There is an urgent need for developing electromechanical sensor with both ultralow detection limits and ultrahigh sensitivity to promote the progress of intelligent technology. Here we propose a ...strategy for fabricating a soft polysiloxane crosslinked MXene aerogel with multilevel nanochannels inside its cellular walls for ultrasensitive pressure detection. The easily shrinkable nanochannels and optimized material synergism endow the piezoresistive aerogel with an ultralow Young's modulus (140 Pa), numerous variable conductive pathways, and mechanical robustness. This aerogel can detect extremely subtle pressure signals of 0.0063 Pa, deliver a high pressure sensitivity over 1900 kPa
, and exhibit extraordinarily sensing robustness. These sensing properties make the MXene aerogel feasible for monitoring ultra-weak force signals arising from a human's deep-lying internal jugular venous pulses in a non-invasive manner, detecting the dynamic impacts associated with the landing and take-off of a mosquito, and performing static pressure mapping of a hair.
Integrating thermodynamically favorable ethanol reforming reactions with hybrid water electrolysis will allow room‐temperature production of high‐value organic products and decoupled hydrogen ...evolution. However, electrochemical reforming of ethanol has not received adequate attention due to its low catalytic efficiency and poor selectivity, which are caused by the multiple groups and chemical bonds of ethanol. In addition to the thermodynamic properties affected by the electronic structure of the catalyst, the dynamics of molecule/ion dynamics in electrolytes also play a significant role in the efficiency of a catalyst. The relatively large size and viscosity of the ethanol molecule necessitates large channels for molecule/ion transport through catalysts. Perforated CoNi hydroxide nanosheets are proposed as a model catalyst to synergistically regulate the dynamics of molecules and electronic structures. Molecular dynamics simulations directly reveal that these nanosheets can act as a “dam” to enrich ethanol molecules and facilitate permeation through the nanopores. Additionally, the charge transfer behavior of heteroatoms modifies the local charge density to promote molecular chemisorption. As expected, the perforated nanosheets exhibit a small potential (1.39 V) and high Faradaic efficiency for the conversion of ethanol into acetic acid. Moreover, the concept in this work provides new perspectives for exploring other molecular catalysts.
Nanoporous ultrathin bimetallic compound sheets are used as a model catalyst to realize synergistic optimization of ethanol molecular spatial distribution and chemisorption. They exhibit a small potential (1.39 V) and high Faradaic efficiency for acetic acid.
Textile electronics are needed that can achieve strain‐unaltered performance when they undergo irregular and repeated strain deformation. Such strain‐unaltered textile electronics require advanced ...fibers that simultaneously have high functionalities and extreme robustness as fabric materials. Current synthetic nanocomposite fibers based on inorganic matrix have remarkable functionalities but often suffer from low robustness and poor tolerance against crack formation. Here, we present a design for a high‐performance multifunctional nanocomposite fiber that is mechanically and electrically robust, which was realized by crosslinking titanium carbide (MXene) nanosheets with a slide‐ring polyrotaxane to form an internal mechanically‐interlocked network. This inorganic matrix nanocomposite fiber featured distinct strain‐hardening mechanical behavior and exceptional load‐bearing capability (toughness approaching 60 MJ m−3 and ductility over 27%). It retained 100% of its ductility after cyclic strain loading. Moreover, the high electrical conductivity (>1.1 × 105 S m−1) and electrochemical performance (>360 F cm−3) of the nanocomposite fiber can be well retained after subjecting the fiber to extensive (>25% strain) and long‐term repeated (10 000 cycles) dimensional changes. Such superior robustness allowed for the fabrication of the nanocomposite fibers into various robust wearable devices, such as textile‐based electromechanical sensors with strain‐unalterable sensing performance and fiber‐shaped supercapacitors with invariant electrochemical performance for 10 000 strain loading cycles.
An extremely robust and multifunctional nanocomposite fiber is fabricated by introducing a mechanically interlocked network inside the fibrous structure. The fiber obtains strong resistance against structural crack formation and propagation, and the fiber‐based textile electronics show exceptional robustness. The textile‐based electromechanical sensors exhibited strain‐unalterable sensing performance and fiber‐shaped supercapacitors showed invariant electrochemical performance during large and cyclic strain perturbations.
Superelastic carbon aerogels have been widely explored by graphitic carbons and soft carbons. These soft aerogels usually have delicate microstructures with good fatigue resistance but ultralow ...strength. Hard carbon aerogels show great advantages in mechanical strength and structural stability due to the sp3‐C‐induced turbostratic “house‐of‐cards” structure. However, it is still a challenge to fabricate superelastic hard carbon‐based aerogels. Through rational nanofibrous structural design, the traditional rigid phenolic resin can be converted into superelastic hard carbon aerogels. The hard carbon nanofibers and abundant welded junctions endow the hard carbon aerogels with robust and stable mechanical performance, including superelasticity, high strength, extremely fast recovery speed (860 mm s−1), low energy‐loss coefficient (<0.16), long cycle lifespan, and heat/cold‐endurance. These emerging hard carbon nanofiber aerogels hold a great promise in the application of piezoresistive stress sensors with high stability and wide detection range (50 kPa), as well as stretchable or bendable conductors.
A family of hard carbon aerogels with nanofibrous structure templated by various nanofibers is fabricated, displaying robust and stable mechanical performances, including high strength, extremely fast recovery speed (860 mm s−1), and ultralow energy loss coefficient (<0.16). After being compressed for 104 cycles (50% strain), they show only ≈2% plastic deformation and retain ≈93% stress.
The construction of biological proton channel analogues has attracted substantial interest owing to their wide potential in separation of ions, sensing, and energy conversion. Here, metal–organic ...framework (MOF)/polymer heterogeneous nanochannels are presented, in which water molecules are confined to disordered clusters in the nanometer‐sized polymer regions and to ordered chains with unique molecular configurations in the 1D sub‐1‐nm porous MOF regions, to realize unidirectional, fast, and selective proton transport properties, analogous to natural proton channels. Given the nano‐to‐subnano confined water junctions, experimental proton conductivities in the polymer‐to‐MOF direction of the channels are much higher than those in the opposite direction, showing a high rectification up to 500 and one to two orders of magnitude enhancement compared to the conductivity of proton transport in bulk water. The channels also show a good proton selectivity over other cations. Theoretical simulations further reveal that the preferential and fast proton conduction in the nano‐to‐subnano channel direction is attributed to extremely low energy barriers for proton transport from disordered to ordered water clusters. This study opens a novel approach to regulate ion permeability and selectivity of artificial ion channels.
Heterogeneous metal–organic framework (MOF)/polymer nanochannels are constructed, where water molecules are confined to ordered chains with unique molecular configurations in the 1D sub‐1‐nm porous MOF regions and to disordered clusters in the nanometer‐sized polymer regions, to realize unidirectional, fast, and selective proton transport properties, analogous to natural voltage‐gated proton channels.
Porous carbon materials demonstrate extensive applications for their attractive characteristics. Mechanical flexibility is an essential property guaranteeing their durability. After decades of ...research efforts, compressive brittleness of porous carbon materials is well resolved. However, reversible stretchability remains challenging to achieve due to the intrinsically weak connections and fragile joints of the porous carbon networks. Herein, it is presented that a porous all‐carbon material achieving both elastic compressibility and stretchability at large strain from −80% to 80% can be obtained when a unique long‐range lamellar multi‐arch microstructure is introduced. Impressively, the porous all‐carbon material can maintain reliable structural robustness and durability under loading condition of cyclic compressing–stretching process, similar to a real metallic spring. The unique performance renders it as a promising platform for making smart vibration and magnetism sensors, even capable of operating at extreme temperatures. Furthermore, this study provides valuable insights for creating highly stretchable and compressible porous materials from other neat inorganic components for diverse applications in future.
A porous spring‐like all‐carbon material achieving both elastic compressibility and stretchability at large strain from −80% to 80% is obtained when a unique long‐range lamellar multi‐arch microstructure is designed. The excellent mechanical performance combined with the intrinsic advantages of carbon makes it a promising platform for making smart vibration and magnetism sensors that can work at extreme temperatures.
The high fracture toughness of mollusk nacre is predominantly attributed to the structure‐associated extrinsic mechanisms such as platelet sliding and crack deflection. While the nacre‐mimetic ...structures are widely adopted in artificial ceramics, the extrinsic mechanisms are often weakened by the relatively low tensile strength of the platelets with a large aspect ratio, which makes the fracture toughness of these materials much lower than expected. Here, it is demonstrated that the fracture toughness of artificial nacre materials with high inorganic contents can be improved by residual stress‐induced platelet strengthening, which can catalyze more effective extrinsic toughening mechanisms that are specific to the nacre‐mimetic structures. Thereby, while the absolute fracture toughness of the materials is not comparable with advanced ceramic‐based composites, the toughness amplification factor of the material reaches 16.1 ± 1.1, outperforming the state‐of‐the‐art biomimetic ceramics. The results reveal that, with the merit of nacre‐mimetic structural designs, the overall fracture toughness of the artificial nacre can be improved by the platelet strengthening through extrinsic toughening mechanisms, although the intrinsic fracture toughness may decrease at platelet level due to the strengthening. It is anticipated that advanced structural ceramics with exceeding performance can be fabricated through these unconventional strategies.
This work illustrates an anti‐intuitive strategy that, with the merit of biomimetic designs, residual stress that is conventionally harmful to ceramics can inversely help improve the fracture toughness of biomimetic ceramics through nanoscale residual stress‐induced platelet strengthening. This provides new insights into the design principles of nacre‐like materials at the bottom level.
Low-density compressible materials enable various applications but are often hindered by structure-derived fatigue failure, weak elasticity with slow recovery speed and large energy dissipation. Here ...we demonstrate a carbon material with microstructure-derived super-elasticity and high fatigue resistance achieved by designing a hierarchical lamellar architecture composed of thousands of microscale arches that serve as elastic units. The obtained monolithic carbon material can rebound a steel ball in spring-like fashion with fast recovery speed (∼580 mm s
), and demonstrates complete recovery and small energy dissipation (∼0.2) in each compress-release cycle, even under 90% strain. Particularly, the material can maintain structural integrity after more than 10
cycles at 20% strain and 2.5 × 10
cycles at 50% strain. This structural material, although constructed using an intrinsically brittle carbon constituent, is simultaneously super-elastic, highly compressible and fatigue resistant to a degree even greater than that of previously reported compressible foams mainly made from more robust constituents.
The emerging aramid‐mica nanopapers, composed of aramid nanofibers (ANFs) and mica nanosheets (Mica), exhibit superiority in the field of electrical insulation compared with commercial aramid‐mica ...micropapers. Unfortunately, their mechanical and electrical insulating properties are still less than ideal due to insufficient control of their microstructures. Herein, it is presented that by integrating ANFs and Mica into nacre‐like aramid‐mica nanopapers with improved structural orderliness, densification, and interlayer interaction, simultaneously improved mechanical and electrical insulating properties are achieved. Their maximum tensile strength and breakdown strength reach ≈292 MPa and ≈176 kV mm−1, respectively, which are superior to those of the state‐of‐the‐art ANFs‐based nanopapers. Particularly, the aramid‐mica nanopapers show high resistance to high‐temperature (250–300 °C) and oil‐bath (100 °C) environments commonly involved in practical applications, and can be recycled many times, demonstrating their great potential as high‐performance sustainable electrical insulating papers to be applied in advanced electrical equipment.
The aramid‐mica nanopapers with simultaneously and greatly enhanced mechanical and electrical insulating properties are fabricated by assembling aramid nanofibers and mica nanosheets into nacre‐like structures with improved structural orderliness, densification, and interlayer interaction. Particularly, this nanopaper shows high resistance to high‐temperature (250–300 °C) and oil‐bath (100 °C) environments commonly involved in practical applications, and can be recycled many times.
Electronic skin (e‐skin) capable of acquiring environmental and physiological information has attracted interest for healthcare, robotics, and human–machine interaction. However, traditional 2D ...e‐skin only allows for in‐plane force sensing, which limits access to comprehensive stimulus feedback due to the lack of out‐of‐plane signal detection caused by its 3D structure. Here, a dimension‐switchable bioinspired receptor is reported to achieve multimodal perception by exploiting film kirigami. It offers the detection of in‐plane (pressure and bending) and out‐of‐plane (force and airflow) signals by dynamically inducing the opening and reclosing of sensing unit. The receptor's hygroscopic and thermoelectric properties enable the sensing of humidity and temperature. Meanwhile, the thermoelectric receptor can differentiate mechanical stimuli from temperature by the voltage. The development enables a wide range of sensory capabilities of traditional e‐skin and expands the applications in real life.
A flexible multimodal receptor can achieve a reversible transformation from 2D to 3D structure by bending or stretching the sensor, drawing inspiration from the morphological switch observed in the hummingbird feathers. Interestingly, a single‐unit receptor is capable of sensing multiple stimuli, including in‐plane deformation (pressure and bending), out‐of‐plane deformation (force and airflow), temperature, and humidity.
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