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Achieving multifunctionality to broaden the application scenarios is the development direction of electromagnetic wave (EMW) absorbing materials in the future. Here, a waterproof magnetic carbon foam (CF) was successfully prepared using a simple high-temperature pyrolysis and dip coating process, where the magnetic Fe 3 O 4 nanoparticles were homogeneously and tightly encapsulated on the carbon skeleton of CF with the help of low surface energy PDMS, achieving the expected high-efficient EMW absorption performance. Except the 3D porous structure that contributes stronger EMW absorption through multi-reflection and scattering, the coexistence of conductive carbon skeleton and magnetic Fe 3 O 4 can supply the dielectric-magnetic dual-loss, which is also beneficial for better impedance matching. In addition, the amounts of heterointerfaces and abundant crystalline defects and doped N atoms in graphitic carbon can also generate additional polarization loss. Furthermore, high-efficient EMW absorption capacity was achieved by tuning the pyrolysis temperature, of which the CF pyrolyzed at a temperature of 900 °C (PDMS/Fe 3 O 4 /CF-900) exhibited a minimum reflection loss (RL min) value of −47.36 dB with 3.15 mm thickness and a maximum effective absorption bandwidth (EAB max) up to 9.76 GHz with 4.2 mm thickness. What's more, combining with the merits of high conductivity, hydrophobicity, and special 3D porous structure, the expected multifunctionality was also successfully achieved for the prepared PDMS/Fe 3 O 4 /CF-900, where it displays the excellent thermal management performance including a high Joule heating temperature of 161 °C at only 5 V and reliable heating capacity over 1500 s, high-efficient oil-water separation capacity such as high absorption amount (45.58 times), rapid absorption (1.14 s), and stable cyclic adsorption-desorption performances, and great thermal insulation property with a temperature difference up to 219.9 °C that make it to be promising infrared stealth material. This work provides a feasible strategy for the rational design and application of novel lightweight multifunctional high-performance EMW absorbing materials. [Display omitted] • Magnetic carbon foam was prepared for multifunctional EMW absorbing material. • The foam displays a RL min of −47.36 dB and wide EAB of 9.76 GHz. • The foam possesses great potential in the field of personal thermal management. • The foam can be applied for infrared stealth of military equipment. [ABSTRACT FROM AUTHOR]

Being as lightweight and thin as possible is highly desirable for electromagnetic interference (EMI) shielding materials in electronic devices as the high requirement in miniaturization and weight reduction. Constructing three-dimensional (3D) porous conductive architecture into two-dimensional (2D) film provides one of the feasible strategies. Herein, pyrolytic carbon aerogel films from aramid nanofiber (ANF) with novel skin-core structure containing compact film skin and 3D porous nanofiber network core were fabricated by a facile method. The abundant conjugate aromatic structure in backbone endows ANF-derived carbon aerogel film with a high conductivity of 1029.5 S/m. Remarkably, the high electrical conductivity, as well as the 3D porous skin-core structure, which not only constructs the interconnected electron transmission paths but also significantly extends the propagation path of EM waves, enables the carbon aerogel film a high EMI shielding effectiveness (SE) of 41.4 dB at low density (54.4 mg/cm3) and thin thickness (162 μm) with high specific shielding effectiveness (SSE/t) of up to 47122.6 dB cm2/g. Besides, ANF-derived carbon aerogel film exhibits an excellent photothermal conversion ability, which greatly broadens the application environment. More interestingly, the easy and flexible preparation method with adjustable film thickness, density and area makes large-scale production of carbon aerogel film possible. [Display omitted] • ANF-derived carbon aerogel film prepared by a facile and scalable method. • The film reveals skin-core structure with compact skin and nanofiber network core. • The carbon aerogel film exhibits high EMI SE at low density and thin thickness. • The carbon aerogel film shows an excellent photothermal conversion capacity. [ABSTRACT FROM AUTHOR]

The chemical conversion of the surface termination of 2D transition metal carbides/nitrides (MXenes) has opened up a design space that previously had not been extensively explored for this functional material. Herein, via a simple sealed thermal method, the amino terminated groups were successfully introduced on Ti 3 C 2 MXene surface. The substitution reaction of amino group to hydroxyl group was proposed to elucidate this aminated process. As the amination would reduce the carrier density on the surface of MXene, the electrical conductivity of MXene-NH 2 film decreased, while it still reached a high conductivity of 2.11 × 104 S m−1. This film also possessed an excellent electromagnetic interference shielding effectiveness of 16160 dB cm2 g−1. Importantly, although the introduction of amino termination altered Zeta potential value, Zeta potential sign remained negative and the MXene-NH 2 exhibited excellent dispersity in water similar to that of traditional MXenes. Furthermore, the existence of covalent bonds endowed MXene-NH 2 polymer composite film with improved mechanical properties. Compared with that of traditional CMC/MXene film, the tensile strength and fracture energy of CMC/MXene-NH 2 increased by 65.5% and 132.7%, respectively. These results demonstrated that the introduction of amino terminated group on MXene surface would be an effective strategy to obtain higher performance MXene-based films. [Display omitted] [ABSTRACT FROM AUTHOR]

For smart devices, there is a growing demand for multi-functional soft actuators, nevertheless, well-developed actuators always respond to single stimulus, and it is still challenging to achieve the application diversity standards. Herein, a bidirectional multi-stimuli responsive soft actuator based on Ti 3 C 2 T X MXene-cellulose nanowhiskers (CNWs)-polyvinyl alcohol (PVA)/polydimethylsiloxane (PDMS) multilayer membranes is proposed (MXCP-P). By grafting CNWs onto MXene nanosheets, a freestanding composite film with gradient layered structure was prepared. Due to the hygroscopicity among MXene nanosheets, increased interlayer space is in favor of adsorption/desorption of water molecules, causing invertible shape change and humidity-driven deformation with a rapid response. Based on high photothermal conversion capacity of MXene and large difference of coefficient of thermal expansion between PDMS and MXene, the MXCP-P achieves an ultra-large amplitude and fast response driven by natural light. A Venus flytrap soft robot is constructed with good actuation behaviors. The MXCP-P film was employed as actuators in the opera of The Male Phoenix Pursui from Han Dynasty and in shadow puppetry "Monkey King Subdus the White-Bone Demon" of China, both exhibiting excellent performances towards humidity and light stimuli synchronously. This paper inspires a new strategy for multi-stimuli responsive soft bionic robots and intelligent traditional shadow play. MXCP-P based multi-stimuli responsive flexible actuator was fabricated, showing improved mechanical properties and bidirectional bending characteristics. In addition to its application in traditional fly traps and rolling robots, the MXCP-P actuator is also employed to develop traditional Chinese opera culture, such as "The Male Phoenix Pursui" and "Shadow puppetry". [Display omitted] [ABSTRACT FROM AUTHOR]

Graphene (Gr) and its derivatives (such as graphene oxide (GO), reduced graphene oxide (RGO), nanoparticles decorated graphene, etc.) reinforced metal matrix composites (MMC) with good structural mechanical properties and functional properties have wide applications in aerospace, automotive, electronics and military fields. However, some problems exist in preparing high performance MMC including poor wettability between Gr-type fillers and metal matrix, and weak interfacial bonding strength. Efficient methods for preparing Gr-related nanomaterials filling metal matrix parts with high performance, especially for complex parts still need be further developed. The engineering application field of Gr MMC needs to be further expanded. In this paper, methods to prepare high performance MMC including surface modification of Gr and its derivatives, properties and applications of these reinforced MMC were reviewed with detailed examples. The main challenges were analyzed and the development trend of Gr-type types reinforced MMC was discussed. Image 1 • Surface modification of graphene improved wettability between graphene and metal matrix. • Methods for preparing metal matrix composites were reviewed. • Properties of graphene reinforced metal matrix composites were reviewed. • Applications of the metal based graphene composites were reviewed. [ABSTRACT FROM AUTHOR]

Excess sludge, a carbon-rich valuable by-product from wastewater treatment, is utilized as a carbon precursor for synthesizing porous activated carbon. However, improving specific surface area (S BET) is the main challenge for the sludge derived activated carbon (SAC). In this study, the carbonization process was optimized as following: carbonization temperature of 900 °C, heating rate of 10 °C/min, and dwell time of 30 min. Moreover, the residue heavy metals and bound water remaining in the sludge were demonstrated to be important in the pore formation of the SAC. The metals acted as hard template to form the pores in the SAC after the metals were removed by acid wash. The bound water was found to be soft templates for forming pores due to its evaporation during carbonization. A maximum S BET of 1018.8 m2/g was achieved for the SAC when the bound water content was controlled at 2 wt%. Image 1 [ABSTRACT FROM AUTHOR]

In this work, a unique high negative permittivity is observed in the carbon nanosphere (CNS) supported nanosilver-polydopamine (PDA) metacomposites (called CNS-PDA/Ag). The CNS possesses a uniform spherical structure (average diameter of about 200 nm) with a bridge to link CNS together. The Ag nanoparticles are observed to be uniformly deposited on the surface of CNS-PDA core-shell structures with an average diameter of around 10–20 nm. Both impedance and optical band gap results confirm that the CNS-PDA/Ag metacomposites can form a conductive network pathway for further improving their electrical conductivity (about 1 and 2 magnitudes higher than that of CNS and CNS-PDA, respectively). With the support of CNS, the enhanced high negative permittivity observed in the CNS-PDA/Ag metacomposites (about −6.1 × 105) compared with CNS (around −1.2 × 105), CNS-PDA (around 2.5 × 104), and PDA/Ag (around 2.0) is ascribed to uniform decoration of PDA and Ag nanoparticles, induced electric dipole polarization, excellent electrical conductivity as well as anisotropy in dielectric and electrical properties of CNS, PDA, and Ag. The negative permittivity and positive reactance demonstrate an inductance character of the CNS-PDA/Ag metacomposites. This work opens up a new strategy for design and development of metacomposites. Image 1 [ABSTRACT FROM AUTHOR]

The use of reduced graphene oxide (rGO) in high-temperature oxidization (HTO) environment, is limited by its poor thermal oxidation and fire resistance. In this study phosphorus and nitrogen co-doped reduced graphene oxide (PN-rGO) with high oxidation and fire resistance was prepared by hydrothermal and microwave treatment and its thermal oxidation decomposition kinetics and mechanisms were analyzed. Concisely, PN-rGO presents an increment of 162 °C in the decomposition temperature relative to undoped rGO (WrGO), and excellent fire resistance with only a ∼20% mass loss after burning. Thermal oxidation degradation kinetics reveals that WrGO shows continuously increasing activation energy (E) within a range of 119.7–182.9 kJ/mol, while PN-rGO exhibits almost constant E of ∼171.8 kJ/mol during main degradation stage. Moreover, the improved E at initial stage by phosphorus/nitrogen doping, combining with the char analysis, suggested that the introduction of strong chemical bonds replacing the reactive oxygen-containing groups was the key to preventing the oxidation of rGO. As one of the main properties, the electrical conductivity of PN-rGO is well kept after HTO treatment. This work demonstrates that a doping strategy can effectively expand the application of graphene-based devices in HTO environment. Image 1 [ABSTRACT FROM AUTHOR]

Abstract The search of multifunctional epoxy nanocomposites with both strength and toughness combined with smart features such as electrical conductivity is essential in design of advanced materials. In this work, by utilizing a binary nanofiller strategy, both strength and toughness as well as high electrical conductivity are obtained in epoxy with trace nanopolystyrene grafted with epichlorohydrin (nano g -PS) to facilitate the dispersion of multi-walled carbon nanotubes (MWCNTs). The increased tensile strength (37.6%) and flexural strength (34.4%) are acquired in nano g -PS (0.0677 vol%)/MWCNTs (0.0335 vol%)/epoxy in contrast to pure epoxy. A remarkably improved tensile toughness up to 379.2% and an increased elongation at break up to 208.3% are obtained in this epoxy nanohybrid. The synergistic interactions among nano g -PS, MWCNTs and epoxy matrix as well as the state transition of nano g -PS from glassy state to fluid state provide an improved dispersion of nanofillers which is responsible for the increased electrical conductivity and enhanced mechanical properties. The decreased surface resistivity allows these nanohybrids to sufficiently dissipate surface charges as an antistatic material. This work provides an effective way to disperse carbon nanotubes with small amount of thermoplastic PS to simultaneously strengthen and toughen the thermosetting epoxy while introducing highly conductive function. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract Based on the contributions of carbon nanostructures and their composited species, great advances in electromagnetic wave interference shielding have been achieved. In this article, recent progress in electromagnetic wave shielding enabled by the synergism of carbon nanostructures and their corresponding composites is discussed encompassing the factors of microstructural defects, filler concentration, filler alignment, filler inherent conductivity and the surrounding temperature. Carbon nanostructures and their composites would energize the advanced electromagnetic wave shielding because of their light weight, high corrosion resistance, excellent thermal, mechanical, and electrical properties, broad absorption frequency bandwidth and cost-effectiveness. In this context of identifying suitable carbon composites that can enhance electromagnetic wave absorption. This review provides updated electromagnetic wave shielding knowledge of carbon nanostructures and their composites as well as their prospects and challenges. Graphical abstract Image [ABSTRACT FROM AUTHOR]

Abstract Macroscopic three-dimensional (3D) free-standing porous all-graphene aerogel with ultralight density and high compressibility is successfully fabricated through a mild in-situ self-assembly and thermal annealing processes. The formed interconnected 3D porous graphene network, high thermal stable all-graphene composition and large porosity of aerogels made it possible to remove heat quickly during combustion, exhibiting a conspicuous fire-retardancy. Meanwhile, excellent recoverable compressibility with high strain levels of up to 75% endowed the aerogel with high sensitive strain-responsive characteristic in volume electrical conductivity, thereby opening a new way for realizing the adjustment of internal free space and electrical conductivity of 3D architecture. Based on the results, the microwave absorption performance of the graphene aerogel was effectively self-adjusted via a simple mechanical compression. The optimal absorbing value was up to 61.09 dB with a broad qualified bandwidth of 6.30 GHz at the thickness of 4.81 mm when the compression strain ratio of the sample was controlled to be 30%. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

In this work, a novel flexible electrically resistive-type strain sensor with special three-dimensional conductive network was developed based on reduced graphene oxide (RGO)-decorated flexible thermoplastic polyurethane (TPU) electrospun fibrous mats. Scanning electron microscopy results indicated that RGO was localized on surfaces of the TPU fibers uniformly and formed conductive paths. The interaction between electrospun TPU fibers and RGO was investigated by using Fourier transform infrared spectra and X-ray diffraction. These fibers conductive paths connected with each other and constructed an excellent three-dimensional conductive network. The special hierarchical conductive network endowed our RGO/TPU strain sensors with a desirable integration of good stretchability and high sensitivity (gage factor (GF) of 11 in strain of 10% and 79 in strain of 100% in reversible strain regime), good durability and stability (stretch/release test of 6000 cycles) and a fast response speed. The mechanism of the evolution of residual resistance and residual strain of RGO/TPU strain sensors under cyclic loading were investigated in detail. RGO/TPU strain sensors were attached on skin or clothes to monitor various human motions. The results demonstrate that our flexible strain sensors have wide application prospects in smart wearable device. [ABSTRACT FROM AUTHOR]