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In the present study, the unique three-dimensional graphene coated nickel (Ni/C) foam reinforced silicon carbide (Ni/C@SiC) composites were first obtained via the precursor impregnation and pyrolysis (PIP) processes. The microstructure images indicated that the SiC fillers were successfully prepared in the skeleton pores of the Ni/C foam. The influence of the PIP cycles on the microwave absorption performances was researched, and the results indicated that after the primary PIP process, Ni/C@SiC–I possessed the optimal microwave absorbing performance with a minimum reflection loss(RL) of −25.87 dB at 5.28 GHz and 5.00 mm. Besides, the RL values could be below −10.00 dB from 5.88 GHz to 7.74 GHz when the corresponding matching thickness was 3.85 mm. However, the microwave absorption properties of Ni/C@SiC-II and Ni/C@SiC-III were tremendously degraded as the PIP times increased. At last, the electromagnetic parameter, dielectric loss, attenuation constant as well as impedance matching coefficient were further investigated to analyze the absorbing mechanism, which opened a new path for the certain scientific evaluation of the absorbing materials and had extremely important to the defence technology.

Improved compressive strength and preeminent microwave absorbing properties are of great importance to meet the harsh requirements of the thermal environment. Herein, the SiC network reinforced SiO2 aerogel composites were synthesized via the carbonation, chemical vapor deposition, and sol-gel process using melamine sponge as the precursor and carbon foam as the structural template, followed by a heat treatment in the elevated temperature range of 300–1200 °C. The results showed that the compressive performance was significantly enhanced as a superior compressive response of 3.46 MPa at 9.49 % strain was obtained owning to the strengthened SiC skeleton wrapped by the SiO2 aerogel with the rising temperature. Besides, the composite after being warmed at 900 °C was provided with an efficient electromagnetic absorption capacity with a minimum reflection loss value of −55.38 dB at 16.56 GHz and a maximum effective frequency bandwidth of 8.16 GHz at 4.10 mm, resulting from the optimal attenuation constant as well as superior impedance matching ratio. Given the outstanding compressive strength and microwave absorbing characteristics, the aerogel composite has a good prospect in the complex electromagnetic fields.

Deep subwavelength highly confined and long-range optical propagation is vital for photonics integration. However, the performance of the guided mode could be improved by the trade-off between light confinement and loss. Here, we demonstrate a high-performance hybrid waveguide consisting of a high-index nanowire separated from a linear array by a low-index dielectric gap. The array significantly achieves the plasmonic platform optimization based on a linear combination of few-layer graphene (FLG) and hexagonal boron nitride (hBN) layers. Through the hybridization of graphene plasmon polaritons and hyperbolic phonon polaritons mode, the resulting hybrid waveguide shows at least double times larger propagation distance and smaller mode area than the multilayer waveguide. Further, modulated by altering material configuration and geometric effects, the mode properties reveal that it is more flexible to adjust the optical transmission, along with a strong deep-subwavelength mode with low loss. Because of highly confined low-loss propagation, the hybrid waveguide is expected to be an excellent building block for various mid-infrared photonic integrated circuits. The present structure also has the potential to be extended to other FLGs, like magic-angle twisted bilayer graphene and trilayer graphene/hBN moiré superlattice.

Sodium-ion batteries (SIBs) are regarded as promising low-cost alternatives to the prevailing lithium-ion batteries. However, most anode materials for SIBs suffer from low initial coulombic efficiency (ICE), limiting their commercial applications. Herein, we demonstrate a Na-ion anode with an extremely high ICE of 99.4%, based on cobalt sulfide (Co9S8/CoS) nanoflakes grown on graphite foam (GF) in a diglyme-based electrolyte. The achievement of such a high ICE can be ascribed to the following three aspects: (i) negligible side reactions between a diglyme-based electrolyte and Co9S8/CoS, owing to a much higher Fermi level of diglyme reduction than anode potential μA of Co9S8/CoS, which can block electron transfer from the anode to the electrolyte, (ii) highly reversible conversion reaction of Co9S8/CoS, and (iii) much lower initial capacity loss of substrate GF, compared with other sorts of carbon. The underlying rules revealed in this study serve as general guidelines in the development of sodium-ion anodes to achieve superb ICE. Ministry of Education (MOE) Accepted version The authors gratefully acknowledge the Ministry of Education (MOE) of Singapore for the funding of this research through the following grants, AcRF Tier 1 (Reference No: RG103/16); AcRF Tier 1 (RG195/17); AcRF Tier 3 (MOE2016-T3-1-006 (S)).

The microstructure is a key factor for the comprehensive performance of carbon foam, especially for mechanical property. SiC nanowires/melamine-based carbon foam composites with a designed controllable double-nest microstructure were fabricated, which was made of a kind of hairy structure consisting of carbon skeleton with SiC nanowires sprouting out from them. This composite was ultralight with a minimum density of 5.56 mg/cm3. It also exhibited a good mechanical property that the compressive strength was improved to 45.67–73.11 kPa for each different microstructure, which is over 3–4.8 times than that of the matrix. This straining process of this designed double-nest microstructure was further investigated, and three mechanical models were built based on the octahedral model for analyzing the compressive process of this composite. By calculating and simulating the proposed model C, we obtained an empirical equation, and it was successfully utilized to calculate the compressive stress of this double-nest microstructure.

Three-dimensional (3D) aerogels have attracted more and more attention in oil–water separation, due to their advantages of low density, high porosity, and large specific surface area. However, their application is greatly limited due to their hydrophilic and low adsorption properties. In this work, we report a 3D MoS2–polyvinylpyrrolidone (PVP) aerogel, prepared by a freeze-drying method, where PVP was used as a skeleton to support the aerogel. As a surfactant, PVP can easily attach to the surface of MoS2 nanosheets and facilitate the interconnection between nanosheets. The 3D MoS2–PVP aerogel exhibits low density, high porosity, good hydrophobicity, and excellent adsorption capacity (195–649 times). Moreover, after 30 cycles, the structure of the 3D MoS2–PVP aerogel is well kept and the adsorption capacity is still retained, at 93.5% and 92.9%, by squeezing and distillation, respectively. Therefore, the obtained 3D MoS2–PVP aerogel is a promising adsorption material and has great practical application potential in oil–water separation.

Porous three-dimensional SiC/melamine-derived carbon foam (3D-SiC/MDCF) composite with an original open pore structure was fabricated by the heat treatment of the commercial melamine foam (MF), carbonization of the stable MF, and chemical vapor deposition of the ultra-thin SiC coating. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to detect the microstructure and morphology of the as-prepared composites. The results indicated that the 3D-SiC/MDCF composites with the coating structure were prepared successfully. The obtained minimum reflection loss was -29.50 dB when the frequency and absorption thickness were 11.36 GHz and 1.75 mm, respectively. Further, a novel strategy was put forward to state that the best microwave absorption property with a thin thickness of 1.65 mm was gained, where the minimum reflection loss was -24.51 dB and the frequency bandwidth was 3.08 GHz. The excellent electromagnetic wave absorption ability resulted from the specific cladding structure, which could change the raw dielectric property to acquire excellent impedance matching. This present work had a certain extend reference meaning for the potential applications of the lightweight wave absorption materials with target functionalities.

The porous structure has been proved to be beneficial to improve the microwave absorption performance. In this article, the SiC coating reinforced carbon foam (SiC/C) was synthesized via the direct...

A novel structure-controllable reticulated silicon carbide (SiC) skeleton-reinforced silica aerogel composites (SiC/aerogel) were fabricated successfully by template method. Three-dimensional SiC skeletons prepared by different deposition time were prepared via the chemical vapor deposition technology, and then the silica aerogel was induced by the sol–gel process. The test results showed that the mechanical properties increased and thermal conductivities decreased remarkably after impregnating reticulated SiC skeleton with silica aerogel. The SiC/aerogel-24 possessed the highest compressive strength of 0.82 MPa with the thermal conductivity of 0.1597 W/(m·K) at 600℃, while the SiC/aerogel-12 exhibited the lowest thermal conductivity of 0.1244 W/(m·K) and its compressive strength was 0.64 MPa. The present work reported a novel method to manufacture the structure-controllable reticulated SiC aerogel composite which could be used as a high-temperature super-thermal insulation material for the potential applications.

The ultrathin SiC coating/melamine-derived porous carbon foam composite (SiC/PCF) was synthesized for the first time by the stable treatment of the commercial melamine foam (MF), carbonization stage of the steady MF, and chemical vapor deposition of the SiC thin films. The microstructure analysis demonstrated that the SiC/PCF composites with layered structures and altered dielectric response were fabricated eventually. The minimum reflection loss of −25.93 dB was obtained when the thickness was 1.05 mm and the measured frequency was 17.20 GHz. Meanwhile, the reflection loss could drop below −10 dB in the whole thickness with the frequency ranging from 3.00 to 18.00 GHz, which showed a more excellent microwave absorbing performance compared with PCF. Furthermore, the influencing mechanism of both the impedance matching ratio and attenuation constant was discussed to provide actual guidances in designing excellent microwave absorbing materials for functional applications.

A novel hybrid foam composite consisting of the three-dimensional (3D) interconnected carbon foam (CF) and ultrathin silicon carbide (SiC) coating was prepared via the carbonization, chemical vapor infiltration, and chemical vapor deposition process. By means of incorporating the pyro carbon and SiC coating on the surface of the CF skeleton, not only the thermostability and compression resistance but also the electromagnetic absorption performances of the as-prepared composites were enhanced. The results were that the novel hybrid foam was thermostable, as beyond 87% weight remained in the air atmosphere at 700 °C, and the strong compression strength explored the potential application in the critical environments. As expected, the foam possessed an excellent electromagnetic absorption property with the minimum reflection loss of −37.189 dB at 13.92 GHz at 2.0 mm. It indicated that the SiC coating with bridged junctions, twinning interfaces, and abundant stacking faults took great effect on the improvement...

SiC coating had key effects on designing and optimizing electromagnetic wave absorption properties of SiC films reinforced foam composites. In this paper, ultrathin three-dimensional reticulated SiC/porous carbon foam composite (3D-SiC/PCF) was prepared eventually, followed by the successive stable treatment, carbonization stage and chemical vapor deposition process. The results showed that the complex permittivities of 3D-SiC/PCF-II were much lower than that of PCF and 3D-SiC/PCF-I. Although the attenuation constant decreased with the induction of SiC coating, the impedance matching ratio increased. Besides, 3D-SiC/PCF-II possessed a better wave absorption performance, where the minimum reflection loss was −29.74 dB. At last, the influencing mechanism of both the impedance matching ratio and the attenuation constant behind was discussed to further probe the effect of the SiC content and provide suggestions for functional applications.

Commonly, carbon foam derived from commercially available melamine foam showed brittle characteristics. In this paper, the carbon foam was prepared via the direct carbonization of the melamine foam, and chemical vapor deposition was employed to deposit ultra-thin SiC films on the CF skeleton. The evolution, microstructure, mechanical strength, and thermal properties of the as-prepared SiC/CF composites were investigated. Test results showed that a novel SiC skeleton with a three-dimensional interconnected network was prepared successfully. The thickness of the SiC filmes had a significant influence on the compression and thermal properties of the composites. The SiC/CF-II possessed a higher compression performance than that of SiC/CF-I, while the thermal insulation was relatively much poorer. This present work had some reference meaning to the correlation studies of the thermal insulation material for the potential applications while bearing live loads.

A double network nested foam composite with tunable electromagnetic wave absorption performance was fabricated via a carbonization, impregnation, and chemical vapor infiltration method. The research results indicated that the three-dimensional interconnected carbon foam was successfully enhanced by the SiC nanowire network. As expected, the electromagnetic absorption performance of the as-prepared SiC nanowire reinforced carbon foam (SiCnw/CF) was greatly improved by the introduction of the SiC nanowires. The SiCnw/CF composite prepared with a lower concentration of Ni catalyst possessed an excellent microwave absorption property with the lowest reflection loss value of −36.31 dB with a matched thickness of 2.60 mm accompanied by the widest effective bandwidth of 4.52 dB. An increase in catalyst concentration degraded the electromagnetic absorption ability to a certain extent. A potential microwave absorption schematic diagram was finally proposed, and it stated that the SiC nanowire network played an essential role in the improvement of the electromagnetic absorption properties.

Novel three-dimensional SiC/melamine-derived carbon foam composite filled by silica aerogel (SiC/MDCF–Aerogel) was first fabricated by the pyrolysis process of commercial melamine foam, chemical vapor deposition of ultrathin SiC films, and the sol–gel method of silica aerogel. The results indicated that the SiC/MDCF–Aerogel composite consisted of the SiC three-dimensional open-celled network structure and the pregnant silica aerogel in the pores. Tiny cracks on the interface of skeletons and clumps were induced during the aging process, which was drastically beneficial to the microwave-absorbing properties. A minimum reflection loss could be obtained as low as −18.41 dB at the measured frequency of 16.92 GHz when the thickness of the absorber was 3.65 mm, and the reflection loss could drop below −10 dB when the selected frequencies ranged from 15.80 to 17.52 GHz, along with the thickness ranging from 2.75 to 5.0 mm, which possessed a relatively better microwave absorption performance especially at a highe...

Herein, a supermolecular-scale cage-confinement pyrolysis strategy is proposed to build two dielectric electromagnetic wave absorbents, in which MoO

Hard carbons are the most promising commercialized anodes for sodium-ion batteries (SIBs). However, it is still a great challenge to design highly stable hard carbon anodes coupled with a large reversible capacity. Herein, a self-supported hollow interconnected carbon foam (HICF) is developed by one-step pyrolysis of a commercial and low-cost melamine sponge. The integration of interconnected network and hollow feature can not only provide strong mechanical stability and additional inner space to effectively accommodate the structural deformation from Na+ insertion/extraction, but also enable fast electron and Na-ion transport to achieve a large reversible capacity. As a result, HICF delivers a large reversible capacity of 306 mAh g−1 at 100 mA g−1 and an ultralong cycle life with 86.4% capacity retention over 1000 cycles at 1000 mA g−1. The superior Na-storage performance is also contributed by the maximized content (63.24%) of pseudo-graphitic phase in HICF realized by tuning pyrolysis time, as the pseudo-graphitic phase could store more sodium ions and maintain more stable microstructure owing to its appropriate D-spacing than highly disordered phase. Furthermore, kinetic analysis based on cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) verifies the adsorption–intercalation mechanism. This work provides a low-cost and high-performance anode candidate for the future practical applications of SIBs. Ministry of Education (MOE) Z.F.C acknowledges the financial support from the Equipment Advanced Research Field Foundation of China (No. 61409220210 and No. 61409220204). X.L.Y acknowledges the financial support from the Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX19_0178) and the program of China Scholarships Council (No. 201906830022). Z.X.S. acknowledges the financial support from Ministry of Education, Singapore, AcRF Tier 1 (Reference No. RG103/16 and RG195/17) and AcRF Tier 3 (MOE2016-T3-1-006 (S)).

Silica aerogels were synthesized by using tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as co-precursors via the sol–gel method under the microwave irradiation condition. The optimal molar ratio of MTES:TEOS: EtOH: H2O is 0.8:1:8:4, and the obtained aerogels showed the bulk density is 0.097 g/cm3, the surface area is 760.56 m2/g, and pore diameter is 6.06 nm, respectively. The microstructure on the skeleton of the bone networks was investigated by TEM, and the FTIR confirmed that the OH groups were substituted by the CH3 groups prepared by MTES/TEOS co-precursor, the superhydrophobic property was described with a water contact angle up to 168.0°.

Herein, a supermolecular-scale cage-confinement pyrolysis strategy is proposed to build two dielectric electromagnetic wave absorbents, in which MoO2 nanoparticles are sandwiched uniformly between porous carbon shells and reduced graphene oxide (RGO). Both sandwich structures are derived from hybrid hydrogels doped by two different crosslinkers (with/without oxygen bridge), which can precisely confine Mo source (e.g., PMo12 ). Without adding magnetic components, both absorbents exhibit excellent low frequency absorption performance in combination with electrically tunable ability and enhanced reflection loss value, which is superior over other relative 2D dielectric absorbers and satisfies the requirements of portable electronics. Notably, introducing oxygen bridges in the crosslinker generates a more stable confining configuration, which in turn renders its corresponding derivative exhibiting an extra multifrequency electromagnetic wave absorption trait. The intrinsic electromagnetic wave adjustment mechanism of the ternary hybrid absorbent is also explored. The result reveals that the elevated electromagnetic wave absorbing property is attributed to moderate attenuation constant and glorious impendence matching. The cage-confinement pyrolysis route to fabricate 2D MoO2 -based dielectric electromagnetic wave absorbents opens a new path for the design of electromagnetic wave absorbents used in multi/low frequency.

For high-efficiency microwave absorber, it is wise to integrate the porous structure and SiC material. In this work, the hollow SiC foam with a double interconnected network is proposed via a simple chemical vapor deposition and direct oxidation process. The SiC film imparts the foam with excellent mechanical property and microwave absorption performance. As a result, the fabricated SiC foam possesses a superior compressive response of 1.409 MPa at 17.51% strain, which is much higher than the original C foam or SiC reinforced C foam. Besides, SiC foam shows a minimum reflection loss value of −50.75 dB at 4.85 mm at 6.00 GHz. The effective bandwidth frequency and electromagnetic absorption efficiency also prove the superiority of the hollow porous architecture at the specified thickness, followed by a simple interpretation of the microwave absorbing mechanism. Given the excellent characteristics, the SiC foam has the enormous applied potential as a lightweight absorber in complex microwave absorbing conditions, especially for high temperature applications.

Three-dimensional carbon foam reinforced by the chemical vapour deposition (CVD) SiC coating possessed an enhanced microwave absorbing performance. The effect of the CVD SiC on the properties of the carbon foam was researched. As a result, the microwave absorbing performance improved with the thicker SiC coating as the minimum reflection loss value decreased from −20.67 to −33.65 dB while the bandwidth frequency increased from 5.04 to 5.94 GHz, which was ascribed to the stronger basis dielectric response networks and interface polarization. In addition, the internal relation between the impedance matching value and attenuation coefficient was illustrated to further dig the absorbing mechanism, followed by a simple schematic diagram. Given the excellent performance of the basic material and exceptional structure characteristics, it has the prospect of becoming a superior functional composite in absorbing applications.

The silica aerogel composite reinforced by reticulated SiC skeleton (SiC/CF-Aerogel) was manufactured successfully via the chemical vapor deposition of the SiC coating and sol-gel process of silica aerogel in this paper. The results indicated that the SiC coating was deposited on the carbon skeleton with the induction of silica aerogel in the pores. The mechanical properties were enhanced due to the 3-dimensional reinforcement, which possessed a higher compressive response compared with the pure silica aerogel. Besides, SiC/CF-Aerogel possesses fine adiabatic performance with a thermal conductivity of 0.161 W m−1 K−1 at 700 °C. A physical heat model was proposed to illustrate the heat transfer to better understand the excellent thermal properties. It had a big practical potential for future applications.

The fabrication of the three-dimensional (3D) porous framework normally required the assistance of carbon foam. In this paper, the ultralight flexible melamine foam-derived carbon foam (MDCF) was obtained by the direct carbonization process. The influence of the pyrolysis temperature on the microstructure, compressive strength, and thermal conductivity properties of the as-prepared MDCF samples was studied systematically. The results showed that MDCF inherited the 3D open-hole architecture of the starting melamine foam despite the carbon skeleton. The MDCF obtained at 900 °C possessed the highest compressive stress of 19.0 kPa at 10% strain and the lowest effective thermal conductivity of 0.0262 W·m−1 K−1 at normal temperature. To further probe the internal connection, the relationships of the compressive stress and the porosity, as well as the thermal conductivity and the average pore size were investigated. It demonstrated that the pyrolysis temperature had evident effects on the final performances.

In this article, reduced graphene oxide/glass composite fiber was prepared from mixing graphene oxide and glass powder by ultrasonic dispersion, planetary grinding, high-temperature sintering, and melting wire drawing. The effects of reduced graphene oxide content on the mechanical and electrical properties of the fiber were investigated. Thermal gravimetric analyzer, differential scanning calorimeter, x-ray diffraction, and energy-dispersive x-ray spectroscopy analysis revealed that the graphene oxide was reduced to reduced graphene oxide in the sintering process and the performances of the composite fiber were improved. The tensile strength of reduced graphene oxide/glass composite fiber was 20% higher than the pristine glass fibers by the addition of 0.5 wt% of reduced graphene oxide. Reduced graphene oxide content was positively correlated with composites conductivity, and according to the percolation theory, the percolation threshold of reduced graphene oxide/glass composite fiber was about 0.5 wt%, and the conductivity of the composite fibers was increased by four orders of magnitude compared to the pristine glass fibers when the content of reduced graphene oxide was 0.5 wt%.

Ceramic wool felt, as an excellent insulating material, was usually used in industrial, automotive, aerospace and medical engineering to keep temperature which depended mostly on the production phases. In this paper, the ceramic wool was produced by the melt-spinning process and separated by the two-layer process to get the finer diameter and better insulation. The microstructures and properties of the ceramic wool were examined. The results indicated that the mean diameter of the ceramic wool was 2.75 μm in the upper layer, while it was 3.93 μm in the lower layer. The slag ball content in ceramic wool was 0.9878% in the upper layer and 4.1404% in the lower layer. The thermal conductivity of the upper ceramic wool at room temperature and 500 °C was 0.031 W m−1 K and 0.105 W m−1 K, respectively. The thermal conductivity of the lower ceramic wool at room temperature and 500 °C was 0.035 W m−1 K and 0.130 W m−1 K, respectively. It proved that the two-layer process was efficient to separate the ceramic wool and slag ball.