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Based on the increasing application requirements for the efficient adsorption of wastewater pollutants, graphene oxide-carbon nanotube/activated carbon (GO-CNT/AC) composites are constructed from the optimal microstructure matching of GO, CNTs, and AC materials by solution impregnation and freeze-drying methods. Three-dimensional structures with nano-micro hierarchical pores are established, with GO and CNTs uniformly dispersed on the AC surface, effectively restrain the agglomeration. The added CNTs played a "spring" role, supporting the gap between the GO sheets and AC matrix. Meanwhile, stable links are formed between GO, CNTs, and AC, realizing the synergistic matching of the microstructure, which provides abundant active absorption sites beneficial for improving the adsorption performance. The influences of the CNT contents, adsorbent amounts, methylene blue (MB) concentrations, and pH values on the adsorption property of GO-CNT/AC composites are systematically investigated. The results show that when the pH value of the MB solution is 13, the CNT concentration is 3 mg/mL and the MB concentration is 200 mg/L, the adsorption property of the composite is the best, with an adsorption capacity of 190.8 mg/g and a removal percentage of 95.4%. Compared with the raw AC, the adsorption capacity and removal percentage of the composites are increased by 73.9% and 72.8%, respectively. The GO-CNT/AC composites exhibit excellent cyclic adsorption performance, with a cyclic stability of 91.8% after six rounds of adsorption–desorption cycles. The kinetic analysis shows that the adsorption process conforms to the PSO kinetic model. By fitting of the IPD model, the adsorption mechanisms of the GO-CNT/AC composites are divided into two adsorption stages and described respectively. This study provides a new way to achieve highly efficient adsorption of pollutants in wastewater. [ABSTRACT FROM AUTHOR]

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 F/g at the scanning rate of 50 mV/s and long-life cycling stability of 88.2% after 10 000 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. A novel method of preparing the three-dimensional composite supercapacitor electrode was reported by using the abandoned disposable sheet mask paper as the substrate. The mixture of carbon nanotubes and ferroferric oxide particles were first uniformly deposited on the sheet mask cellulose fabric, followed by the polymerization of polypyrrole. It turned out that the as-prepared electrode not only showed excellent electrochemical properties, but also demonstrated good flexibility and low cost savings. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Electromagnetic wave absorbing properties of absorbing composites depend on the dielectric and magnetic loss generally. In this paper, using Fe3O4-coated amorphous carbon nanotubes (ACNTs-Fe3O4) fabricated using a chemical synthesis–hydrothermal treatment method as an absorber and polyvinyl chloride (PVC) as a matrix, electromagnetic and mechanical properties of ACNT-Fe3O4/PVC composite were investigated. The results showed that the dielectric and magnetic losses of ACNT-Fe3O4/PVC composite were significantly enhanced in 8.2–12.4 GHz compared to ACNT/PVC composite, which improved absorbing properties, while slightly changing the mechanical properties. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Graphene sheets are produced using multi-walled carbon nanotubes (MWCNTs) under different methods and with varying oxidant content, via oxidation and reduction process. Then the graphene sheets are further added into poly(methyl methacrylate) (PMMA) as nanofiller to produce composites. The physicochemical properties of MWCNTs, as well as the microstructure and physical properties of graphene sheets and composites were investigated by Raman spectrometer, thermograviment analyzer (TGA), transmission electron microscope (TEM), scanning electron microscope (SEM) and universal testing machine, respectively. The results show that the lengthwise opened degree of MWCNTs increase with the potassium permanganate content increasing, meanwhile, the process of multistep add (3:2:1) 600 wt.% potassium permanganate within 2 h is the appropriate procedure and content of oxidant. Moreover, the multistep added method contributes to oxidize equably and form completed graphene sheets as nanofiller. The structure, the thermal stability and mechanical properties of composites can be severely affected by the different type graphene sheets. Thus, it is critical to tailor modified the preparation method of graphene sheets for obtaining composites with high performance. [ABSTRACT FROM AUTHOR]

Abstract: By adding carbon nanotubes (CNTs) into medium temperature coal tar pitch, mesocarbon microbeads (MCMBs) were obtained via thermal condensation, then CNTs/MCMBs composites were in situ prepared using compression molding. The morphology, structure and mechanical properties of CNTs/MCMBs composites were characterized by optical microscope, digital camera, scanning electron microscope (SEM) and mechanical test machine. Results showed that CNTs were used as the nucleating agent and could inhibit the growth and coalescence of MCMBs. The optical textures of CNTs/MCMBs composites showed similar characteristics to the thermal condensation products from coal tar pitch with CNTs. The mass ratio of CNTs to coal tar pitch played an important role in the mechanical properties of CNTs/MCMBs composites. The density and bending strength of CNTs/MCMBs composite first increased and then decreased with the increase of the proportion of CNTs. When the proportion of CNTs was 5wt%, the density of the composite reached the maximum (1.76g/cm3). In addition, the bending strength of the composite reached the maximum (79.6MPa) as adding 2wt% CNTs into coal tar pitch. [Copyright &y& Elsevier]

Abstract: Composites that effectively absorb microwave in the frequency range of 2–18GHz have been strongly demanded during the past decades. To enhance the absorption of microwave, composites are generally capable of wide absorption bandwidth and low reflection loss. Here, we used La(NO3)3-doped multi-walled carbon nanotubes (MWCNTs) as absorber and polyvinyl chloride (PVC) as matrix to fabricate MWCNT-La(NO3)3/PVC composites, where La(NO3)3-doped MWCNTs broadened the absorption bandwidth and decreased the reflection loss of the composites. Due to the insertion of diamagnetic La3+, the absorbing properties of as-prepared composites were enhanced, while the mechanical properties of such composite were slightly changed. The amount of doped La(NO3)3 was experimentally optimized to be 6wt.%. [Copyright &y& Elsevier]

Abstract: 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 (4mm 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 2–18GHz, and the reflection loss (<−10dB) of the MWCNTs doped Ni is the widest from the absorption bandwidth (maximum is 5.28GHz), relatively. [Copyright &y& Elsevier]

Amorphous carbon nanotubes (ACNTs) were produced by a temperature-controlled arc discharging furnace with a mixture powders of Co-Ni (1:1wt%) alloy as catalyst and hydrogen as buffer gas. As-grown and treated ACNTs with a mean diameter of about 14nm for hydrogen storage and release experiments were studied in this paper. The test experiments of hydrogen uptake and release were carried out by a volumetric gas-adsorption measurement system. The results indicated that the hydrogen storage capacity of ACNTs was 1.1wt% at the pressure of 2.45MPa and room temperature. Around 50% of the adsorbed hydrogen gas of ACNTs could be released under a standard pressure and at room temperature. [ABSTRACT FROM AUTHOR]

Biocompatible multi-walled carbon nanotubes (MWCNTs)/chitosan(CS) composites were synthesized by electrostatic interactions between positively charged CS and negatively charged MWCNTs colloid solution functionalized with nitric and sulfate acid. The effect of pH value on the viscosity of MWCNTs/CS colloid could be controlled by adjusting the pH value, which was determined by the charge type and potential strength. The electrochemical properties of MWCNTs/CS composites were also studied by CHI650C electrochemical workstation. The MWCNTs/CS composites were characterized by using Fourier transform infrared spectrometer (FT-IR), High-Resolution Transmission Electron Microscope (HRTEM) and thermal gravimetric analysis (TGA). The experimental results showed that the stable and homogeneous MWCNTs/CS composites were obtained at pH 5 owing to existing strong electrostatic attraction. The weight ratio of CS polymer attached on the surface of MWCNTs was around 45wt%, and the thickness of CS grafted on the surface of MWCNTs was about 4nm. The electrocatalytic activity of nitrite (NO2-) decorated with MWCNTs/CS composites glass-carbon electrode was tested, and the results indicated that the MWCNTs/CS modified electrode possess excellent electrocatalytic ability. [ABSTRACT FROM AUTHOR]

Abstract: Carbon films with a well-developed meso-porosity were synthesized directly by the carbonization of sulfuric-acid-treated P123 triblock copolymer/silica nanocomposite films, which were prepared from dip-coating technique through an association of sol–gel and evaporation-induced self-assembly process, and the residual silica was removed subsequently via HF-etching. P123 was employed as both structuring agent for self-assembly of tetraethyl orthosilicate and carbon precursor. The sulfuric acid solution was used as a catalyst for cross-linking of P123/silica in order to improve the carbon yield for the continuity of carbon films. Investigations by Field emission scanning electron microscopy (FESEM), X-ray diffraction, nitrogen adsorption measurement and transmission electron microscopy (TEM) indicate that the hybrid carbon/silica mesoporous films are preserved perfectly after the carbonization. When the silica is removed by acid treatment, continuous carbon films with an ordered symmetric structure are still kept well. The carbon films obtained are composed of carbon nanotubes with the diameter of around 6nm, and the lengths of nanotubes affiliating with each other vary from about 100nm to several micrometers, which were measured by FESEM and TEM. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

The preparation of high performance, low cost and recyclable adsorbents is very important to cope with the increasingly devastating water pollution. As a typical three-dimensional porous carbon material, carbon foam (CF) is expected to be a highly efficient adsorbent to wipe out organic dyes from wastewater. However, the uneven size distribution, and lack of adsorption sites signified by insufficient foaming process limit its wider application in the environmental field. Here, CF/carbon nanotubes/graphene oxide (CF/CNTs/GO) composites (adsorbents) were prepared by press-assisted foaming and carbonization methods using mesophase precursors of coal tar pitch and CNTs followed by impregnation of GO nanosheets. The results highlighted that the addition of CNTs facilitated improvement in pore distribution, porosities, and mechanical properties (20 MPa). After treating with GO nanosheets, the adsorption performances of CF/CNTs/GO adsorbents substantially improved due to the increased active sites in the CF/CNTs and the adsorption rate and capacity of methylene blue (MB) reached 73.1% and 146 mg/g respectively. Further, adsorption isotherms (Langmuir and Freundlich), thermodynamics, quasi-first order and quasi-second order kinetics and intraparticle diffusion models were employed to investigate the adsorption mechanism. This work provides a low-cost fabrication technique for the high-performance CF/CNTs/GO adsorbent and is expected to provide reference for application in the treatment of contaminated water. [ABSTRACT FROM AUTHOR]

Abstract 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-C f /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-C f /SiC and C f /SiC, the flexural strength of CNTs-C f /PF/SiC increased by 15.27% and 51.95%. After heat treatment, the weight loss of CNTs-C f /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 C f /SiC composite. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotubes (CNTs) are synthesized by catalytic chemical vapor deposition (CCVD) from xylene, acetylene and their mixture. The addition of acetylene significantly increases the decomposition rate of xylene and decreases the benzene concentration in the effluent gas, as well as improving the quality of the CNTs obtained. There is a strong interaction between acetylene and xylene during the CCVD process. Various chemical components at different positions of the CVD reactor are classified and identified by mass spectrometry. Reaction kinetics constants are determined numerically based on the in situ measurement. Chemical kinetics of CCVD process is analyzed based on a detailed mechanism (88 species and 322 reactions), which successfully demonstrates the decomposition of the used carbon sources, and the synergistic effect of the addition of acetylene. The generation of hexagonal carbon rings from the dehydrogenation of benzene rings is described and discussed combined with the formation of CNT structures. [ABSTRACT FROM AUTHOR]

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 NiCo 2 S 4 (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 NiSO 4 ·6H 2 O 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. Schematic illustration of the fabrication process for the r-GO/a-CNT/NCS. Image 1 • Different concentration of pure NCS causes various microstructure and properties. • The addition of a-CNT and r-GO can greatly improve the EM absorption properties. • The maximum frequency bandwidth is 5.1 GHz below −5 dB. • The maximum absorption peak is −35.8 dB at 8.1 GHz. [ABSTRACT FROM AUTHOR]

Fabrication of highly elastic three-dimensional aerogel adsorbents with outstanding adsorption capacities is a long pursuit for the treatment of industrial contaminated water. In this work, a magnetic reduced graphene oxide (rGO)/Fe 3 O 4 /carbon nanotubes (CNTs) aerogel material was constructed by the electrostatic attraction between the negatively charged GO and positively charged CNTs following a one-pot water bath treatment. The as-synthesized aerogel demonstrated high compressive stress (28.4 kPa) and lower density (24.11 mg/cm3) with exceptional adsorption capacities for versatile adsorbates which are attributed to CNTs and magnetic Fe 3 O 4 nanoparticles. The effect of pH, initial concentration of adsorbates (dyes, Cd (ІІ) ions, organic solvents, and pump oil), content of CNTs and cyclic times on the adsorption capacities of the aerogel were investigated in detail. Furthermore, from simulation, the adsorption kinetics, and thermodynamics of the aerogel for adsorbates were more satisfied by endothermic quasi-second-order kinetic model with characteristic physical adsorption. Thus, the optimized rGO/Fe 3 O 4 /CNTs-10 aerogel adsorbent can be used as a powerful and versatile tool to deal with contaminated industrial or domestic wastewater. [Display omitted] • Aerogel was fabricated via electrostatic attraction and subsequent one-pot water. • Magnetic rGO/Fe 3 O 4 /CNTs aerogel with high mechanical stability was fabricated. • Aerogel achieved outstanding adsorption capacity for versatile adsorbates. • The produced aerogel demonstrated an almost 100% initial adsorption capacity. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

Amorphous carbon nanotube (ACNT)/sulfur composites were prepared by solution reaction method. The electrochemical results showed that both ACNT/S composite and ACNT/S mixture had a first reversible capacity of 1020 mA h·g −1 , and the capacity retention of ACNT/S composite was 77% after 100 cycles while that of ACNT/S mixture was only 35% with the initial capacity being 850 mA h·g −1 . The experimental results showed that the reversible lithium insertion capacity of the composite was obviously high and the cycling stability was good, which was mainly due to the solid and uniform dispersion of the sulfur and amorphous carbon nanotube matrix in the composite. [ABSTRACT FROM AUTHOR]

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)/BaFe 12 O 19 (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. [ABSTRACT FROM AUTHOR]

Homogeneous amorphous carbon nanotube (ACNT) networks have been synthesized using floating catalyst chemical vapor deposition method on a 3D graphene aerogel (GA)/ BaFe 12 O 19 (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. [ABSTRACT FROM AUTHOR]

A novel silicon core/amorphous carbon nanotube (ACNT) shell composite that can be used as lithium-ion batteries anode material was in-situ synthesized in the chemical vapor deposition (CVD) growth process. The hypothesized core/shell structure was evidenced by SEM/TEM/XRD, suggesting that the ACNTs composed of carbon clusters with short-range order and long-range disorder were successfully deposited onto the surface of the silicon particles. This Si/ACNT composite delivered a high capacity of 1496 mAh g −1 at a current density of 100 mA g −1 , and a superior cycling stability with 80% capacity retention after 300 cycles. This observed specific capacity improvement of Si/ACNT composite is likely attributed to the formed three-dimensional conductive networks between silicon particles and interwoven ACNTs in the composite. [ABSTRACT FROM AUTHOR]

Aligned amorphous carbon nanotube (AACNT)/BaFe 12 O 19 nanorod (BNR) composite was prepared by chemical vapor deposition and ball-milling methods. Raman and XRD tests were performed to investigate the microstructures, and the microwave absorbing properties of the as prepared composite were characterized using a vector network analyzer. The experimental results indicated that the mean length of as-prepared ACNT arrays was about 24 μm and the average length of BNRs were about 50 nm. The maximum absorbing peak of AACNTs/BNR composite is −21.5 dB at the frequency of 9.3 GHz. The frequency bandwidth of the reflectivity loss below −10 dB is about 2.5 GHz. AACNTs have both features of amorphous CNTs which have multiple-reflective path inside the tube-wall and crystalline CNTs which have high conductivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti 3 C 2 /Carbon Nanotubes/MnCo 2 S 4 composite electrode was fabricated by the rational design. • Micro-/nano-porous CNTs/MnCo 2 S 4 structure with high conductivity in the Ti 3 C 2 based electrode was formed. • The electrode has a high rate retention and excellent cycling stability. • As-synthesized Ti 3 C 2 /CNTs/MnCo 2 S 4 -0.5 electrode-based symmetric supercapacitor demonstrates a high-energy storage. The enhancement of electrochemical performance of supercapacitors with high-energy storage is largely determined by the selective electrode materials and their rational structural design. In this paper, we fabricated Ti 3 C 2 /CNTs/MnCo 2 S 4 composite electrodes by electrostatic self-assembly between positively charged multiwalled carbon nanotubes (CNTs) and negatively charged Ti 3 C 2, followed by subsequent anchoring of bimetallic sulphide MnCo 2 S 4 nanoparticles to Ti 3 C 2 /CNTs hybrid via a two-step hydrothermal method. All the Ti 3 C 2 /CNTs/MnCo 2 S 4 composite electrodes exhibit enhanced specific capacitance comparing with the pure Ti 3 C 2 electrodes. The optimized Ti 3 C 2 /CNTs/MnCo 2 S 4 electrode shows paramount gravimetric capacitance (C s) (823 F/g at a current density of 1A/g), high rate retention (63.5% of specific capacitance retains when current density increases from 1 to 5A/g), and excellent cycling stability (94.09% after 5000 charging and discharging cycles). These improved electrochemical performances are mainly attributed to the synergistic effect of high specific capacitance from the pseudocapative material of MnCo 2 S 4 , remarkable conductivity of Ti 3 C 2 and CNTs, and the micro-/nano-porous structures constructed by stacking Ti 3 C 2 flakes with CNTs. Moreover, the as-synthesized Ti 3 C 2 /CNTs/MnCo 2 S 4 electrode-based symmetric supercapacitor demonstrates a high energy density of 49.5 Wh/kg at a power density of 350 W/kg, suggesting that the electrochemical performance of Ti 3 C 2 -based supercapacitors can be substantially boosted by rational design and modification of Ti 3 C 2 electrodes with MnCo 2 S 4 and multilayer CNTs. [ABSTRACT FROM AUTHOR]

The improved physicochemical immobilization and catalytic redox conversion of lithium polysulfides (LiPSs) intermediates are considered to be a desirable solution to enhance the sulfur electrochemistry in lithium-sulfur (Li–S) batteries. Herein, we for the first time, reported the fabrication of the core-shell structure composed of cobalt-doped carbon nano-tube (CNT) assembled polyhedron core derived from the cobalt metal-organic frameworks (Co-MOFs)@graphitized porous carbon aerogel shell as the sulfur reservoir material for Li–S batteries. The obtained sulfur cathodes exhibited excellent electrochemical performance, including a high reversible capacity (939.9 mAh g−1 at 0.1C), outstanding areal capacity (3.35 mAh cm−2 after 50 cycles, under a low electrolyte/8.3 μL m g s − 1 ), and superior cycling stability (the capacity decay rate of 0.087% per cycle after 500 cycles at 1C). The improvement in electrochemical performance could be attributed to the unique core-shell architecture: the multiple polyhedron Co–C cores not only provide a multiple-point catalytic center for LiPS conversion, but also serves as the polar material to inhibit the migrating of polysulfides by chemical interaction; More importantly, the graphitized porous carbon aerogel shell provides a fast transport channel for Li+/e− diffusion, and also sufficient free space for the sulfur reservoir and Li 2 S 2 /Li 2 S deposition. [Display omitted] • Co–C polyhedra reduced the formation of non-graphitic carbon in carbon aerogel. • Core-shell structures provided adequate accommodation capacity for sulfur species. • Multipoint Co–C polyhedron cores accelerated polysulfide redox reaction kinetics. • The S/Co-GC@GPCA cathode delivered outstanding cycling stability. [ABSTRACT FROM AUTHOR]

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. Image 1 • The CuS@CD-CNTs composite with a peculiar 3D grape string-like structure is synthesized by hydrothermal reaction. • The synergistic effect of CuS, CD and CNTs is beneficial for electrochemical performance. • The 3D CuS@CD-CNTs composite shows high capacitance and stable cyclic performance. [ABSTRACT FROM AUTHOR]