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Graphene fibers (GFs) have a bright future in a variety of applications ascribing to their excellent performance. However, strict preparation conditions with extremely high graphitization temperature or toxic chemical reagents severely restrict their extensive implementation. Meanwhile, researchers are seeking easily scalable and eco-friendly GFs production methods. Here, we propose a green two-step reduction strategy involving L-ascorbic acid (LAA) chemical reduction followed by low-temperature annealing for the preparation of high-performance GFs. Benefiting from the elimination of macro-, micro- and nano-scaled defects and recombination of graphene nanosheets, the prepared GFs demonstrated amazing tensile strength of 778.49 MPa, Young's modulus of 92.61 GPa and an outstanding electrical conductivity of 3.2 × 104 S m−1, outperforming most of the chemically reduced GFs. This two-step green reduction strategy provides a new insight for constructing integrated high-performance GFs for sustainable application in many fields. [ABSTRACT FROM AUTHOR]

Defect engineering exerts a crucial impact on polarization loss and thereby enhances electromagnetic (EM) wave absorption ability. The EM loss mechanism beneath of morphology conversion is usually vaguely considered as the synergism of multiple mechanisms. Morphology induced defects and its dominated polarization loss mechanisms are little focus on. In this work, MnO 2 /Carbon foam (MCF) composites with tunable morphology were prepared via facile hydrothermal and annealing process. Morphological conversion of MnO 2 and its induced defects were achieved by KMnO 4 concentration, which contributes to the reduction of conductive loss, optimization of impedance matching, increase of polarization loss and multiple scattering. Therefore, the minimum reflection loss of MCF composite harvests −65.18 dB at 3.19 mm and the broad effective absorption bandwidth covers the entire X band. Despite multiple dissipation mechanisms, the excellent performance is dominated by morphology modulated defects in MCF composites. Besides, the optimal MCF composite displays a high compressive strength of 14.647 MPa. According to the results of computer simulation technology, the MCF composite can attenuate EM energy in the actual condition. This work is expected to offer an inspired understanding of morphology modulated defects toward high-performance of EM wave absorption materials. [Display omitted] • MnO 2 /CF with diversed morphologies and defects were rely on the content of KMnO 4. • Morphological evolution changed carbon defect, oxygen vacancy and lattice defects. • Effective absorption bandwidth of 4.2 GHz and reflection loss of −65.18 dB were achieved. • Defect deduced polarization loss can effectively enhance MA performance. • The RCS contribution of MnO 2 /CF composites in far field was calculated by CST. [ABSTRACT FROM AUTHOR]

Superpixel decomposition could reconstruct an image through meaningful fragments to extract regional features, thus boosting the performance of advanced computer vision tasks. To further optimize the computational efficiency as well as segmentation quality, a novel framework is proposed to generate superpixels from the perspective of hybridizing two existing linear clustering frameworks. Instead of conventional grid sampling seeds for region clustering, a fast convergence strategy is first introduced to center the final superpixel clusters, which is based on an accelerated convergence strategy. Superpixels are then generated from a center-fixed online average clustering, which adopts region growing to label all pixels in an efficient one-pass manner. The experiments verify that the integration of this two-step implementation could generate a synergistic effect and that it becomes more well-rounded than each single method. Compared with other state-of-the-art superpixel algorithms, the proposed framework achieves a comparable overall performance in terms of segmentation accuracy, spatial compactness and running efficiency; moreover, an application on image segmentation verifies its facilitation for traffic scene analysis. [ABSTRACT FROM AUTHOR]

The drawbacks of single loss capability and skin effect severely impede the electromagnetic (EM) wave absorption performance of carbon-based materials. Developing a rational hierarchical structure with high efficiency and facile method to optimize impedance matching and improve EM wave absorption performance still remains challenge. Herein, SiC nws /carbon foam (SCF) composites with hierarchical structure, were successfully prepared by chemical vapor deposition method. The core shell structure of SiC nws @SiO 2 was grown on the scaffold and inside of the cell structure in CFs. Significantly, the amount of SiC nws can be modulated by the growth temperature. Benefiting from the impedance gradient structure, coupled with interface polarization dominated loss mechanism jointly promoted the excellent EM wave absorption performance. Specifically, when the growth temperature is 1400 °C, the SCF composite achieved an optimal reflection loss value of −55.8 dB at 10.30 GHz with a thickness of 4.35 mm and a wide effective absorption bandwidth of 3.97 GHz at 3.71 mm. Meanwhile, in-situ growth of SiC nws in CFs substantially increased the compressive strength to 21.08 MPa. This work paves a new avenue to develop highly efficient EM wave absorption materials with hierarchical structures. [Display omitted] • The hierarchical core-shell SiC nws @SiO 2 -carbon foam hybrid composites were prepared by a facile CVD method. • SiC nws in-situ grown in CFs endowed composites well impedance matching. • The EAB of 3.97 GHz and RL min of −55.80 dB were achieved. • The enhanced EM wave absorption mechanisms were investigated in detail. [ABSTRACT FROM AUTHOR]

Graphene fibers (GFs), assembled from graphene-based building blocks, have received considerable attention both from academia and industry due to their intriguing features of high specific surface area, lightweight, easy functionalization, excellent mechanical, electrical and thermal properties. Herein, we have summarized current research status of GFs in terms of their latest fabrication techniques, characterization methods and reduction processes. Wet and dry spinning, dimension-confined hydrothermal strategy, electrophoretic self-assembly, and film conversion fabrication techniques are mainly discussed to optimize the best fabrication conditions. Moreover, various characterization techniques and reduction processes of GFs are also elaborated in detail. Finally, a perspective of the future development and applications of GFs have been given a separate portion in this review. [ABSTRACT FROM AUTHOR]

A flexible core-sheath structural Ti 3 C 2 T x MXene@polyaniline fiber electrode was fabricated through surface engineered covalent bridging strategy via wet spinning and in situ oxidant-free polymerization processes. The fiber achieved an ultrahigh tensile strength because of the high-order core-sheath structure and strong Ti-O-N covalent bonds between MXene and PANI. The assembled SC realized much higher volumetric capacitance due to the rapid electron conduction of core and large pseudocapacitive charge transfer of the sheath. [Display omitted] • A flexible MX@PA fiber was fabricated by wet spinning and oxidant-free polymerization processes. • An ultrahigh tensile strength and super-toughed fiber electrode was achieved. • Assembled SCs realized an ultrahigh volumetric energy density and good tensile strength. • Assembled SCs delivered an excellent volumetric energy density of 56.1 mWh cm−3 at a power density of 204.9 mW cm−3. MXene fiber-based supercapacitors (SCs) are expected to make a major contribution to the ongoing development of wearable electronics and metaverse technologies in future. However, to fabricate fiber electrodes with high energy density and strong mechanical properties remains a major challenge for their usage in SCs. Herein, we fabricated a flexible core-sheath structural Ti 3 C 2 T x MXene@polyaniline (MX@PA) fiber electrode with ultrahigh volumetric energy density and good tensile strength through surface engineered covalent bridging strategy via wet spinning and in situ oxidant-free polymerization processes. Benefiting from the high-order core-sheath structure and strong Ti-O-N covalent bonds between MXene and PANI, an ultrahigh tensile strength (∼168.1 MPa) and super-toughed (∼1.75 MJ cm−3) fiber electrode was achieved. The assembled SC provided much higher volumetric capacitance of 631F cm−3 (based on the SC device) at a current density of 0.5 A cm−3 and ultralong-term cycling stability with 92.6 % capacitance retention after 10000 cycles due to the rapid electron conduction of core (MXene) and large pseudocapacitive charge transfer of the sheath (PANI). As a result, the SC delivers excellent volumetric energy density of 56.1 mWh cm−3 at a power density of 204.9 mW cm−3. The integrated SC found actual application to power a 2.5 V red LED. [ABSTRACT FROM AUTHOR]

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 view of the good adsorption properties of graphene and carbon foam, they were combined to achieve the optimal matching of microstructures. Taking mesophase pitch as a raw material, pitch-based carbon foam was prepared by the self-foaming method. Graphene gel was prepared as the second phase to composite with the carbon foam matrix; graphene-modified, pitch-based carbon foam composites were finally obtained. Graphene gel was dispersed in the rich pore structure of carbon foam to improve its agglomeration and the porosity, and the active sites of the composite were further increased; the adsorption properties and mechanical properties of the composites were also significantly improved. The microstructure and morphology of the composites were studied by SEM, XRD and Raman spectroscopy; the compressive property and porosity were also tested. Methylene blue (MB) solution was used to simulate a dye solution for the adsorption test, and the influence of the composite properties and MB solution on the adsorption property was studied. Results showed that the compressive strength of the composite was 13.5 MPa, increased by 53.41%, and the porosity was 58.14%, increased by 24.15%, when compared to raw carbon foam. When the mass of the adsorbent was 150 mg, the initial concentration of the MB solution was 5 mg/L, and the pH value of the MB solution was 11; the graphene-modified carbon foam composites showed the best adsorption effect, with an adsorption rate of 96.3% and an adsorption capacity of 144.45 mg/g. Compared with the raw carbon foam, the adsorption rate and adsorption capacity of the composites were increased by 158.18% and 93.50%, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lightweight carbon foam bulk with controllable graphitization degree were prepared. • The regulation of dielectric loss based on the graphitization degree was proposed. • The EAB of 3.63 GHz, EMI SE of 35.13 dB, and strength of 11.73 MPa were achieved. • The interfacial polarization between graphite/amorphous carbon exists in the polarization loss. The graphitization degree is of great importance for determining the electromagnetic (EM) wave attenuation loss behavior. The conductive loss is considered to be the mechanism resulting from tailoring the graphitization degree. There is a lack of in-depth research on the dipole polarization caused by defects and functional groups and the interface polarization caused by graphite/amorphous carbon. Herein, lightweight carbon foam (CF) bulk derived from mesophase pitch was prepared to clarify the effect of the graphitization degree systematically. The results demonstrate that with an increase graphitization degree, the interfacial polarization improves and dipole polarization decreases. The synergistic effect of conduction loss and dipole and interfacial polarization dominates the impedance matching and further changes the EM loss behavior of CFs. Particularly, the minimum reflection loss is − 16.69 dB and effective absorption bandwidth is 3.63 GHz, the EM interference shielding effectiveness attains 35.13 dB and the compressive strength is up to 11.73 MPa when the optimal graphitization degree is achieved. Therefore, this work elucidates the effect of the interface polarization of graphite/amorphous carbon, thus providing a valuable insight into the design of advanced carbon-based materials for EM wave absorption and shielding. [ABSTRACT FROM AUTHOR]

A multifunctional MXene fiber was fabricated by incorporating MoO 3-x nanobelts with abundant oxygen vacancies via wet spinning and coagulation process, where the produced fiber not only realized the substantially improvement of volumetric capacitances, but also demonstrated a low limit of detection for biomarkers in artificial sweat. [Display omitted] • A multifunctional MXene/MoO 3-x fiber was fabricated by wet spinning and coagulation methods. • Fiber realized an ultrahigh volumetric energy density after the addition of treated MoO 3-x nanobelts. • Fiber demonstrated a low limit of detection for biomarkers in artificial sweat. • Fiber provided the potential applications in the next generation of wearable intelligent devices. MXene fibers are expected to accelerate the sustainable development of intelligent era as multi-functional smart fibers. However, MXene fibers have serious obstacles when used for multi-functional applications. Here, we fabricated a multi-functional MXene fiber by incorporating MoO 3-x nanobelts with abundant oxygen vacancies via wet spinning and defect engineering methods. Benefiting from the presence of abundant oxygen vacancies, the produced MXene/MoO 3-x fibers not only provide more active sites to interact with electrolyte ions, but also substantially augment the rate capacities of fibers due to the enlarged distances between MXene flakes. Thus, the assembled fiber-based supercapacitor (SCs) realized high capacitance of 869.1F cm−3 at 0.5 A cm−3, good volumetric energy density of 77.3 mWh cm−3 at a power density of 204.8 mW cm−3 and long-term cycling stability along with 86.4 % capacity retention after 5000 cycles. Moreover, due to the narrowed bandgap of MoO 3-x produced by defect engineering enhanced the charge transfer between the fiber and molecules, MXene/MoO 3-x fiber also demonstrated a low limit of detection and reliable biomarkers detection in artificial sweat. These findings provide the potential application of MXene-based fibers in multi-functional devices. [ABSTRACT FROM AUTHOR]

Summary: In recent 20 years, electronic equipment has been developing rapidly in the direction of light, miniaturization, flexibility, and integration. It is urgent to meet the needs of matching energy supply system to solve the practical application requirements in the fields of intelligent communication and mobile medical treatment. Electroactive polymers (EAPs) are recommendable material for manifesting muscle‐like actuation. The dielectric elastomers (DEs) obtained from the EAPs are quite capable of inducing electrical energy and transmute it into mechanical energy. DEs are capacitors covered by an outer elastic membrane, sandwiched between the two docile electrodes. In the beginning, for getting the efficient responses out of the DE actuators, the material requirements and electromechanical principal are applied. Viscoelastic damping, low dielectric loss, stretch ability, and dielectric permittivity are the desirable characteristics that we are expecting in a polymer. In the current research, we are going to adopt the sequential approach by describing the advances, challenges, and applications of DEAs in the coming future. [ABSTRACT FROM AUTHOR]

Sensitive and rapid identification of volatile organic compounds (VOCs) at ppm level with complex composition is vital in various fields ranging from respiratory diagnosis to environmental safety. Herein, we demonstrate a SERS gas sensor with size-selective and multiplexed identification capabilities for VOCs by executing the pre-enrichment strategy. In particular, the macro-mesoporous structure of graphene aerogel and micropores of metal-organic frameworks (MOFs) significantly improved the enrichment capacity (1.68 mmol/g for toluene) of various VOCs near the plasmonic hotspots. On the other hand, molecular MOFs-based filters with different pore sizes could be realized by adjusting the ligands to exclude undesired interfering molecules in various detection environments. Combining these merits, graphene/AuNPs@ZIF-8 aerogel gas sensor exhibited outstanding label-free sensitivity (up to 0.1 ppm toluene) and high stability (RSD=14.8%, after 45 days storage at room temperature for 10 cycles) and allowed simultaneous identification of multiple VOCs in a single SERS measurement with high accuracy (error < 7.2%). We visualize that this work will tackle the dilemma between sensitivity and detection efficiency of gas sensors and will inspire the design of next-generation SERS technology for selective and multiplexed detection of VOCs. [Display omitted] • A powerful graphene/AuNPs@ZIF-8 SERS gas sensor was fabricated. • Hierarchical pores greatly improve the enrichment efficiency of VOCs. • Pore size in sensor can be facilely adjusted for size-selective detection. • Sensor exhibited outstanding label-free sensitivity and high stability. [ABSTRACT FROM AUTHOR]

A flexible graphene oxide/Au nanoparticles (GO/AuNP) based fiber with high sensitivity and reproducibility for SERS sensing on a large scale using the self-assembly of liquid crystalline and wet spinning processes, which break the geometric limitations of the nanoscale of GO nanosheets and extend its properties to the macroscopic level. [Display omitted] • Uniform encapsulation of AuNPs in GO fiber by electrostatic adsorption and liquid crystal self-assembly process. • Extending GO/AuNPs hybrids nanoscale properties to the macroscopic level to address geometric constraints. • SERS sensitivity of the sensor derives from the synergistic effect of CT resonance of GO and plasmonic coupling of AuNPs at vertical direction. • Flexible GO/AuNPs fiber allow sampling on the peel surface for rapid detection of thiram residues. Graphene oxide has attracted wide interest for theoretical research and application exploration in surface enhancement Raman scattering (SERS). However, how to break the geometric limitations of the nanoscale and extend its properties to the macroscopic level remains an urgent problem. Here, we prepared flexible graphene oxide/Au nanoparticles (GO/AuNP) fibers with high sensitivity and reproducibility for SERS sensing using wet spinning method. Benefitting from the plasmonic coupling of GO/AuNP fibers in vertical direction and uniform adsorption of the target molecules, the limit of detection for fiber was as low as 5 × 10-11 M for rhodamine 6G (R6G) and crystal violet (CV) molecules. In addition, due to the optimal distribution of AuNP in the macroscopic assembly of GO/AuNP hybrid, the fiber substrates provided uniform and stable signals for both temporal (6 months) and spatial (RSD = 8.18 %) scales, exhibited excellent reliability and durability. Moreover, an ultra-low concentrations of the pesticide thiram residues could be rapidly traced by direct sampling from the apple peel with a sensitivity of 5 × 10-9 M, which is much lower than the residue limit set by the US environmental protection agency. We envision that this work could provide new insights into the large-scale and economical fabrication of high-performance flexible SERS sensors for real world applications. [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]

Summary: Polymeric carbon nitride (PCN) is a promising hotspot metal‐free material for artificial photosynthesis, solar energy conversion, and photo degradation of pollutant, hence predicting unsatisfactory photocatalytic efficiency due to fast charge recombination. Here, we implemented a remediation approach to fuel its catalytic performance by interpretation of a sulfur rich‐material, ie, trithiocyanuric acid (TTCA) in the framework of PCN by traditional one facile protocol called copolymerization (molecular assembled) under nitrogen at 550°C. Results demonstrate that the integration of TTCA comonomer into the triazine oligomers of PCN widens the specific surface area, extends the lifetime of photoexcited charge carriers, speeds up the rate of photogenerated electrons optimized from lower energy state toward high energy state, lowers the rate of charge recombination and band gap, and modulates its electronic structure and optical properties in a regular fashion as compared with pristine PCN. Ultimately, due to aforementioned modification, the copolymerized PCN semiconductor predicts superior photocatalytic properties of hydrogen energy production about 7 times higher than that of pristine PCN from the water splitting system. [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]

Abstract In this work, reaction bonded silicon carbide (RBSC) brake composites reinforced by chopped carbon fibers (CCFs) were fabricated by pre-liquid dispersion (PLD), low-temperature compression molding (LTCM) and subsequent densification by liquid silicon infiltration (LSI). The effects of the CCF fraction and PLD process on microstructure, phase composition, compression strength, shear strength and tribological performance of the brake composites were evaluated in detail. Our results showed that the distribution of CCF within the brake composites can be improved substantially through the treatment of PLD process, leading to the lowest open porosity of 9.63% and highest buck density of 1.87 g/cm3 comparing to the composites without PLD. Meanwhile, due to the augment of the interfacial area between the CCF and matrix, the as-prepared brake composite with 20 vol% CCF showed a compression strength as high as 157.55 MPa and shear strength of 22.14 MPa. Moreover, after further graphitization, a highly reliable RBSC brake composite with suitable average friction coefficient (0.427) for braking was obtained via the synergistic effects of lubrication of formed graphite and grain-abrasion by SiC grains in spite of a relatively high mass wear rate. These results show that the CCF reinforced RBSC brake composite is a promising candidate for high performance and low-cost friction composite for the application in brake pads. [ABSTRACT FROM AUTHOR]

Recently, ceramic matrix composites reinforced by short carbon fibers (CFs) attracted increasing attentions. To further improve mechanical properties and oxidation resistances, CFs were subjected to oxidation and acidification followed by sol-gel dip-coating to deposit ZrO 2 on their surfaces. ZrO 2 -C f /SiC composites were fabricated by joint hot compression molding and sintering, compared to C f /SiC and SiC prepared by the same method. Microstructural analyses indicated that ZrO 2 coatings were successfully deposited on CF surfaces, formed strong bonding and interfaces between CF and the matrix. Meanwhile, CFs were found uniformly distributed in SiC matrix with random orientations. Flexural curves of ZrO 2 -C f /SiC and C f /SiC revealed the presence of “false plasticity” regions after sharp drops, which were quite different from brittle flexural behavior of SiC ceramic. Compression strength of the three samples showed step-up growth. ZrO 2 -C f /SiC exhibited the highest value, indicating the introduction of CFs and ZrO 2 coatings do have great influence on mechanical performances. After heat treatment, ZrO 2 -C f /SiC exhibited better oxidation resistance than C f /SiC, with weight loss ratios estimated to − 3.76% and − 6.43%, respectively. These improved properties indicated that ZrO 2 -C f /SiC would be excellent alternatives to other existence materials under ultra-high temperature environments. [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]

In this paper, a facile method is designed to fabricate three-dimensional (3D) graphene (GR)/manganese dioxide (MnO2) nanowall electrode material. The 3D GR/MnO2 hybrid is prepared by a combination of electrochemical deposition (ELD) and electrophoresis deposition (EPD), followed by thermal reduction (TR). Firstly, the 3D graphene oxide (GO)/MnO2 hybrid is obtained by the ELD-EPD method. Secondly, the 3D GR/MnO2 hybrid is obtained through hydrogen reduction at a certain temperature. The as-fabricated hybrid has been characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy. The electrochemical properties have been also measured by cyclic voltammetry. The results showed that the 3D GR/MnO2 nanowalls hybrid has a high specific capacitance of 266.75Fg and a high energy density of 25.36Whkg. Moreover, a high specific capacitance (240.15Fg) at a high scan rate of 200mVs (90% capacity retention) has been also obtained. Additionally, the hybrid can serve directly as the electrodes of supercapacitor without adding binder. This work provides a novel road to fabricate a binder-free 3D GR-based hybrid for high-performance energy storage devices. 3D RGO-MnO2 hybrid has been successfully obtained by a combination of electrochemical deposition and electrophoresis deposition, followed by thermal reduction. The as-prepared 3D RGO-MnO2 hybrid proved its potential applications in electrochemical supercapacitors, besides the facile method and controllable structure may provide its use in large scale production and application. [ABSTRACT FROM AUTHOR]

This work presents a simple approach to produce controlled mullite whisker network structure. Mullite whisker networks were facilely prepared by direct sintering of coal fly ash, bauxite and kaolin in BaCO 3 -potash feldspar-pyrolusite-talcum catalytic system at 1350 °C. Controlled mullite whiskers were obtained with about 200 nm in diameter and 3 μm in length by controlling the rate of Al 2 O 3 diffusion through feldspar addition in catalytic system. Morphology evolution process and growth characteristics of mullite whisker networks were further investigated using scanning electronic microscope (SEM) and their possible fabrication mechanism were also investigated. The optimum mullite whisker network structural material exhibits some attractive properties such as high strength (199.89 MPa), low density (1.51 g cm −3 ) and low acid solubility (2.63 wt%). These results demonstrate an effective method to prepare large-scale mullite whisker network with potential applications in producing ceramic proppants. [ABSTRACT FROM AUTHOR]

C f /Ti 3 SiC 2 -SiC composites with different content of short carbon fibers were fabricated by the combination of compression molding and pressureless sintering. Microstructure and mechanical behavior of the composites were studied to evaluate the comprehensive performance of the material. In comparison, composites without carbon fibers were also fabricated in the same way. The results indicate that Ti 3 SiC 2 phases were synthesized in each cases and exhibit typical laminated structure with smooth surface. With the increase of carbon fiber content, composites turn from brittle to toughness, and show obvious elastic and no-linear regions on the force-displacement curve. Moreover, composite with 30% (volume fraction) carbon fiber shows the highest flexural strength (284.03 MPa), open porosity (15.78%), and lowest density (2.37 g cm −3 ). There were chemical reactions occurred between carbon fibers and matrix which formed strong covalent bonds and interfaces. The micrographs also reveal that fiber bridging and pulling-out are the most important reinforcement mechanisms which contribute to the mechanical properties of the composites. [ABSTRACT FROM AUTHOR]

The optimization of the electrodes structure is crucial for supercapacitors. Herein, we report a novel three-dimensional (3D) hierarchical multihole architecture of ternary reduced graphene oxide (rGO)/MnO 2 /carbon foam (CF) nanocomposites. Thereinto, CF not only firstly serves as conductive skeleton but also offers primary pore structure with nickel foam and supporter for electrochemical deposition (ECD) of MnO 2 . Furthermore, rGO covered on electrodes surface both prevents the exfoliation of MnO 2 and integrates with it to construct secondary pore structure. The configuration with three components synergistic effects leads to a high specific capacitance of 356.5 F g −1 at a scan rate of 10 mV s −1 and a long cycle life along with 93.6% specific capacitance retained after 2000 cycles. Also, it even remained 30.6 Wh kg −1 at a large power density of 13.5 kW kg −1 . [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]

High strength lightweight mullite whisker network reinforced ceramic materials was successfully prepared by firing a bauxite - kaolin - coal fly ash mixture with additions of varying mixtures of feldspar - talcum - BaCO 3 - pyrolusite. The mullite whisker network exhibits a unique architecture in which thin mullite crystals layers with anisotropic properties and well controlled crystal size were interweaved with one another. The effects of pyrolusite content on morphologies and properties of resultant ceramic materials were investigated. The phase compositions and microstructures of several samples were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The flexural strength and acid solubility of ceramic materials as functions of sintering temperature were systematically investigated by measuring the flexural strength and acid solubility at different sintering temperature, respectively. The resulting mullite whisker network structure ceramic materials showed optimum performance at sintering temperature around 1390 °C when the content of pyrolusite equals to 6 wt%, such as high strength (190.10 MPa), low density (1.48 g cm −3 ) and low acid solubility (2.55 wt%). The approach opens new opportunities for the sintered ceramic as a proppant material since the ceramic system displays low acid solubility and good flexural strength. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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]

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 I D /I G 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. [ABSTRACT FROM AUTHOR]

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. [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]

Carbon/carbon–silicon carbide (C/C–SiC) composites, as a promising material for brake disks, have been widely concerned by researchers. In this work, the C/C–SiC composite that has potential applications in future advanced braking systems has been fabricated by combining low temperature compression molding (LTCM) and liquid silicon infiltration (LSI). The effects of the carbon fibers (C f ) dispersion and LSI on the properties of the C/C–SiC composite have been investigated. The results demonstrate that the as-prepared composite with a high density of 2.3 g cm −3 and low open porosity of 6% exhibits a high bending strength of 120 MPa and compressive strength of 153 MPa. Moreover, it displays a “False plasticity” phenomenon, indicating the excellent mechanical properties. Additionally, a stable friction coefficient of 0.33 has been also obtained, which demonstrates that the chattering phenomenon can be effectively controlled to obtain comfortable driving conditions during the brake process. [ABSTRACT FROM AUTHOR]

The multi-wall carbon nanotube-reinforced carbon foams were prepared via foaming, carbonization, and graphitization process using pretreatment pitches as matrix precursor and modified multi-wall carbon nanotube as additive. The effects of modified multi-wall carbon nanotube additive amount on the microstructure, mechanical strength, thermal conductivity, and electrical conductivity of carbon foams were investigated by X-ray diffraction, scanning electronic microscopy, universal testing machine, laser thermal conductivity tester, and four-probe resistance meter, respectively. It was found that the introduction of modified multi-wall carbon nanotube had a significant effect on the microstructure of carbon foams. The compressive strength and electrical conductivity of carbon foams increased with the increase of modified multi-wall carbon nanotube additive amount, the maximum were 11.72 MPa and 28.89 × 10 S/m, respectively. However, the thermal conductivity of carbon foams increased firstly with increasing modified multi-wall carbon nanotube additive amount up to 2 wt%, and then decreased. [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]

Carbon foams with high mechanical strength were prepared using coal tar pitches modified with cinnamaldehyde (CMA) and boric acid, via pretreatment, foaming and carbonization process. The properties of modified pitches, pretreatment pitches and resultant carbon foams were studied by Fourier transform infrared spectroscopy (FTIR), optical microscope, thermogravimetry analyzer, X-ray diffractometer (XRD), scanning electron microscope (SEM) and universal testing machine, respectively. Results show that the chemical composition and softening points of pitches are adjusted by modification with different amount of CMA, as well as the morphology and properties of pretreatment pitches. The relation between the properties of modified coal tar pitches and the structure of resultant carbon foams is also investigated. Investigation indicates that the composition and softening point of pitches have a significant impact on the morphology and properties of resultant carbon foams. Moreover, the mechanical strength of carbon foam is also improved via modification of pitches and the highest mechanical strength reaches to 21.27 MPa when the additive amount of CMA is 7 wt%. [ABSTRACT FROM AUTHOR]

The flexible polydimethylsiloxane (PDMS) is emerging as an important platform for future devices, including micro-channels, organic photovoltaic, wearable electronics, and sensors. However, the stability and homogeneousness of functionality on the PDMS surface influence the performance of the devices. The present paper described a method to achieve the chemically stable and uniform functionality of polyethyeleneimine (PEI) on the PDMS surface and the kinetics of gold nanoparticle adsorption on the PEI functionalized PDMS surface was investigated. This study provides potential applications in fabricating PDMS based high performance devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] The variation tendency of secondary QI content is researched. [•] The relation between secondary QI content and the cellular structure is disclosed. [•] It is expected to optimizing the secondary QI content to form appropriate size pores so that to obtain carbon foams with high performance. [ABSTRACT FROM AUTHOR]

Highlights: [•] Carbon nanospheres were synthesized via hydrogen bonding self-assembly. [•] The mass ratio of P123 to ACM was an important influencing factor on the resulting products shape. [•] When the concentration of P123 is high, hollow carbon fibers with very thin shell were always obtained. [•] Partial ordered mesopores structure was maintained within carbon nanospheres used as the EDLC. [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]

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 (<−10 dB or >90%) increased in the frequency range of 8–18 GHz compared to multi-walled carbon nanotube/polyvinyl chloride composites. The reflection loss (<−10 dB) of 0.2 wt% La(NO3)3-doped multi-walled carbon nanotube/polyvinyl chloride composites is the widest from the absorption bandwidth (maximum is 5.12 GHz). [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, coal tar pitch (CTP) was modified with cinnamaldehyde (CMA) in the presence of p-toluene sulfonic acid. The parent CTP and CMA modified CTP were characterized by 1H nuclear magnetic resonance spectroscopy, elemental analysis and scanning electron microscopy. Carbonization behaviors of CMA modified CTPs were studied by thermogravimetric analysis, Fourier transform infrared spectroscopy and X-ray diffraction techniques. The results show that the carbonization behaviors of parent CTP and CMA modified CTPs are much different. The modification of CTP with CMA results in an increase in carbonization yield by 3.46–5.08% when 100g CTP was modified with 5–15ml of CMA. During the carbonization process, methyl and methylene groups of the CMA modified CTP gradually disappear while increasing temperature and its chemical structures change greatly when the temperature is higher than 400°C. In addition, the modification with CMA is beneficial for increasing graphitizability of CTP. [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]

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]

Abstract: Activated carbons with high surface areas were prepared via KOH activation process by microwave (MW) heating. As a comparison, activated carbons were also prepared by conventional heating (EF) method. The influences of KOH/Mesocarbon microbeads (MCMB) weight ratio and activation time on the pore properties of the activated carbons were investigated. For both MW and EF heating methods, the surface area and pore volume increase to a maximum and then decrease with the KOH/MCMB ratio increasing. The effects of activation time on the pore properties depend on the KOH/MCMB ratio. The activated carbons prepared by MW heating have higher surface area and larger pore volume than those by EF heating when KOH/MCMB ratio is the same. The MW heating method shortens the activation time considerably. Activated carbons prepared by MW heating show low content of oxygen containing groups. [Copyright &y& Elsevier]

Abstract: Coal-tar pitch is widely used to prepare composite materials by the several cycles of impregnation and carbonization. Impregnation becomes the control step for cost when the high-density carbon preform is densified. Thus, effects of additives on the permeability of the pitch are investigated by experiments and their mechanisms are discussed according to theoretical analysis of fluid kinetics. Direactive glyceride as well as aluminum sulfate and polyethylene oxides evidently increase permeability by changing the physical structure of pitch. However, divinylbenzene has chemical modification to the pitch in the presence of p-toluene sulfonic acid, which leads to a marked decrease in permeability. In this regard, the former two types of additives are more suitable than the latter one to modify the coal-tar pitch as a precursor to densify the carbon preform with high density. In addition, the permeability drastically depends on the concentrations of additives. [Copyright &y& Elsevier]

Coal-tar pitch is modified with p-methyl benzaldehyde (PMB) in the presence of p-toluene sulfonic acid (PTS). The main characteristics of the modified pitches such as coking value, softening point and solubility are studied in this paper. The molecular structures of the modified pitches are studied using FT-IR and 1H-NMR spectroscopy techniques. In addition, the morphologies of the modified pitches are inspected with SEM, and the optical textures of resultant semi-cokes are characterized by polarized-light microscopy. Results show that the modified pitches have much higher coking value and β-resins content than the parent pitch. There exist many microfibers with a uniform distribution in the modified pitches. Moreover, the modification results in an improvement in the optical textures of resultant semi-cokes. [Copyright &y& Elsevier]

In this paper, coal-tar pitch is modified with divinylbenzene (DVB) in the presence of p-toluene sulfonic (PTS) acid. Carbonization behavior of the modified coal-tar pitch and optical texture of resultant semi-cokes are studied. The carbonization behavior is studied by thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy techniques, respectively. The optical texture of resultant semi-cokes is characterized by reflected polarized light microscopy. The results show that there are marked differences in carbonization behavior of coal-tar pitch and the modified pitches. The modification of coal-tar pitch results in an increase in carbonization yield by 10–18%. The modified pitches have many methyl and methylene functional groups, which gradually disappear and aromatization degree increases with increasing heat treatment temperature. Specially, the modification contributes to a notable improvement in the optical texture of resultant semi-cokes which varies from coarse-grained mosaics to domains. [Copyright &y& Elsevier]

The enhancement of thermally conductive performances for lightweight thermal interface materials is a long-term effort. The superb micro-structures of the thermal conductivity enhancer have an important impact on increasing thermal conductivity and decreasing thermal resistance. Here, globular flower-like reduced graphene oxide (GFRGO) is designed by the self-assembly of reduced graphene oxide (RGO) sheets, under the assistance of a binder via the spray-assisted method for silicone-based spherical alumina (S-Al2O3) composites. When the total filler content is fixed at 84 wt%, silicone-based S-Al2O3 composites with 1 wt% of GFRGO exhibit a much more significant increase in thermal conductivity, reduction in thermal resistance and reinforcement in thermal management capability than that of without graphene. Meanwhile, GFRGO is obviously superior to that of their RGO counterparts. Compared with RGO sheets, GFRGO spheres which are well-distributed between the S-Al2O3 fillers and well-dispersed in the matrix can build three-dimensional and isotropic thermally conductive networks more effectively with S-Al2O3 in the matrix, and this minimizes the thermal boundary resistance among components, owning to its structural characteristics. As with RGO, the introduction of GFRGO is helpful when decreasing the density of silicone-based S-Al2O3 composites. These attractive results suggest that the strategy opens new opportunities for fabricating practical, high-performance and light-weight filler-type thermal interface materials. [ABSTRACT FROM AUTHOR]

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·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. [ABSTRACT FROM AUTHOR]

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]