graphite will occur secondary expansion and be peeled into graphene nanosheets. We characterized it by several ways and this is a time-saving, convenient, and low-cost method.

A flexible filter paper based composite electrode was prepared via the convenient one-step synthesis of silver doped graphene for the first time, followed by in-situ polymerization of aniline monomers. Using L-ascorbic acid for simultaneous reduction of grapheme oxide and silver nitrate, we provided a new and green method to prepare graphene hybrid sheets without toxicity. It was found that the as-fabricated hybrid electrode formed a three-dimensional porous architecture, which not only increased the specific surface area of composite, but also facilitated the ion diffusion of the electrolyte. In addition, according to the tests of electrochemical performances, the flexible hybrid electrode subsequently exhibited exceptional specific capacitance of 437.3 F/g, energy density of 1133.5 W&middot, h/kg and power density of 88.8 kW/kg, respectively. Meanwhile, the as-prepared hybrid demonstrated a good cycling stability with only 10.99% specific capacitance deterioration after 5000 times of cycling. This preparation technology presented here shows great potential for the development and application of wearable and portable energy storage devices, particularly for flexible supercapacitors. Moreover, this study puts forward a general, simple and low-cost route of fabricating a novel flexible electrode on a large scale, eventually for environmental protection.

The thermally conductive properties of silicone thermal grease enhanced by hexagonal boron nitride (hBN) nanosheets as a filler are relevant to the field of lightweight polymer-based thermal interface materials. However, the enhancements are restricted by the amount of hBN nanosheets added, owing to a dramatic increase in the viscosity of silicone thermal grease. To this end, a rational structural design of the filler is needed to ensure the viable development of the composite material. Using reduced graphene oxide (RGO) as substrate, three-dimensional (3D) heterostructured reduced graphene oxide-hexagonal boron nitride (RGO-hBN)-stacking material was constructed by self-assembly of hBN nanosheets on the surface of RGO with the assistance of binder for silicone thermal grease. Compared with hBN nanosheets, 3D RGO-hBN more effectively improves the thermally conductive properties of silicone thermal grease, which is attributed to the introduction of graphene and its phonon-matching structural characteristics. RGO-hBN/silicone thermal grease with lower viscosity exhibits higher thermal conductivity, lower thermal resistance and better thermal management capability than those of hBN/silicone thermal grease at the same filler content. It is feasible to develop polymer-based thermal interface materials with good thermal transport performance for heat removal of modern electronics utilising graphene-supported hBN as the filler at low loading levels.

A facile method is designed to prepare 3D reduced graphene oxide (rGO) - carbon nanotubes (CNTs) - nickel foams (NF). In this research, the 3D rGO-CNTs-NF electrode is fabricated by combination of electrophoretic deposition and floating catalyst chemical vapor deposition. The vertically-aligned CNTs forests not only effectively prevent stacking of rGO sheets but also facilitate the electron transfer during the charge/discharge process and contribute to the whole capacitance. Moreover, the 3D rGO-CNTs-NF hybrid can be used directly as electrodes of supercapacitor without binder. Additionally, the hybrid shows a specific capacitance of 236.18 F g −1 which is much higher than that of the rGO - NF electrode (100.23 F g −1 ). Importantly, the energy density and power density of 3D rGO-CNTs-NF are respectively as high as 19.24 Wh kg −1 and 5398 W kg −1 , indicating that our work provides a way to design hierarchical rGO-based architecture composed of rGO, CNTs and various electroactive materials for high-performance energy storage devices.

The reduction of graphene oxide was promoted remarkably under pressure via low temperature thermal treatment. Traditionally, graphene oxide is usually reduced in a preheated high temperature environment as a precondition of the thermal reduction. We report a pressure promoted method for low temperature thermal reduction and exfoliation of graphene oxide in large quantity at 260 °C. The physicochemical properties of parent graphite, as well as the microstructure and physicochemical properties of graphene oxide and resultant graphene were investigated by Raman spectrometer, thermograviment analyzer (TGA), transmission electron microscope (TEM), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FT-IR). Results show that graphene oxide was reduced to graphene with less stack via low-temperature pressure promoted thermal treatment, meanwhile, the degree of disorder reduced: the ratio of ID/IG in Raman spectrum decreases from 0.64 to 0.56. Moreover, graphene derived from low-temperature pressure promoted treatment exhibit better thermal stability than graphene oxide, and oxygen functional groups were removed with a high level. All of results exhibit improved comprehensive properties than graphene synthesized via traditional thermal reduction at 1000 °C.

Graphene oxide can be used to prepared graphene oxide/poly(methyl methacrylate) composites as nanofiller by bulk polymerization. Then the graphene oxide/poly(methyl methacrylate) are treated to produce graphene/poly(methyl methacrylate), via low-temperature and pressure promoted thermal reduction process. The physicochemical properties and microstructure of graphene were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and thermograviment analyzer (TGA). The effects of low-temperature and pressure promoted thermal reduction graphene amount on the microstructure, mechanical strength, and pyrolysis properties of graphene/poly(methyl methacrylate) were investigated by scanning electronic microscopy (SEM), universal testing machine and TGA, respectively. It is found that the introduction of graphene oxide and reduction within matrix have a significant effect on the microstructure of polymer composites. The flexural strength and thermal stability of polymer composites increased with the increase of graphene additive amount, and it is better than the polymer composites which added graphene immediately, whose flexural strength the maximum is ca. 92 MPa.

Ferroferric oxide (Fe3O4)/functionalized multi-walled carbon nanotube (f-MWCNT) nanomaterials were synthesized by chemical deposition & hydrothermal method. Fe3O4/f-MWCNT composites possess the same ferrimagnetism as pure Fe3O4, and the composites will present certain orientation in magnetism. The saturation magnetization (Ms) is about 48.84 emu g−1 and the coercivity (Hc) is 19.19 Oe. The electrochemical analysis displays that the glassy carbon electrode coated with Fe3O4/f-MWCNT composite has a favorable promotion for the electrochemical response of H2O2. This process not only widely improved the redox current of H2O2, but also reduced the overpotential of redox process.

This paper describes the fabrication and characterization of a three-dimensional (3D) MnO 2 -graphene (GR)-CNT hybrid obtained by combining electrochemical deposition (ELD)-electrophoretic deposition (EPD) and chemical vapor deposition (CVD). Firstly, 3D MnO 2 -graphene oxide (GO) is fabricated via ELD-EPD. Secondly, the catalyst and xylene are mixed with solution of certain concentration. Thirdly, catalyst is loaded on the surface of MnO 2 -GO when the solution is sprayed into the furnace. Forth, MnO 2 -GO is restored to MnO 2 -GR at high temperature, meanwhile, MnO 2 -GR is served as a substrate to grow CNT, which is beneficial to provide high speed channel for carrier and obtain pseudocapacitance of MnO 2 . The as-prepared hybrid is characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray Diffraction (XRD) and Raman spectroscopy (Raman), and their supercapacitor properties are also investigated. The results show that a high specific capacitance of 330.75 F g −1 and high energy density of 36.68 Wh kg −1 while maintaining high power density of 8000 W kg −1 at a scan rate of 200 mV s −1 . Furthermore, the hybrid displays a high specific capacitance of 187.53 F g −1 at ultrahigh scan rate of 400 mV s −1 . These attractive results demonstrate that the hybrid is a promising electrode material for high performance supercapacitors.

Highly vertically aligned carbon nanotube arrays grown on the surface of pure titanium plates by chemical vapor deposition serve as substrates for electrodepositing polyaniline, thus fabricating three-dimensional carbon nanotube/polyaniline composites. In addition, X-ray diffraction and Raman spectroscopy are applied to investigate the structures of the as-prepared hybrids. Morphological analysis of the nanotube/polyaniline composites is performed by high resolution SEM and transmission electron microscopy. The combination of the three-dimensional carbon nanotube architecture and conducting polyaniline surprisingly generates a synergistic effect on electrochemical performance which is particularly important. Consequently, the vertically aligned carbon nanotube/polyaniline hybrids exhibit excellent characteristics in terms of specific capacitance (752.5 F g−1) and power density (5364 W kg−1) at a scanning rate of 100 mV s−1. Furthermore, the capacity retention can reach over 82% (after 10 000 cycles). This work highlights the critical role of the introduction of vertically laid carbon nanotubes with highly conducting polyaniline in improving the performance of supercapacitors.

Well-aligned carbon nanotubes (CNTs) with different shapes, namely coiled CNTs (CCNTs), V-shape CNTs (VCNTs) and ribbon-like CNTs (RCNTs), were prepared by floating catalyst chemical vapor deposition (FC-CVD) using triethylsilane and ferrocene as catalyst precursors and xylene as carbon source. The products were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and energy dispersive spectrometer. The experimental results indicated that triethylsilane limited the catalyst effectivity in the formation of the novel shapes. When the mole ratio of ferrocene and triethylsilane reached 10:1, the array morphology was maintained and several shapes appeared. It inferred that the catalyst particles were formed by two phases, namely Fe–C–Si solid solution and cementite Fe 3 C. The different absorption and desorption rates of carbon atoms between this two phases as well as the catalyst morphology change during the growth consequently lead to the formation of CCNTs and RCNTs. As for the VCNTs, it concluded that the partial inactivation of catalysts lead to two separated growth areas of CNTs which formed this CNTs. A mechanism is proposed to explain the relationships between the adding of triethylsilane and the formation of the novel structure.

Using lanthanum-doped graphene as nanofiller and poly(methyl methacrylate) as matrix, the electromagnetic shielding effectiveness and thermal stability of La-graphene/poly(methyl methacrylate) composites were studied. The temperature of maximum pyrolysis rate and electromagnetic shielding effectiveness of specimens obviously increased under low nanofiller loadings, whose peak value of shielding effectiveness is ca. 29 dB over the frequency range of 8.2–12.4 GHz.

PEGylation of nickel-zinc oxide nanorods (PEG-Ni-ZnONRs) composites was synthesized by a modified co-precipitation method and calcined at different temperatures to optimize their properties suitable for biomedical applications. The upshot of calcination on the properties of PEG-Ni-ZnONRs formulated, were analyzed using different characterization techniques via UV–Visible diffuse reflectance spectroscopy (DRS), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and energy dispersive X-ray (EDX) coupled with SEM analysis. The XRD analysis showed the hexagonal wurtzite crystal structure of PEG-Ni-ZnONRs; while the SEM analysis revealed the formation of enhanced nanorod after calcination of PEG-Ni-ZnONRs up to 700 °C. The antibacterial and antifungal activities of the enhanced properties of the formulated PEG-Ni-ZnONRs, were examined using Ager Well Diffusion Method (AWDM) against four bacterial and five fungal pathogenic strains with enhanced antibacterial and antifungal activities. It is noteworthy that after calcination, the morphology, structural and bandgap properties of PEG-Ni-ZnONRs were influenced and enhanced for biomedical applications.

This work reports the synthesis of PEGxMn0.5Zn0.5Fe2-xO4 NPs via sol–gel protocols using PEG to modify and evaluate their microstructural and magnetic properties for their potential use as thermoablation applications. The properties of the obtained samples were analyzed by XRD as a cubic spinel structure. The TEM analysis confirmed the spherical morphology of the sample with an average particles size of 15.7 ± 1.7 nm. The VSM shows the ferromagnetic nature of the samples. The self-healing ability of the sample was investigated, taking into account the physicochemical properties with the aim to determine the underlying utilization of the sample as thermoablation in hyperthermia application. The heating ability was reduced from 74 to 42 and the SAR reduced from 8.6 to 3.5 W/g to attain the Curie temperature within the therapeutic range. Based on the obtained results, the formulated PEGxMn0.5Zn0.5Fe2-xO4 NPs can be potentially used as thermoablation in hyperthermia applications.

In this work, carbon dot decorated copper sulphide/carbon nanotubes (CuS@CD-CNTs) composite with a unique three-dimensional (3D) grape string-like structure was directly prepared via in situ hydrothermal process at the temperature of 180 °C for 12 h and applied for supercapacitors. The chemical composition and morphology were systematically tested by XRD, Raman, SEM and TEM characterization techniques. The as-prepared CuS@CD-CNTs composite brings out a novel 3D grape string-like structure, where the CuS spheres are distributed homogeneously with CNTs as a result of the addition of carbon dot. As the active material of pseudocapacitor electrode, the CuS@CD-CNTs composite delivers superior electrochemical properties with a decent specific capacitance of 736.1 F g−1 at the current density of 1 A g−1. Also, the CuS@CD-CNTs composite showed exceptional cycling stability, maintaining 92% retention after 5000 charge-discharge cycles. Such superior electrochemical properties owe to the collective contribution of CuS, CD and CNTs and 3D grape string-like architecture. The excellent electrochemical results above suggest that CuS@CD-CNTs composite has promising electrochemical energy storage application in supercapacitors.

With developments of the electronics industry, more components are being included in electronic devices, which has led to challenges in thermal management. Using reduced graphene oxide embedded with MQ silicone resin (RGO/MQ) nano-aggregates as the composite filler and silicone rubber (SR) as the matrix, a simple approach is designed to prepare RGO/MQ/SR composites. Reduced graphene oxide (RGO) was first used as a substrate for the growth of MQ silicone resin by hybridization, forming sandwich-like micro structured RGO/MQ nano-aggregates successfully. Then, RGO/MQ was integrated into &alpha, &omega, dihydroxylpolydimethylsiloxane based on the in situ solvent-free blending method, followed by condensation and vulcanization, fabricating the final RGO/MQ/SR composites. The effective strategy could enhance the adaptability between graphene and silicone matrix under external stimuli at room temperature by embedding nanoscale MQ into the interface of graphene/silicone as the buffer layer. Obvious improvements were found in both thermal conductivity and mechanical properties due to excellent dispersion and interfacial compatibility of RGO/MQ in the host materials. These attractive results suggest that this RGO/MQ/SR composite has potential as a thermal interface material for heat dissipation applications.

In this study, a three-dimensional hybrid was synthesized via depositing of carbon nanotubes (CNTs) and ferroferric oxide (Fe3O4) particles on the abandoned disposable sheet mask fabric, followed by the polymerization of polypyrrole (PPY). The as-prepared nanocomposite shows superior electrochemical performances when it was used for the material for the flexible supercapacitor electrode. Benefiting from the synergistic effect of CNTs, Fe3O4 and PPY in such a porous structure, cyclic voltammetry and galvanostatic charge/discharge measurements indicated that the as-prepared hybrid possessed a good reversibility and high specific capacity at various scanning rates. It turned out that the as-prepared electrode demonstrated a high specific capacitance of 221.7[Formula: see text]F/g at the scanning rate of 50[Formula: see text]mV/s and long-life cycling stability of 88.2% after 10[Formula: see text]000 cycles. Besides, the electrode composite had good flexibility after repeated bending times of 3000. With the exception of improved electrochemical properties, this hybrid electrode material also showed many advantages, including facile preparation, flexibility and cost savings. These results will provide new ideas and solutions to design and fabricate the flexible supercapacitors, which has great prospect in the development of energy storage devices.

Large area multilayered graphene films were prepared by chemical vapour deposition using copper foils as substrate. We found that reaction temperature seriously affected the defects of the film but did not change the size, while reaction time dominated the defects and size. We further explained the surface deposition growth of the graphene film, and ascribed the growth of amorphous carbon to the reduction of copper catalysis. In addition, the graphene film showed improved electrocatalytic effect on hydrogen peroxide. This study opens an avenue for large area preparation of high quality graphene film for its electrochemical applications.

Highly aligned manganese dioxide (MnO2) nanowall arrays electrodeposited onto Ti sheets are used as substrates to grow graphene (GR) through chemical vapor deposition (CVD), thus forming a three-dimensional (3D) MnO2/GR hybrid composite. Furthermore, a 3D MnO2/GR hybrid with different structures and properties has been prepared at different temperatures. The as-prepared hybrid materials could be directly used as supercapacitor electrodes without any binder and conductive additive, and fully maintain the high conductivity and high specific area of GR, and large pseudocapacitance of MnO2 nanowall arrays. In aqueous electrolytes, the hybrids show a high specific capacitance of ∼326.33 F g−1 with good cycling stability at the scan rate of 200 mV s−1 and high energy density of 23.68 W h kg−1 while maintaining high power density of 7270 W kg−1. The preparation method provides a novel method to fabricate 3D graphene-based composite materials, and the as obtained hybrid electrode demonstrates its potential applications in supercapacitors.

The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self‐propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (< −10 dB). The 3D lamellar graphene structures could consume the incident waves through multiple Reflection and scattering within the layered structures, Prolonging the propagation path of electromagnetic waves in the absorbers.

Semiconducting single-walled carbon nanotubes (s-SWCNTs) were in situ synthesized by a temperature-controlled arc discharging furnace with DC electric field using Co–Ni alloy powder as catalyst in helium gas. The microstructures of s-SWCNTs were characterized using high-resolution transmission electron microscopy, electron diffraction, and Raman spectrometry apparatus. The experimental results indicated that the best voltage value in DC electric field is 54 V, and the environmental temperature of the reaction chamber is 600 °C. The mean diameter of s-SWCNTs was estimated about 1.3 nm. The chiral vector (n, m) of s-SWCNTs was calculated to be (10, 10) type according to the electron diffraction patterns.

An asymmetric supercapacitor was prepared on a sheet of filter paper with two modified surfaces acting as electrodes in 1 M potassium hydroxide aqueous solution. By choosing carbon nanotubes and two different kinds of metal oxides (zinc oxide and ferro ferric oxide) as electrode materials, the asymmetric supercapacitor was successfully fabricated. The results showed that this device exhibited a wide potential window of 1.8 V and significantly improved electrochemical performances of its counterparts. Particularly, the one-sheet asymmetric supercapacitor demonstrated high energy density of 116.11 W h/kg and power density 27.48 kW/kg, which was attributed to the combined action and shortened distance between the two electrodes, respectively. Besides, it showed superior electrochemical cycling stability with 87.1% capacitance retention under room temperature. These outstanding results can not only give researchers new insights into compact energy storage systems, but they also provide a good prospect for flexible asymmetric supercapacitors.

Although the dispersion of graphene oxide in solution has been well studied, there still exists mysteries. Here the graphene oxide was synthesized by the modified Hummers method. By the circle acid...

Multi-wall carbon nanotube/Fe3O4 hybrids were prepared by a chemical synthesis-hydrothermal treatment method and their electromagnetic wave absorbing properties were investigated in the frequency range of 8.2–12.4 GHz (X band). As-prepared hybrids were characterized by transmission electron microscopy, X-ray diffraction and vibrating sample magnetometer. Results indicated that the surface of multi-wall carbon nanotubes was attached to magnetic Fe3O4 nanoparticles. The Fe3O4 content increased and the magnetism of the hybrids was enhanced by increasing the concentrations of Fe2+ and Fe3+ in solution. The minimum reflection loss (−18.22 dB, 12.05 GHz) was the lowest and the absorbing bandwidth was the widest when the concentrations of Fe2+ and Fe3+ were 0.02 and 0.04 M, respectively. [New Carbon Materials 2013, 28(3): 184–190]

With the technological progress in the synthesis of multi-walled carbon nanotubes and single-walled carbon nanotubes, more attention was attracted to the synthesis of carbon nanotubes with diameter distribution, ideal length, different chirality and certain orientation. In recent decade, all these factors have been investigated and a number of progresses have been made for the application of carbon nanotubes. The latest researches on the growth of diameter-controlled single-walled carbon nanotubes are reviewed and discussed. The existing problems and challenges of the synthesis processes have been addressed in the future directions.

Using rare metal nitrate-doped multi-walled carbon nanotubes as the absorber and polyvinyl chloride as the matrix, the microwave electromagnetic and absorbing properties of multi-walled carbon nanotube/polyvinyl chloride composites were studied. The complex permittivity of the composites doped with different rare metal nitrate decreased in the frequency region of 8.2–12.4 GHz. The minimum reflection loss of rare metal nitrate-doped multi-walled carbon nanotube/polyvinyl chloride composites decreased and shifted slightly to the higher frequency region, and the absorption bandwidth (90%) increased in the frequency range of 8–18 GHz compared to multi-walled carbon nanotube/polyvinyl chloride composites. The reflection loss (3)3-doped multi-walled carbon nanotube/polyvinyl chloride composites is the widest from the absorption bandwidth (maximum is 5.12 GHz).

The design of double-layer structure could improve the absorbing properties of electromagnetic (EM) wave absorbing composites. Doping of rare metal (RM) could enhance the EM wave absorbing capability of the multi-walled carbon nanotubes (MWCNTs). In this paper, the polymer matrix composites with the different RM-doped MWCNTs and the pure MWCNTs as the absorber in the first and second layer respectively was fabricated (4 mm in thickness). The EM wave absorbing properties of these composites were studied. The results show all reflection loss curves of these composites have two absorption peaks in the frequency range of 2–18 GHz, and the reflection loss (