Scalable Fabrication of an MXene/Cotton/Spandex Yarn for Intelligent Wearable Applications.

Wearable sensors based on MXene have attracted attention, but the large-scale production of MXene-based textile materials is still a huge challenge. Hereby, we report a facile way of incorporating MXene into the traditional yarn manufacturing process by dipping and drying MXene into cotton rovings followed by fabricating an MXene/cotton/spandex yarn (MCSY) using friction spinning. The MXene in the MCSY brings electrical conductivity to the MCSY with well-preserved mechanical properties. Due to its wide sensing range from 408 Pa to 10.2 kPa, the MCSY can be used to monitor human motions in real time, such as writing, walking, and wrist bending. In addition, the MCSY exhibits a stable compression sensing performance even under different strains. Furthermore, the MCSY can be sewn into clothing or onto a mask as an embroidery pattern to develop sensing device prototypes capable of detecting touching or breathing. The reported manufacturing technology of the MCSY will lead to an industrial-scale development of MXene-based e-textiles for wearable applications.

Renewable plant-derived lignin for electrochemical energy systems.

Lignin, as one of the most abundant natural polymers, has been proved to be a promising material for the construction of high-performance electrochemical energy systems, including electrodes, electrolytes, and separators, because of their low-cost and sustainable natures and unique structure with abundant functional group. In this review article, we outline some key contributions in this field such as fundamental principles and various electrochemical energy systems including rechargeable batteries, supercapacitors, solar cells, and fuel cells. At the same time, we also point out the significant scientific discussion and critical barriers for lignin-based materials for electrochemical energy systems and also provides feasible strategies for preparing new sustainable energy materials.

Cellulose-based Ni-decorated graphene magnetic film for electromagnetic interference shielding.

Flexible and ultrathin electromagnetic interference (EMI) shielding films are urgently required to manage increasingly serious radiation pollution. In this work, the EMI shielding performance and flexibility of conductive polymer films were addressed by assembling magnetic graphene-based hybrid and cellulose nanofiber (CNF). Briefly, magnetic graphene hybrid anchored by Ni nanoparticles (TRGO@Ni) was synthesized by in situ thermal reduction. Then, highly flexible and ultrathin CNF/TRGO@Ni film with "brick-mortar" layered structure was assembled via a facile vacuum filtration method. As expected, CNF/TRGO@Ni film with 50 wt% filler loading exhibits an enhanced electrical conductivity (262.7 S/m) and EMI shielding effectiveness (32.2 dB) comparing to CNF/TRGO film. Moreover, the excellent mechanical flexibility of CNF/TRGO@Ni film results in that the electrical conductivity and EMI SE only declines by 7.5% after bending 1000 cycles. The EMI shielding mechanism is attributed to the combination of enhancing impedance mismatch, multireflection in "brick-mortar" lamellar structure and endowing synergetic loss by graphene and Ni nanoparticles.

One-pot mechanochemical exfoliation of graphite and in situ polymerization of aniline for the production of graphene/polyaniline composites for high-performance supercapacitors.

Graphene/polyaniline composites have attracted considerable attention as high-performance supercapacitor electrode materials; however, there are still numerous challenges for their practical applications, such as the complex preparation process, high cost, and disequilibrium between energy density and power density. Herein, we report an efficient method to produce graphene/polyaniline composites via a one-pot ball-milling process, in which aniline molecules act as both the intercalator for the exfoliation of graphite and the monomer for mechanochemical polymerization into polyaniline clusters on the in situ exfoliated graphene sheets. The graphene/polyaniline composite electrode delivered a large specific capacitance of 886 F g-1 at 5 mV s-1 with a high retention of 73.4% at 100 mV s-1. The high capacitance and rate capability of the graphene/polyaniline composite can contribute to the fast electron/ion transfer and dominantly capacitive contribution because of the synergistic effects between the conductive graphene and pseudocapacitive polyaniline. In addition, a high energy density of 40.9 W h kg-1 was achieved by the graphene/polyaniline-based symmetric supercapacitor at a power density of 0.25 kW kg-1, and the supercapacitor also maintained 89.1% of the initial capacitance over 10 000 cycles.

In situ encapsulation of Co3O4 polyhedra in graphene sheets for high-capacitance supercapacitors.

Co3O4 polyhedra were well encapsulated in reduced graphene oxide (rGO) sheets by in situ growth of Co-based zeolitic imidazolate framework (ZIF-67) polyhedra in the presence of graphene oxide followed by thermal annealing. The resultant rGO/Co3O4 composites consist of a continuously-conductive double-network constructed from graphene sheets and the derived N-doped carbons from ZIF-67, showing a large specific surface area of 523 m2 g-1. The as-fabricated symmetrical supercapacitor based on rGO/Co3O4 exhibits a high specific capacitance of 277.5 F g-1 at 25 A g-1 and an energy density of 24.7 W h kg-1 at a power density of up to 40 kW kg-1. The supercapacitor also retains 87.5% of the initial capacitance over 5000 cycles at 5 A g-1. Such large capacitance, high energy density, and excellent cycling stability for rGO/Co3O4 are attributable to the 3D double conductive network from 2D graphene sheets and porous channels of pseudo-capacitive Co3O4 polyhedra.

Homogeneous coating of carbon nanotubes with tailored N-doped carbon layers for improved electrochemical energy storage.

The combination of activity-enriched heteroatoms and highly-conductive networks is a powerful strategy to craft carbon-based electrodes for high-efficiency electrochemical energy storage. Herein, N-doped carbon (N-C) coated carbon nanotubes (N-CNTs) were fabricated via a facile in situ synthesis of polyimide in the presence of carbon nanotubes (CNTs), followed by carbonization. The polyimide-divided N-C layers were uniformly covered on the surface of CNTs with a tailored layer thickness. The as-fabricated N-CNTs were further used as electrode active materials for energy storage. When employed as the electrodes for supercapacitors, the N-CNTs exhibited a specific capacitance of 63 F g-1 at 0.1 A g-1 (an energy density of 1.4 W h kg-1 at a power density of 20 W kg-1), which was much higher than that of pure N-C (5 F g-1) and CNTs (13 F g-1). The supercapacitor also retained 66.7% of its initial capacitance (42 F g-1 at 10 A g-1) after a 100-fold increase in the current density and nearly 100% of its initial capacitance after running 10 000 cycles. Furthermore, functioning as an anode material for a Li-ion battery, the N-CNTs also delivered a larger reversible capacity (432 mA h g-1 at 50 mA g-1), higher rate capability, and better cycling stability compared to pure CNTs. The electrochemical performances of the N-CNTs were improved overall due to the synergistic effects of interconnected 3D networks and core-shell structures capable of facilitating electrolyte percolation and charge transportation, enhancing conductivity and surface/interface wettability, and contributing additional pseudocapacitance.

Superior flame retardancy and smoke suppression of epoxy-based composites with phosphorus/nitrogen co-doped graphene.

Phosphorus and/or nitrogen doping is an effective method of improving the physical and chemical properties of reduced graphene oxide (rGO). In this work, phosphorus and nitrogen co-doped rGO (PN-rGO), synthesized using a scalable hydrothermal and microwave process, was used as an additive to improve the flame retardancy of epoxy resin (EP) for the first time. Chemical structure and morphology characterization confirmed that the nitrogen and phosphorus atoms were doped into the graphite lattice adopting pyrrolic-N, pyridinic-N, quaternary-N and pyrophosphate and metaphosphate forms. Doping increased the oxidization resistance of rGO and the thermal-oxidative stability of its composites' char, while also improving the catalytic charring ability of polymer. Both effects resulted in the formation of a stable char protective layer during burning and to a significant improvement in flame retardation and smoke suppression in the final composites. The peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) for the EP-based composite (containing 5 wt% PN-rGO) decreased by 30.9%, 29.3% and 51.3%, respectively, compared to neat EP. Our work has produced a promising graphene-based flame retardant additive for the mass production of high-performance composites, also expended the application of heteroatom-doped graphene.

Graphene-Enabled Superior and Tunable Photomechanical Actuation in Liquid Crystalline Elastomer Nanocomposites.

Programmable photoactuation enabled by graphene: Graphene sheets aligned in liquid crystalline elastomers are capable of absorbing near-infrared light. They thereafter act as nanoheaters and provide thermally conductive pathways to trigger the nematic-to-isotropic transition of elastomers, leading to macroscopic mechanical deformation of nanocomposites. Large strain, high actuation force, high initial sensitivity, fast reversible response, and long cyclability are concurrently achieved in nanocomposites.

Incorporation of liquid-like multiwalled carbon nanotubes into an epoxy matrix by solvent-free processing.

Covalent attachment of 2,2'-(ethylenedioxy)-diethylamine to multiwalled carbon nanotubes (MWCNTs) produced amino-functionalized MWCNTs which behaved like liquids at ambient temperature. These liquid-like MWCNTs (l-MWCNTs) could be homogeneously dispersed and chemically embedded in an epoxy matrix by solvent-free processing. In contrast, solid MWCNTs (s-MWCNTs) functionalized by 1,8-diaminooctane were poorly dispersed in epoxy although they possess chemical structures and functionalization comparable to l-MWCNTs. An epoxy composite filled with pristine MWCNTs (p-MWCNTs) was also fabricated in the absence of a solvent at the same loading for comparison. The molecular level coupling of l-MWCNTs and epoxy provided significant improvements in overall mechanical properties relative to those composites containing p-MWCNTs and s-MWCNTs. The Young's modulus, storage modulus, tensile strength, failure strain and toughness of neat epoxy were increased by 28.4, 23.8, 22.9, 24.1 and 66.1%, respectively, by adding 0.5 wt% of l-MWCNTs. Thus, functionalized carbon nanotubes in liquid form contributed to better dispersion and superior interfacial bonding with the epoxy matrix, thereby facilitating greater mechanical reinforcement efficiency.