Query: MXene  supercacitor

title: Ultra light MXene aerogel/wood derived porous carbon composites with wall like "mortar/brick" structures for electromagnetic interference shielding
abstract: Renewable porous biochar and 2D MXene have attracted significant attention in high end electromagnetic interference (EMI) shielding fields, due to unique orderly structures and excellent electrical conductivity (s) value. In this work, the wood derived porous carbon (WPC) skeleton from natural wood was performed as a template. And excellent conductive and ultra light 3D MXene aerogel was then constructed to prepare the MXene aerogel/WPC composites, based on highly ordered honeycomb cells inner WPC as a microreactor. Higher carbonization temperature is more conducive to the graphitization degree of natural wood. MXene aerogel/WPC composites achieve the optimal EMI SE value of up to 71.3 dB at density as low as 0.197 g/cm3. Such wall like "mortar brick" structures (WPC skeleton as "mortar" and MXene aerogel as "brick" not only effectively solve the unstable structure problem of MXene aerogel networks, but also greatly prolong the transmission paths of the electromagnetic waves and dissipate the incident electromagnetic waves in the form of heat and electric energy, thereby exhibiting the superior EMI shielding performance. In addition, MXene aerogel/WPC composites also exhibit good anisotropic compressive strength, excellent thermal insulation and flame retardant properties. Such ultra light, green and efficient multi functional bio carbon based composites have great application potential in the high end EMI shielding fields of aerospace and national defence industry, etc.

title: Flame retardant poly(vinyl alcohol)/MXene multilayered films with outstanding electromagnetic interference shielding and thermal conductive performances
abstract: With the miniaturized and high frequency development in electronic products, polymeric films synchronously with high electromagnetic interference (EMI) shielding effectiveness (SE) and thermal conductivity (TC) are urgently needed. In this work, poly (vinyl alcohol)/transition metal carbide (PVA/MXene) films featured with alternating multilayered structure were fabricated through multilayered casting. The continuous MXene layer provided a compact network for conducting heat and electron, endowing the multilayered film with excellent EMI SE and TC synchronously. In particular, the 27 mm thick PVA/MXene multilayered film (containing 19.5 wt% MXene in total) exhibited an electrical conductivity of 716 S/m, a maximum EMI SE of 44.4 dB and a specific EMI SE (SSEt) of 9343 dB cm2 g 1. Meanwhile, the multilayered film showed a high in plane TC of 4.57 W/mK, enhanced by almost 23 fold compared with that of neat PVA. Moreover, the multilayered architecture endowed the film with remarkable anti dripping performance. This work provides a novel and feasible strategy for fabricating flame retardant polymeric thermal conductive and EMI shielding films, which will have enormous prospect in advanced electrical devices.

title: Honeycomb structural rGO MXene/epoxy nanocomposites for superior electromagnetic interference shielding performance
abstract: Honeycomb structural rGO (rGH) was constructed by taking Al2O3 honeycomb as template, and MXene was then self assembled on the rGH via electrostatic adsorption, to obtain honeycomb structural rGO MXene (rGMH) Afterwards, the rGMH/epoxy nanocomposites with outstanding electromagnetic interference (EMI) shielding performance were successfully prepared by addition of epoxy resin. The introduction of 3D rGMH can fully play synergistic effects of rGO and MXene, to greatly improve the electrical conductivity (s) and EMI shielding effectiveness (EMI SE) values of rGMH/epoxy nanocomposites. With the same loading of MXene, the s and EMI SE values of rGMH/epoxy nanocomposites decrease with the increase of honeycomb cell size. Significantly enhanced s (387.1 S/m) and EMI SE (55 dB) values are achieved when applying the cell size of 0.5 mm with 1.2 wt% rGO 3.3 wt% MXene loading, which are respectively 2978 and 5 times of rGM/epoxy nanocomposites (s of 0.13 S/m, EMI SE of 11 dB) at the same loading of directly blending rGO MXene fillers.

title: In situ fabrication of 1D CdS nanorod/2D Ti3C2 MXene nanosheet Schottky heterojunction toward enhanced photocatalytic hydrogen evolution
abstract: Benefiting from excellent metallic conductivity, full spectrum solar energy absorption and rich active sites on the surface, atomically thin two dimensional transition metal carbide (2D MXene) shows great promise in improving solar to hydrogen efficiency and has drawn intense interest in the field of photocatalysis. However, controllable construction of ultrathin 2D MXene based heterojunction photocatalysts still remains a significant challenge. Herein, one dimensional (1D) CdS nanorod/2D MXene nanosheet heterojunctions with well defined nanostructures and strong interfacial coupling are fabricated by in situ assembling solvothermally generated CdS nanorods on ultrathin Ti3C2 MXene nanosheets. Due to their specific interface characteristics, 1D/2D Schottky heterojunction is capable of providing accelerated charge separation and a lower Schottky barrier for solar driven hydrogen evolution from water splitting. As expected, the Schottky based photocatalyst is 7 fold more active in the illuminated hydrogen evolution reaction (HER) than pristine CdS nanorods, implying the synergistic effects between n type semiconductor CdS and highly conductive 2D Ti3C2 MXene nanosheets.

title: Scalable Manufacturing of Free Standing, Strong Ti3 C2 Tx MXene Films with Outstanding Conductivity.
abstract: Free standing films that display high strength and high electrical conductivity are critical for flexible electronics, such as electromagnetic interference (EMI) shielding coatings and current collectors for batteries and supercapacitors. 2D Ti3 C2 Tx flakes are ideal candidates for making conductive films due to their high strength and metallic conductivity. It is, however, challenging to transfer those outstanding properties of single MXene flakes to macroscale films as a result of the small flake size and relatively poor flake alignment that occurs during solution based processing. Here, a scalable method is shown for the fabrication of strong and highly conducting pure MXene films containing highly aligned large MXene flakes. These films demonstrate record tensile strength up to 570 MPa for a 940 nm thick film and electrical conductivity of 15 100 S cm 1 for a 214 nm thick film, which are both the highest values compared to previously reported pure Ti3 C2 Tx films. These films also exhibit outstanding EMI shielding performance (50 dB for a 940 nm thick film) that exceeds other synthetic materials with comparable thickness. MXene films with aligned flakes provide an effective route for producing large area, high strength, and high electrical conductivity MXene based films for future electronic applications.

title: Anomalous absorption of electromagnetic waves by 2D transition metal carbonitride Ti3CNTx (MXene)
abstract: Shields up! Specialized conductive materials are used to shield or block electromagnetic radiation such as microwaves or radio waves to either prevent the escape of stray radiation or prevent interference from unwanted sources. Ideal materials should show high effective shielding while requiring a small volume or mass of material. Materials from the MXene family of two dimensional ceramics, where M is a transition metal and X is either carbon or nitrogen, have shown excellent shielding properties. Iqbal et al. now show even better and somewhat unexpected performance from a metal carbon nitride. Science, this issue p. 446 Heating a layered titanium carbonitride improves conductivity and porosity, removes impurities, and increases electromagnetic interference shielding. Lightweight, ultrathin, and flexible electromagnetic interference (EMI) shielding materials are needed to protect electronic circuits and portable telecommunication devices and to eliminate cross talk between devices and device components. Here, we show that a two dimensional (2D) transition metal carbonitride, Ti3CNTx MXene, with a moderate electrical conductivity, provides a higher shielding effectiveness compared with more conductive Ti3C2Tx or metal foils of the same thickness. This exceptional shielding performance of Ti3CNTx was achieved by thermal annealing and is attributed to an anomalously high absorption of electromagnetic waves in its layered, metamaterial like structure. These results provide guidance for designing advanced EMI shielding materials but also highlight the need for exploring fundamental mechanisms behind interaction of electromagnetic waves with 2D materials.

title: Electromagnetic Shielding of Monolayer MXene Assemblies.
abstract: Miniaturization of electronics demands electromagnetic interference (EMI) shielding of nanoscale dimension. The authors report a systematic exploration of EMI shielding behavior of 2D Ti3 C2 Tx MXene assembled films over a broad range of film thicknesses, monolayer by monolayer. Theoretical models are used to explain the shielding mechanism below skin depth, where multiple reflection becomes significant, along with the surface reflection and bulk absorption of electromagnetic radiation. While a monolayer assembled film offers 20% shielding of electromagnetic waves, a 24 layer film of 55 nm thickness demonstrates 99% shielding (20 dB) revealing an extraordinarily large absolute shielding effectiveness (3.89 x 106 dB cm2 g 1 This remarkable performance of nanometer thin solution processable MXene proposes a paradigm shift in shielding of lightweight, portable, and compact next generation electronic devices.

title: Ultraflexible and Mechanically Strong Double Layered Aramid Nanofiber Ti3C2Tx MXene/Silver Nanowire Nanocomposite Papers for High Performance Electromagnetic Interference Shielding.
abstract: High performance electromagnetic interference (EMI) shielding materials with ultraflexibility, outstanding mechanical properties and superior EMI shielding performances are highly desirable for modern integrated electronic and telecommunication systems in areas such as aerospace, military, artificial intelligence, smart and wearable electronics. Herein, ultraflexible and mechanically strong aramid nanofiber Ti3C2Tx MXene/Ag nanowire (ANF MXene/AgNW) nanocomposite papers with double layered structures are fabricated via the facile two step vacuum assisted filtration (TVAF) followed by hot pressing approach. The resultant double layered nanocomposite papers with a low MXene/AgNW content of 20 wt% exhibit excellent electrical conductivity of 922.0 S*cm 1, outstanding mechanical properties with tensile strength of 235.9 MPa and fracture strain of 24.8% superior EMI shielding effectiveness (EMI SE) of 48.1 dB and high EMI SE/t of 10688.9 dB*cm 1, benefiting from the highly efficient double layered structures, high performance ANF substrate and extensive hydrogen bonding interactions. Particularly, the nanocomposite papers show the maximum electrical conductivity of 3725.6 S*cm 1 and EMI shielding effectiveness (EMI SE) of ~80 dB at the MXene/AgNW content of 80 wt% with an absorption dominant shielding mechanism owing to the massive ohmic losses in highly conductive MXene/AgNW layer, multiple internal reflections between Ti3C2Tx MXene nanosheets and polarization relaxation of localized defects and abundant terminal groups. Compared with the homogeneously blended ones, the double layered nanocomposite papers possess greater advantages in electrical, mechanical and EMI shielding performances. Moreover, the multifunctional double layered nanocomposite papers exhibit excellent thermal management performances such as high Joule heating temperature at low supplied voltages, rapid response time, sufficient heating stability and reliability. The results indicate that the double layered nanocomposite papers have excellent potential for high performance EMI shielding and thermal management applications in aerospace, military and artificial intelligence, smart and wearable electronics.

title: MXene and MXene based composites: synthesis, properties and environment related applications
abstract: In recent years, a new large family of two dimensional transition metal carbides, carbonitrides, and nitrides, so called MXenes, have grabbed considerable attention, owing to their many fascinating physical and chemical properties that are closely related to the rich diversity of their elemental compositions and surface terminations. In particular, it is easy for MXenes to form composites with other materials such as polymers, oxides, and carbon nanotubes, which further provides an effective way to tune the properties of MXenes for various applications. Not only have MXenes and MXene based composites come into prominence as electrode materials in the energy storage field as is widely known, but they have also shown great potential in environment related applications including electro/photocatalytic water splitting, photocatalytic reduction of carbon dioxide, water purification and sensors, thanks to their high conductivity, reducibility and biocompatibility. In this review, we summarize the synthesis and properties of MXenes and MXene based composites and highlight their recent advances in environment related applications. Challenges and perspectives for future research are also outlined.

title: Compressible, durable and conductive polydimethylsiloxane coated MXene foams for high performance electromagnetic interference shielding
abstract: Lightweight and compressible electromagnetic interference (EMI) shielding polymer nanocomposites are urgently required to solve increasingly serious electromagnetic pollutions. Two dimensional transition metal carbides and nitrides (MXenes) especially Ti3C2Tx, are ideal candidates for constructing highly efficient conduction networks in polymer matrices due to their intriguing layered structure and high electrical conductivity. Herein, compressible and electrically conductive polydimethylsiloxane (PDMS) coated MXene foams are fabricated by preforming three dimensional (3D) MXene aerogel architectures assisted with sodium alginate (SA) followed by coating a thin layer of PDMS to enhance structural stability and durability of the porous architectures. Consequently, the lightweight MXene/SA hybrid aerogel achieves an outstanding conductivity of 2211 S m 1 and a high average EMI shielding efficiency of 70.5 dB. Furthermore, the PDMS coating effectively endows the 3D conductance network with excellent compressibility and durability. The PDMS coated MXene foam with 6.1 wt% of MXene reserves its high EMI shielding efficiency of 48.2 dB after 500 compression release cycles. The lightweight, compressible and conductive PDMS coated MXene foam is thus promising for applications in EMI shielding gaskets, wearable electronics, sensors and other specific areas.