Graphene is highly desirable as an electromagnetic wave absorber because of its high dielectric loss and low density. Nevertheless, pure graphene is found to be non-magnetic and contributes to microwave energy absorption mostly because of its dielectric loss, and the electromagnetic parameters of pure graphene, which are out of balance, result in a bad impedance matching characteristic. In this paper, we report a facile solvothermal route to synthesize laminated magnetic graphene. The results show that there have been significant changes in the electromagnetic properties of magnetic graphene when compared with pure graphene. Especially the dielectric Cole-Cole semicircle suggests that there are Debye relaxation processes in the laminated magnetic graphene, which prove beneficial to enhance the dielectric loss. We also proposed an electromagnetic complementary theory to explain how laminated magnetic graphene, with the combined advantages of graphene and magnetic particles, helps to improve the standard of impedance matching for electromagnetic wave absorbing materials. Besides, microwave absorption properties indicate that the reflection loss of the as-prepared composite is below À10 dB (90% absorption) at 10.4-13.2 GHz with a coating layer thickness of 2.0 mm. This further confirms that the nanoscale surface modification of magnetic particles on graphene makes graphenebased composites have a certain research value in electromagnetic wave absorption.

An N-superdoped 3D graphene network structure with an N-doping level up to 15.8 at% for high-performance supercapacitor is designed and synthesized, in which the graphene foam with high conductivity acts as skeleton and nested with N-superdoped reduced graphene oxide arogels. This material shows a highly conductive interconnected 3D porous structure (3.33 S cm ), large surface area (583 m g ), low internal resistance (0.4 Ω), good wettability, and a great number of active sites. Because of the multiple synergistic effects of these features, the supercapacitors based on this material show a remarkably excellent electrochemical behavior with a high specific capacitance (of up to 380, 332, and 245 F g in alkaline, acidic, and neutral electrolytes measured in three-electrode configuration, respectively, 297 F g in alkaline electrolytes measured in two-electrode configuration), good rate capability, excellent cycling stability (93.5% retention after 4600 cycles), and low internal resistance (0.4 Ω), resulting in high power density with proper high energy density.

In order to achieve wearable displays, fiber-shaped supercapacitors have been widely explored. [5,6] Compared with the conventional planar structure, they could be woven into electronic clothes by the well-developed textile technology to achieve ventilating function. [7][8][9][10] Generally, in order to fabricate fiber-type device, a line-shaped electrode is necessary. There have been many kinds of alternative fiberlike electrode. For instance, electrochemically active materials are coated on fibrous structural supports (such as polymer fibers [11,12] and metal wires) [13] to fabricate the fiber-shaped electrode. However, the poor conductivity or the high cost of these supports restricts their further development. As an alternative approach, carbon materials (carbon nanotubes (CNTs), [14] graphene, [15] activated carbon) [16] have been made into fibers for potential wearable applications. Unfortunately, a constraint of these carbonaceous materials lies in their low capacitance, and these fibers are not mechanically tough to be weaved and knitted by machines. More recently, MXenes, a new 2D materials family of early transition metal carbides and carbonitrides, have shown much promise over other supercapacitor electrode materials. [17] The most widely studied MXene to date has been Ti 3 C 2 T x . It was obtained by selectively etching off the Al element from the host of layered carbide Ti 3 AlC 2 . [18] The surfaces of the etched resultant are typically terminated by O, OH, and/or F with a formula Ti 3 C 2 T x , where T x stands for a general surface termination. [19] In general, the rich chemistry and tunable surface termination, metallic conductivity, and surface hydrophilicity of MXenes make them attractive candidates for energy-storage applications, especially for supercapacitor electrode materials. Recent results have shown that Ti 3 C 2 T x electrodes have high capacitance and perform well at high rates, such as Ti 3 C 2 T x freestanding films, [17] self-assembled Ti 3 C 2 T x films with nickel foam, [20] sandwich-like MXene/CNT papers, [21] and so on. [22,23] Very recently, a wire-type supercapacitor based on Ti 2 CT x MXene in a basic electrolyte was demonstrated. [24] Its very low capacitance and energy density, and the rigid stainless steel wire support, make the fabricated supercapacitor not ideal for wearable purpose. Thus, exploring a strategy to fabricate fibertype MXene-based supercapacitors with high capacitance is very urgent, attractive, and challenging.Herein, we propose a solution-processed methodology to fabricate all-solid-state, flexible, and fiber-based supercapacitors employing Ti 3 C 2 T x MXene. We choose silver-plated nylon fibers

No abstract