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The main contribution of semiconductor nanomaterials to surface-enhanced Raman scattering (SERS) comes from charge transfer (CT) between the absorbing molecules and the semiconductor. However, it is still challenging to realize the combined effects of the electromagnetic mechanism (EM) and the chemical mechanism (CM) for semiconductor-based SERS substrates. Herein, we demonstrate and design double-shelled ZnO (ZnO-DS) hollow microspheres by a modified hydrothermal/solvothermal process. SERS experiments and theoretical simulations proved that the excellent SERS activity is mainly attributed to the combined effect of Mie resonances generated by the nanocavities in the unique hollow double-shell nanoparticles and the CT effect excited by special structure ZnO. Particularly, the produced ZnO-DS SERS substrates exhibited a low limit of detection (LOD, 1 × 10–7 M for 4-MPY), outstanding sensitivity (EF = 1.2 × 104), and high stability (RSD = 10.4%, over 30 days of storage at room temperature). Furthermore, benefiting from the matching of energy levels of the ZnO-DS substrate and probe molecules, the sulfhydryl molecules with similar structures could be selectively distinguished in complex environments. We visualize that this work will resolve the current dilemma between sensitivity and selective detection of SERS substrates and expect to enable the monitoring of target molecules in the environment containing complex mixtures such as food safety and environmental protection. [ABSTRACT FROM AUTHOR]

The rational and effective combination of multicomponent materials and ingenious microstructure design for efficient electromagnetic wave (EMW) absorption are still challenging. In this paper, MXene was used as the aerogel matrix, modified with sea urchin-like magnetic Co/N-doped carbon@polyaniline (Co-NC@PANI), gelatin was introduced as the reinforcement phase of the aerogel backbone, and a microwave absorber with high efficiency and excellent performance was successfully prepared. The sea urchin-like Co-NC@PANI not only adjusted the impedance matching of the MXene but also introduced a magnetic loss mode into the composite. The multicomponent interfacial polarization, heterostructure, three-dimensional (3D) lightweight porous structure, and electromagnetic synergy strategy enabled the MXene-based aerogel modified by Co-NC@PANI (MCoP) to exhibit surprising EMW absorption properties. The maximum reflection loss (RLmax) of the aerogel composite reached -62.4 dB, and the effective absorption bandwidth (EAB) reached 6.56 GHz when the loading was only 12%. In addition, through electromagnetic simulation experiments, the change in the electromagnetic field before and after EMW passed through the materials and the distribution of the volume loss density of EMW by the coaxial ring were observed. The coordinated electromagnetic balance strategy in the 3D network provides inspiration for the construction of materials and expands the research direction of lightweight and outstanding microwave absorbers. [ABSTRACT FROM AUTHOR]

Taking all-day, all-weather airport security protection as the application demand, and aiming at the lack of complex meteorological conditions processing capability of current remote sensing image aircraft target detection algorithms, this paper takes the YOLOX algorithm as the basis, reduces model parameters by using depth separable convolution, improves feature extraction speed and detection efficiency, and at the same time, introduces different cavity convolution in its backbone network to increase the perceptual field and improve the model's detection accuracy. Compared with the mainstream target detection algorithms, the proposed YOLOX-DD algorithm has the highest detection accuracy under complex meteorological conditions such as nighttime and dust, and can efficiently and reliably detect the aircraft in other complex meteorological conditions including fog, rain, and snow, with good anti-interference performance. [ABSTRACT FROM AUTHOR]

In this work, epoxy resin (EP)-based aqueous polyurethane (PU) anionic PU dispersion was synthesized by the prepolymer and self-emulsification method. The PU prepolymer was first synthesized to serve as seeds. Then, trimethylolpropane and A-type EP (E-51) were introduced into it, followed by neutralization and emulsification reactions, and, finally, it formed a crosslinking network structural waterborne PU emulsion. The effect of epoxy contents on the particle size, rheological properties, storage stability, thermal stability, mechanical properties, and hydrophilicity of the resulting PU films was systematically investigated. The results showed that the PU dispersions displayed excellent storage stability and crosslinking density, and the glass transition temperature of the composite films was increased. The properties of self-made epoxy-modified polyurethane emulsion and polyester-cotton fabric before and after finishing were tested. The wrinkle resistance, hydrophobicity, and strength of the finished polyester/cotton fabric are improved, and it exhibits better color fastness to washing and rubbing. [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]

Based on the large specific surface area and excellent adsorption potential of graphene quantum dots (GQDs) and zeolitic imidazolate framework-8 (ZIF-8) materials, a GQDs@ZIF-8 composite was constructed to achieve optimal matching of the microstructure and to acquire efficient adsorption of volatile organic compounds (VOCs). GQDs and ZIF-8 were synthesized and then compounded by the solution co-deposition method to obtain GQDs@ZIF-8 composites. GQDs were uniformly decorated on the surface of the ZIF-8 metal-organic framework (MOF), effectively restraining the agglomeration, improving the thermal stability of ZIF-8 and forming abundant active sites. Thus, the VOC removal percentage and adsorption capacity of the GQDs@ZIF-8 composites were significantly improved. Toluene and ethyl acetate were chosen as simulated VOC pollutants to test the adsorption performance of the composites. The results showed that, after the addition of GQDs, the adsorption property of GQDs@ZIF-8 composites for toluene and ethyl acetate was obviously improved, with maximum adsorption capacities of 552.31 mg/g and 1408.59 mg/g, respectively, and maximum removal percentages of 80.25% and 93.78%, respectively, revealing extremely high adsorption performance. Compared with raw ZIF-8, the maximum adsorption capacities of the composites for toluene and ethyl acetate were increased by 53.82 mg/g and 104.56 mg/g, respectively. The kinetics and isotherm study revealed that the adsorption processes were in accordance with the pseudo-first-order kinetic model and the Freundlich isotherm model. The thermodynamic results indicated that the adsorption process of the GQDs@ZIF-8 composites was a spontaneous, endothermic and entropy increase process. This study provides a new way to explore MOF-based adsorption materials with high adsorption capacity which have broad application prospects in VOC removal fields. [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]

Plasmonic resonance from 2D anisotropic metallic nanoparticles for surface-enhanced Raman scattering (SERS) has attracted substantial attention for applications in chemical and environmental monitoring because of its intrinsic electromagnetic "hotspot" and orientation-dependent optical properties. Nevertheless, their sensing applications have been limited by their poor stability toward oxidation and moisture and complicated fabrication processes for large-scale assembly, especially on flexible substrates. In this work, we demonstrate water-stable nanofibers as active SERS substrates electrospun from anisotropic gold nanoprisms (AuNPs) mixed with poly-(vinyl alcohol) (PVA) at a concentration of 2.5–20 nM, followed by cross-linking by glutaraldehyde (GA) vapor at room temperature. Using 4-mercaptobenzoic acid (4-MBA) as the target molecule, we show that the nanofiber mat with 20 nM AuNPs exhibits high sensitivity at a concentration as low as 10–10 M 4-MBA with an enhancement factor of 107 and good uniformity over a very large area (20 cm2) with an average relative standard deviation of <0.074. The cross-linked PVA/AuNP nanofibers are stable against water without an obvious decrease in the SERS signal. In the detection of Rhodamine 6G (R6G) molecules in the water solution, the Raman intensity of R6G shows almost no decay over 3 months compared to that of the as-prepared mat. Further, we show the detection of trace pesticide (10–6 M) on the orange exocarp, suggesting that our fiber mat could be applied for potential applications including food safety, biomedicine, and environmental monitoring. [ABSTRACT FROM AUTHOR]

Despite the significant progress made in polymer/graphene nanocomposites, the development of high-performance polymer/graphene nanocomposites, combined with excellent mechanical and electromagnetic shielding properties, remains a priority and a challenge. The lanthanum doping large-size graphene oxide (La-LsG) was obtained via static oxidation and thermal treatment. The effects of static oxidation and lanthanum doping on the property and morphologies of graphene and composites were investigated. The physicochemical property of considerable graphene oxide (GO), large-size graphene oxide (LsGO), lanthanum-doped graphene oxide (La-GO), La-LsG was analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, and X-ray energy spectroscopy (EDS). SEM and EDS characterized the microstructure of the composite material, and the mechanical properties and electromagnetic shielding performance of the composite material were studied. La-GO and La-LsG exhibited good dispersion and structural integrity, as well as enhancing the strength of the composites. The La-LsG/poly (methyl methacrylate) (PMMA) composites exhibited excellent mechanical properties (is ca. 73.6 MPa) and electromagnetic shielding effectiveness (is ca. 28 dB) in X-band frequencies (8.2–12.4 GHz), which may be assumed to be a promising integrated material of structure and function. [ABSTRACT FROM AUTHOR]

Three types (type-A, B, and C) of composite polymeric membranes (CPMs) based on poly vinyl chloride (PVC) and different fillers (sodium polyacrylate and sodium polyacrylate-graphite) soaked in water and 0.5 N HCl were prepared using solvent casting method. Different physicochemical parameters such as microscopic surface study, water uptake, perpendicular swelling, density, porosity (ε), ion exchange capacity, and conductivity of the as the prepared CPMs were evaluated. Interestingly, type-A CPM cast with filler-A has greater values of the above parameters except density and ionic conductivity than those of type-B and C CPMs. The water uptake of type-A, B and C composite membranes was respectively in the range of 220.42–534.70, 59.64–41.65, and 15.94–2.62%. Ion exchange capacity of type-A, B and C CPMs was in the range of 3.669 × 107–2.156 × 107, 5.948 × 107–1.258 × 107, and 1.454 × 107–1.201 × 107 m.eq.g−1 respectively while the conductivity order was type-A < B < C. These types of CPMs may be helpful in many applications including proton exchange membranes, fuel cell like devices, as sensors for different metals, gas purification, water treatment, and battery separators. [ABSTRACT FROM AUTHOR]

As an old member of excellent conductive materials, graphene was selected as one of the materials for the preparation process of this research. Magnetic ferrites have always been one of the candidates for absorbing materials due to their excellent magnetic loss. Based on the rGO/CoFe2O4 (Cr) composite material prepared by the one-step hydrothermal method, three groups of rGO/CoFe2O4/Ag (CAr) with different Ag+ content were prepared by controlling the addition amount of Ag+. And the final prepared rGO/CoFe2O4/Ag-1 (CAr-1) exhibited extremely excellent electromagnetic wave absorption performance. The effective reflection loss under the optimal thickness can be obtained by adjusting the thickness. When its thickness is 2.1 mm, the best reflection loss at 13.1 GHz is − 56.5 dB, and the maximum effective absorption bandwidth (EAB) is 4.0 GHz (11.1–15.1 GHz). It provides a feasible solution for the development and research of electromagnetic absorption materials. Under the synergistic effect of ferrite magnetic particles with excellent magnetic effect, Ag particles with dielectric loss and graphene, the electromagnetic wave absorption of the material is well improved. [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]

With the development of electronic communication technology, the issues of electromagnetic (EM) wave pollution have become increasingly prominent, and the requirements for EM wave absorbing materials are rising. Polypyrrole (PPy), an important type of conductive polymers, has attracted increasing attention in the applications of EM wave absorbing due to their facile synthesis process, low density, good conductivity, corrosion resistance, and stable chemical properties. Various PPy-based composite materials exhibit excellent electromagnetic absorbing properties and have been widely reported in the literature. In this review, the recent development and understanding of PPy and PPy-based composites materials in the applications of EM wave absorption are summarized in detail. In particular, as a conductive loss-type absorbing material, we focus on the design and fabrication of PPy-based composites and explore the significant impact of EM parameters on the EM wave absorbing properties. Finally, perspectives are provided for future directions of advanced PPy and PPy-based composites for microwave absorbers. [ABSTRACT FROM AUTHOR]

In order to better meet the energy demand of rapidly developing electronic devices, it is urgent to develop electrode materials with high capacity and stability. In this article, we report a polyhedral carbon framework, which can evolve from a solid to hollow structure through rational design. Thanks to a good hollow, porous and thin shell structure, the material can be used for lithium–sulfur batteries (LSBs) and lithium/sodium ion batteries. For the lithium/sodium storage process, the capacity can be stabilized at 333.3 mA h g−1 (1000)/150.4 mA h g−1 (2000), even at a high current density of 10.0 A g−1. In addition, this unique material can also be used to modify commercial PP separators, which provides huge benefits to LSBs. The synergistic adsorption of polysulfides is achieved through physical/chemical interactions. It can provide a 625.4 mA h g−1 reversible capacity after 1000 cycles at a current density of 1.0C, and the capacity decay rate is as low as 0.046%. At the same time, this excellent cycle stability can be maintained under extremely high sulfur loading conditions. The sharing of this work emphasizes the importance of rational design of nanostructures for improving the cycle performance of secondary batteries. [ABSTRACT FROM AUTHOR]

High-performance absorbers with laminated and three-dimensional structures for abundant interfaces can improve electromagnetic wave absorption property obviously. Meanwhile, the combination and dispersion of components have a positive effect on the microwave absorption (MA) property for excellent absorption bandwidth. Herein, accordion-like MXene/Co-ZIF and MXene/Ni-ZIF composites were synthesized by electrostatic self-assembly between MXene and metal–organic frameworks (Co-MOF and Ni-MOF) and then pyrolyzed in the H2/Ar mixed atmosphere (Co-MOF and Ni-MOF named as Co-ZIF and Ni-ZIF, respectively, after pyrolysis). The MXene/Co-CZIF 50% composites displayed good absorption performance with the optimal RL value of −60.09 dB at 7.36 GHz and the broadened absorption bandwidth 9.3 GHz (RL < −10 dB). MXene/Ni-CZIF 50% exhibited promising performance with the RL value measured up to −64.11 dB at 5.12 GHz, and possessed the ultrabroad effective response bandwidth of 4.56 GHz (RL < −10 dB). Furthermore, a unique accordion-like structure, magnetic–dielectric synergistic, multiple interface scatterings and reflections, and dipole polarization were said to improve MA properties. This study provided a method for the synthesis of absorbers with tunable electromagnetic properties and wide absorption bandwidth of MXene-based composites. [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]

Cinnamaldehyde- (CMA-) modified coal tar pitches (CTPs) are prepared in the presence of acids. In this paper, the effect of boric acid and p-toluene sulfonic acid on the pyrolysis and graphitization process of CMA-modified CTP was studied. The pyrolysis process was studied by Fourier transform infrared spectroscopy, thermogravimetric analysis and derivative thermogravimetry, and polarized-light microscopy. In addition, the graphitization process was studied by X-ray diffraction and Raman spectroscopy. The results indicate the carbon yield of CMA-modified CTP with boric acid as catalyst (B7C10) is higher than that of CMA-modified CTP with p-toluene sulfonic acid as a catalyst (P7C10). In addition, under the same experimental condition (heated at 400°C and held for 1 h), the mesophase spheres of B7C10 are more regular than those of P7C10 and the largest diameter of the mesophase spheres can reach to 40 um. Further, after the graphitization process, the graphitization degree of B7C10 is higher than that of P7C10. So, it is more effective to modify CTP with boric acid as a catalyst. [ABSTRACT FROM AUTHOR]

In this work, a series of ammonium–lauric salts (ALS) was prepared with lauric acid and amines as small molecular shale swelling inhibitor. The inhibitors were screened by the linear expansion test first, and the result shows that the inhibitor prepared by lauric acid and diethylenetriamine with the mole ratio of 2:1 (ALS-2) displays excellent inhibition effect on the hydration expansion of bentonite. The inhibition of ALS-2 to bentonite was fully evaluated by various methods in the following work, including clay linear swelling test and particle distribution measurement. The results show that ALS-2 has superior performance to inhibit the hydration swelling and dispersion of bentonite, and the swelling rate of bentonite in 0.5% ALS-2 was reduced to 29.7%. In water-based drilling fluid, ALS-2 is compatible with the conventional additives, and it can improve the lubricity of the mud cake obviously after aged under 120°C. Besides, it can control the particle size of bentonite in water. The inhibition mechanism of the ammonium–lauric salts was discussed in detail through physical adsorption, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared spectroscopy. [ABSTRACT FROM AUTHOR]

Porous copper (Cu) films were facilely and greenly fabricated by low-current electrical field-induced assembly of ~ 3 nm Cu nanoparticles (NPs) in several minutes using generated hydrogen bubbles as dynamic negative templates. The porous films had open three-dimensionally (3D) interconnected nanopores and uniform pore size distribution and exhibited a hierarchical structure composed of supraparticles that were further composed of the Cu NPs. Lattice-to-lattice connectivity in the self-assembly of the NPs in the 3D structures enables fast charge transport. The structure/morphology of the porous Cu materials can be tuned by adjusting the concentration of the additives, applied potential/current densities and assembly time. A growth mechanism of the porous films was reasonably proposed for the field-induced assembly of the Cu NPs. The porous Cu film-supported Si electrode showed high capacity of 1173 mAh g−1 and retention rate of 87% after 10 cycles at 1 C. Our research sheds a light on preparing 3D nanoporous structures especially for suitable electrodes in electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

Interfacial perimeter sites between metal and support are often important for catalysis. A mononuclear titanium siloxy complex III, Ti(acac)2[OSiC6H5N(OCH3)2]2 was synthesized to generate TiOx units of different degrees of clustering to decorate Au nanoparticles. Two different methods of preparation were examined; one was to deposit III onto Au/SiO2 and the other was to form III-covered Au nanoparticle first before deposition onto SiO2. The former method generated more highly dispersed TiOx units, while larger domains of TiO2 were formed with the latter method, as deduced by UV-vis and XAS characterization. A model was proposed to explain how TiOx dispersity could be related to the preparative procedures. These samples were further tested as catalysts in selective oxidation of propane in a stream of O2 and H2. They exhibited different product selectivities. The sample with more dispersed TiOx units were more selective for acetone formation versus propene formation. The results confirmed the important role of both the Au-TiOx interface at the perimeter and the extent of Ti isolation in the TiOx phase in the reaction. [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]

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]

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

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

Rapidly evolving fields of biomedical, energy, and (opto)electronic devices bring forward the need for deformable conductors with constantly rising benchmarks for mechanical properties and electronic conductivity. The search for conductors with improved strength and strain have inspired the multiple studies of nanocomposites and amorphous metals. However, finding conductors that defy the boundaries of classical materials and exhibit simultaneously high strength, toughness, and fast charge transport while enabling their scalable production, remains a difficult materials engineering challenge. Here, composites made from aramid nanofibers (ANFs) and gold nanoparticles (Au NPs) that offer a new toolset for engineering high strength flexible conductors are described. ANFs are derived from Kevlar macrofibers and retain their strong mechanical properties and temperature resilience. Au NPs are infiltrated into a porous, free-standing aramid matrix, becoming aligned on ANFs, which reduces the charge percolation threshold and facilitates charge transport. Further thermal annealing at 300 °C results in the Au-ANF composites with an electrical conductivity of 1.25 × 104 S cm−1 combined with a tensile strength of 96 MPa, a Young's modulus of 5.29 GPa, and a toughness of 1.3 MJ m−3. These parameters exceed those of most of the composite materials, and are comparable to those of amorphous metals but have no volume limitations. The plasmonic optical frequencies characteristic for constituent NPs are present in the composites with ANFs enabling plasmon-based optoelectronic 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]

Polymer matrices with excellent mechanical properties, thermal stability and other features are highly demanded for the effective utilization within nanocomposites. Here, we fabricate free-standing aramid nanofiber films via spin coating of an aramid nanofiber/dimethyl sulfoxide solution. Compared with traditional film fabrication methods, this process is time-saving and also able to easily tune the thickness of the films. The resultant films show greatly improved stretchability than that of Kevlar threads and relatively high mechanical strength. Typically, these films with a thickness of 5.5 µm show an ultimate strength of 182 MPa with an ultimate tensile strain of 10.5%. We also apply a finite element modeling to simulate the strain and strength distributions of the films under uniaxial tension, and the results of the simulation are in accordance with the experimental data. Furthermore, the aramid nanofiber films exhibit outstanding thermostability (decomposition at ~ 550 °C under N atmosphere and ~ 500 °C in air) and chemical inertness, which would endure acid and alkali. The simple method demonstrated here provides an important way to prepare high-performance aramid nanofiber films for designing new composite systems. [ABSTRACT FROM AUTHOR]

Because of its special porous structure and novel physical and mechanical properties, porous copper is widely studied in many fields, especially in high-performance lithium-ion batteries. It is quite necessary for researchers to understand the recent progress of porous copper. Herein, we review the preparations, properties, and lithium-ion battery (LIB) applications of porous copper. Its main research direction and development trend are also pointed. [ABSTRACT FROM PUBLISHER]

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]

Carbon foam/silica aerogel composite as a promising thermal insulation material was prepared under ambient pressure successfully in the present work. Carbon foam was prepared by pretreatment, foaming, and carbonization process, while silica aerogel was synthesized by sol-gel method. The microstructure, morphology characteristics, compression strength, and thermal properties of composite were characterized by infrared spectroscopy, x-ray diffraction, scanning electron microscope, universal testing machine, and laser flash thermal detector, respectively. Results showed that silica aerogel was successfully synthesized in the surface foam cells of carbon foam due to the closed cell structure of carbon foam. Moreover, the compressive strength of the carbon foam was not affected by the silica aerogel in the cell structure of carbon foam, while its thermal insulation property at room temperature was improved. [ABSTRACT FROM AUTHOR]

Current collectors are essential features of batteries and many other electronic devices being responsible for efficient charge transport to active electrode materials. Three-dimensional (3D), high surface area current collectors considerably improve the performance of cathodes and anodes in batteries, but their technological implementation is impeded by the complexity of their preparation, which needs to be simple, fast, and energy efficient. Here we demonstrate that field-stimulated assembly of ∼3 nm copper nanoparticles (NPs) enables the preparation of porous Cu NP films. The use of NP dispersions enables 30× reduction of the deposition current for making functional 3D coatings. In addition to high surface area, lattice-to-lattice connectivity in the self-assembly of NPs in 3D structures enables fast charge transport. The mesoscale dimensions of out-of-plane features and the spacing between them in Cu films made by field-stimulated self-assembly of NPs provides promising morphology for current collection in lithium ion batteries (LIBs). Half-cell electrochemical models based on self-assembled films show improved specific capacity, total capacity, and cycling performance compared to traditional flat and other 3D current collectors. While integration of active electrode material into the 3D topography of the current collector needs to be improved, this study indicates that self-assembled NP films represent a viable manufacturing approach for 3D electrodes. [ABSTRACT FROM AUTHOR]

Using La(NO)-doped multiwalled carbon nanotubes (MWCNTs-La(NO)) as the absorber and polyvinyl chloride (PVC) as the matrix, the electromagnetic and absorbing properties of MWCNT-La(NO)/PVC composites were studied. The complex permittivity of MWCNT-La(NO)/PVC composites decreased slightly with increasing frequency. The reflection loss minimum declined with increasing thickness and shifted to lower frequency region in the frequency region of 2-18 GHz, and the microwave absorbing property increased, compared to MWCNT/PVC composite. The reflection loss minimum (−32.57 dB, 3.52 GHz) of MWCNT-La(NO)/PVC composite with 8 mm thickness was the lowest. It is feasible to develop microwave absorbing composites with strong absorption and wide band properties utilizing rare earth-modified MWCNTs as the absorber. [ABSTRACT FROM AUTHOR]

Amine-functionalized siloxane oligomers were synthesized and used successfully to prepare colloidal Au particles smaller than 1 nm. Using NMR to follow the interaction of Au(THT)Cl with the functionalized siloxane, it was determined that the amine ligands displaced the THT ligand effectively. By comparison with other functionalized siloxane oligomers/compound, parameters such as density of ligating groups, oligomer steric barrier and reduction rates were found to be essential for the formation and stability of subnanometer Au particles. Without further treatment, the formed Au particles were active catalysts for the reduction of p-nitrobenzaldehyde by triethylsilane, forming an imine as the major coupling product. Deposition of the Au colloids onto silica, followed by thermal treatment to remove the organic groups resulted in subnanometer Au on silica, indicating this to be a promising method of fabricating subnanometer supported Au catalyst. [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]

The governing parameters controlling the glass transition temperature of polymer-grafted particle systems are analyzed for the particular case of polystyrene (PS)-grafted silica colloids in the dense grafting limit. At a given degree of polymerization of surface-grafted chains the glass transition temperature is found to increase as compared to linear chain polymers of equivalent degree of polymerization. The difference in the glass transition temperature between polymer-grafted particle systems and their respective linear polymer analogs increases with decreasing degree of polymerization of surface-grafted chains and levels off at similar plateau values for particle brushes of distinct particle core size. The trend toward increased glass transition temperature is interpreted as a consequence of the increased steric hindrance in polymer-grafted particles that counteracts the relaxation of surface-grafted polymer chains. The increase in glass transition temperature is shown to be approximately consistent with the chain conformational regimes that are predicted on the basis of a Daoud-Cotton type scaling model. [ABSTRACT FROM AUTHOR]

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]