Sequentially bridged MXene platelets for strong high‐temperature EM‐IR bi‐stealth sheets

Combination of flexible multifunctional stealth technology properties such as electromagnetic(EM)and infrared(IR)stealth is crucial to the development of aerospace,military,and electronic fields,but the synthesis technology still has a significant challenge.Herein,we have successfully designed and synthesized highly flexible MXene@cellulose lamellae/borate ion(MXCB)sheets with strong high‐temperature EM‐IR bi‐stealth through sequential bridging of hydrogen and covalent bonds.The resultant MXCB sheets display high conductivity and good mechanical features such as flexibility,stretchability,fatigue resistance,and ultrasonic damage.MXCB sheets have a high tensile strength of 795 MPa.Furthermore,MXCB sheets with different thicknesses indicate exceptional high‐temperature thermal‐camouflage characteristics.This reduces the radiation temperature of the target object(>300°C)to 100°C.The conductivity of MXCB sheet with 3μm thickness is 6108 S/cm and the EM interference(EMI)shielding value is 39.74 dB.The normalized surface‐specific EMI SE absolute shielding effectiveness(SSE/t)is as high as 39312.78 dB·cm2/g,which remained 99.39%even after 10,000 times repeated folding.These multifunctional ultrathin MXCB sheets can be arranged by vacuum‐assisted induction to develop EM‐IR bi‐stealth sheet.

A biomimetic-structured wood-derived carbon sponge with highly compressible and biocompatible properties for human-motion detection

Piezoresistive sensors,as an indispensable part of electronic and intelligent wearable devices,are often hindered by nonrenewable resources(graphene,conventional metal,or silicon).Biomass-derived carbonaceous materials boast many advantages such as their light weight,renewability,and excellent chemical stabilization.However,a major challenge is that the strength and resilience of carbon-based piezoresistive materials still falls short of requirements due to their random microarchitectures which cannot provide sufficiently good stress distribution.Encouraged by the excellent compressible properties and extraordinary strength of the Thalia dealbata stem,we propose a wood biomassderived carbon piezoresistive sensor with an artificial interconnected lamellar structure like the stem itself.By introducing a freezing-induced assembly process,a wood-based,completely delignified,nano-lignocellulose material can be built into a“bridges supported lamellar”type architecture,where subsequent freeze-drying and pyrolysis results in carbon aerogel monoliths.The resultant bioinspired carbon sponge has high compressibility and strength,of the order of two to five times higher than that of conventional metal,carbon,and organic materials.Combined with excellent biocompatible properties and chemical durability,these are useful properties for intelligent wearable devices and human-motion detection.