Although multifunctional, flexible, and wearable textiles with integrated smart electronics have attracted tremendous attention in recent years, it is still an issue to balance new functionalities with the inherent performances of the textile substrates. 2D early transition metal carbides/nitrides (MXenes) are considered as ideal nanosheets for fabricating multifunctional and flexible textiles on the basis of their superb intrinsic electrical conductivity, tunable surface chemistry, and layered structure. Herein, highly conductive and hydrophobic textiles with exceptional electromagnetic interference (EMI) shielding efficiency and excellent Joule heating performance are fabricated by depositing in situ polymerized polypyrrole (PPy) modified MXene sheets onto poly(ethylene terephthalate) textiles followed by a silicone coating. The resultant multifunctional textile exhibits high electrical conductivity of ≈1000 S m −1 in conjunction with an exceptional EMI shielding efficiency of ≈90 dB at a thickness of 1.3 mm. The thin silicone coating renders the hydrophilic PPy/MXene-decorated textile hydrophobic, leading to an excellent water-resistant feature while retaining a satisfactory air permeability of the textile. Interestingly, the multifunctional textile also exhibits an excellent mode rate voltage-driven Joule heating performance. Thus, the deposition of PPy-modified MXene followed by silicone coating creates a multifunctional textile that holds great promise for wearable intelligent garments, EMI shielding, and personal heating applications.

Highly conductive polymer nanocomposites are greatly desired for electro magnetic interference (EMI) shielding applications. Although transition metal carbide/carbonitride (MXene) has shown its huge potential for producing highly conductive films and bulk materials, it still remains a great challenge to fabricate extremely conductive polymer nanocomposites with outstanding EMI shielding performance at minimal amounts of MXenes. Herein, an electrostatic assembly approach for fabricating highly conductive MXene@ polystyrene nanocomposites by electrostatic assembling of negative MXene nanosheets on positive polystyrene microspheres is demonstrated, fol lowed by compression molding. Thanks to the high conductivity of MXenes and their highly efficient conducting network within polystyrene matrix, the resultant nanocomposites exhibit not only a low percolation threshold of 0.26 vol% but also a superb conductivity of 1081 S m −1 and an outstanding EMI shielding performance of >54 dB over the whole Xband with a max imum of 62 dB at the low MXene loading of 1.90 vol%, which are among the best performances for electrically conductive polymer nanocomposites by far. Moreover, the same nanocomposite has a highly enhanced storage modulus, 54% and 56% higher than those of neat polystyrene and conven tional MXene@polystyrene nanocomposite, respectively. This work provides a novel methodology to produce highly conductive polymer nanocomposites for highly efficient EMI shielding applications.

2D transition metal carbides and nitrides (MXenes) have gained extensive attention recently due to their versatile surface chemistry, layered structure, and intriguing properties. The assembly of MXene sheets into macroscopic architectures is an important approach to harness their extraordinary properties. However, it is difficult to construct a freestanding, mechanically flexible, and 3D framework of MXene sheets owing to their weak intersheet interactions. Herein, an interfacial enhancement strategy to construct multifunctional, superelastic, and lightweight 3D MXene architectures by bridging individual MXene sheets with polyimide macromolecules is developed. The resulting lightweight aerogel exhibits superelasticity with large reversible compressibility, excellent fatigue resistance (1000 cycles at 50% strain), 20% reversible stretchability, and high electrical conductivity of ≈4.0 S m−1. The outstanding mechanical flexibility and electrical conductivity make the aerogel promising for damping, microwave absorption coating, and flexible strain sensor. More interestingly, an exceptional microwave absorption performance with a maximum reflection loss of −45.4 dB at 9.59 GHz and a wide effective absorption bandwidth of 5.1 GHz are achieved.

A covalent organic framework integrating naphthalenediimide and triphenylamine units (NT-COF) is presented. Two-dimensional porous nanosheets are packed with a high specific surface area of 1276 m g . Photo/electrochemical measurements reveal the ultrahigh efficient intramolecular charge transfer from the TPA to the NDI and the highly reversible electrochemical reaction in NT-COF. There is a synergetic effect in NT-COF between the reversible electrochemical reaction and intramolecular charge transfer with enhanced solar energy efficiency and an accelerated electrochemical reaction. This synergetic mechanism provides the key basis for direct solar-to-electrochemical energy conversion/storage. With the NT-COF as the cathode materials, a solar Li-ion battery is realized with decreased charge voltage (by 0.5 V), increased discharge voltage (by 0.5 V), and extra 38.7 % battery efficiency.

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Titanium carbide (Ti3C2Tx) MXene has great potential for use in aerospace and flexible electronics due to its excellent electrical conductivity and mechanical properties. However, the assembly of MXene nanosheets into macroscopic high-performance nanocomposites is challenging, limiting MXene’s practical applications. Here we describe our work fabricating strong and highly conductive MXene sheets through sequential bridging of hydrogen and ionic bonding. The ionic bonding agent decreases interplanar spacing and increases MXene nanosheet alignment, while the hydrogen bonding agent increases interplanar spacing and decreases MXene nanosheet alignment. Successive application of hydrogen and ionic bonding agents optimizes toughness, tensile strength, oxidation resistance in a humid environment, and resistance to sonication disintegration and mechanical abuse. The tensile strength of these MXene sheets reaches up to 436 MPa. The electrical conductivity and weight-normalized shielding efficiency are also as high as 2,988 S/cm and 58,929 dB∙cm2/g, respectively. The toughening and strengthening mechanisms are revealed by molecular-dynamics simulations. Our sequential bridging strategy opens an avenue for the assembly of other high-performance MXene nanocomposites.

Here we report a non-toxic β-type titanium alloy exhibiting unstable elastic and plastic deformation behavior. Elastic instability leads to remarkable elastic softening, i.e., the decrease of incipient Young’s modulus with slight pre-straining. In spite of partial recovery during room-temperature aging, a stable modulus of 33GPa matching that of human bone can be maintained. Plastic instability causes highly-localized deformation which is very effective in grain refinement but contributes little to strength. We thus obtain soft nanostructured metallic materials (NMMs): The flow stress increases by only ∼5.5% as coarse grains are reduced to below 50nm, in contrast with several times increase for previously-reported NMMs.

Carbon spheres appeared for the first time during the process of etching Ti3AlC2 using hydrofluoric acid.