MXene Aerogel Research Articles

Fully Integrated Biosensing System for Dynamic Monitoring of Sweat Glucose and Real-Time pH Adjustment Based on 3D Graphene MXene Aerogel.

The development of noninvasive glucose sensors capable of continuous monitoring without restricting user mobility is crucial, particularly for managing diabetes, which demands consistent and long-term observation. Traditional sensors often face challenges with accuracy and stability that curtail their practical applications. To address these issues, we have innovatively applied a three-dimensional porous aerogel composed of Ti3C2Tx MXene and reduced graphene oxide (MX-rGO) in electrochemical sensing. It significantly reduces the electron-transfer distance between the enzyme's redox center and the electrode surface while firmly anchoring the enzyme layer to effectively prevent any leakage. Another pivotal advancement in our study is the integration of the sensor with a real-time adaptive calibration mechanism tailored specifically for analyzing sweat glucose. This sensor not only measures glucose levels but also dynamically monitors and adjusts to pH fluctuations in sweat. Such capabilities ensure the precise delivery of physiological data during physical activities, providing strong support for personalized health management.

Fe3O4@MXene@PEI aerogel immobilized acetylcholinesterase for inhibitor screening from herbal plants

Screening of acetylcholinesterase (AChE) inhibitors is a common strategy in drug discovery for treating Alzheimer’s disease. Herein, AChE was immobilized onto magnetic polyethyleneimine-based MXene aerogels through both electrostatic interactions and covalent bonds, enabling its application in AChE activity assays and inhibitor screening of herbal plants. The composite was analyzed using a range of techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and Zeta potential analysis, to gain insight into its chemical and physical properties. The proposed Fe3O4@MXene@PEI-AChE composite exhibited enhanced temperature and pH stability, as evaluated by Ellman’s method, along with good reusability. The Michaelis Menten constant (Km) of the immobilized AChE was calculated to be 0.68 mmol/L. Additionally, an inhibition kinetic study was conducted to verify the feasibility of utilizing the immobilized enzyme to screen for inhibitors, with huperzine A employed as a model inhibitor. The proposed strategy was employed to compare the AChE inhibitory activity of 18 commonly used herbal medicines for treating AD, revealing both the aqueous and alcoholic extracts of Coptis chinensis as exhibiting the highest AChE inhibitory activity. Finally, the screening of AChE inhibitors in Coptis chinensis extracts were conducted by combining the proposed strategy with UPLC-Q-Orbitrap high resolution mass spectrometry. This study presents a feasible strategy for monitoring AChE activity and holds considerable potential for further exploration of AChE-inhibiting active ingredients in herbal medicines.

Unlocking versatile capabilities: Mixed-valence decavanadate aerogels for boosting radar, infrared, and thermal stealth

Multifunctional compatible stealth materials have emerged as the focal point of contemporary protection technology research and vanadium-based nanomaterials play a pivotal role in the development of advanced stealth materials. Here, a compatible stealth aerogel is successfully synthesized by employing mixed-valence decavanadate as the vanadium oxide (VOx) molecular model. Ultralight {VⅣVV9}/MXene aerogel (0.0429 g cm–3) exhibits exceptional radar stealth performance with a minimal reflection loss (RLmin) of −57.74 dB (99.9998% EMW absorption) and a significantly superior radar cross section reduction value of 26.77 dB m2. The aerogel's exceptional properties, including a low infrared (IR) emissivity (0.479) and a low thermal conductivity of (32.30 mW m–1 K–1), are crucial for enabling compatibility with IR and thermal stealth technologies. The presence of a mixed-valence polyoxovanadate cluster leads to an increase in the Schottky barrier and enhances magnetic properties, consequently boosting interfacial polarization and contributing to magnetic losses during electromagnetic wave (EMW) absorption. Consequently, altering the number of valence electrons significantly enhances the compatible stealth capabilities. These findings contribute significantly to our comprehension of how microstructure impacts EMW absorption processes and provide a basis for further research into the development of VOx-based compatible stealth materials.

Layer-by-layer assembled aramid nanofiber/MXene aerogel: Exceptional resistance to extreme temperatures and robust anisotropy for advanced applications

Aerogels are characterized with unique morphology and physical properties, thus are serving as essential elements in advanced applications. Nowadays, the delicate intelligent devices are frequently exposed in harsh environments, leading to multiple issues during application of functional aerogels including the limited resistance to extreme temperatures, requiring encapsulation prior to usage, and accumulation of Joule heat. In this study, we fabricated a multilayered aramid nanofiber (ANF)/MXene aerogel with the layer-by-layer stacking ANF and ANF/MXene layers. Attributing to the multilayered and porous structure, the aerogel displayed proper EMI shielding performance which maintained stable in harsh environments of excessive high temperature (200 °C) and low temperature (−196 °C). More importantly, obvious anisotropy in electrical conductivity (∼8 orders of magnitude) and thermal insulation (ΔT = 32 °C) was obtained along the in-plane and out-of-plane directions. As two demonstrations of potential applications, the sensing performance and thermal insulating property of the ANF/MXene aerogel was displayed. Inspiringly, the aerogel sensor exhibited significant durability and notable sensitivity to different deformations. Also, the aerogel displayed rapid heat dissipation along the in-plane direction while efficient thermal insulation along the out-of-plane direction, thus, can be applied in thermal management to protect the electronic devices. Therefore, the as-prepared ANF/MXene aerogel can serve as EMI shielding parts, encapsulation-free flexible electronics as compression sensor and anisotropic thermal insulator, which has great potential in the application of intelligent devices.

Oriented structural design of MXene electrodes for lithium sulfur catalysis

The lithium-sulfur reaction can contribute to the chemical electrical energy conversion capacity due to the multi-level ion/electron transfer process. However, the appearance of soluble intermediate products prevents efficient electron transfer, making it impossible to achieve stable cycling and capacity contribution. Restricted catalysis provides a solution for inhibiting the shuttle of soluble lithium polysulfides. Herein, MXene aerogel with optimized channel utilization is designed as S host according to the polysulfide control strategy of localization, adsorption, and catalysis. With the help of the results of oriented channels, the polysulfide conversion process is optimized, providing a comprehensive scheme for inhibiting the shuttle effect. Lithium sulfur catalytic batteries have achieved high capacity and stable cycling. This system provides a comprehensive solution for lithium sulfur reaction catalysis and a new perspective for the functional application of MXene based lithium sulfur batteries.

Machine intelligence accelerated design of conductive MXene aerogels with programmable properties

Designing ultralight conductive aerogels with tailored electrical and mechanical properties is critical for various applications. Conventional approaches rely on iterative, time-consuming experiments across a vast parameter space. Herein, an integrated workflow is developed to combine collaborative robotics with machine learning to accelerate the design of conductive aerogels with programmable properties. An automated pipetting robot is operated to prepare 264 mixtures of Ti3C2Tx MXene, cellulose, gelatin, and glutaraldehyde at different ratios/loadings. After freeze-drying, the aerogels’ structural integrity is evaluated to train a support vector machine classifier. Through 8 active learning cycles with data augmentation, 162 unique conductive aerogels are fabricated/characterized via robotics-automated platforms, enabling the construction of an artificial neural network prediction model. The prediction model conducts two-way design tasks: (1) predicting the aerogels’ physicochemical properties from fabrication parameters and (2) automating the inverse design of aerogels for specific property requirements. The combined use of model interpretation and finite element simulations validates a pronounced correlation between aerogel density and compressive strength. The model-suggested aerogels with high conductivity, customized strength, and pressure insensitivity allow for compression-stable Joule heating for wearable thermal management.

Selective extraction and analysis of phenolic acids in herbal plants using Fe3O4@MXene@PEI aerogel

A magnetic MXene aerogel (Fe3O4@MXene@PEI) was prepared by crosslinking amino modified MXene with polyethyleneimine using epichlorohydrin as a cross-linker. Adsorption properties of Fe3O4@MXene@PEI aerogel for phenolic acids were evaluated by adsorption kinetics and isotherms experiments, showing that the high adsorption affinity was governed by multilayer chemisorption process. An efficient MSPE/HPLC method was developed for the determination of phenolic acids with excellent selectivity, good linearity (0.025–5.0 μg mL−1), low LODs (0.007–0.017 μg mL−1), and satisfactory recoveries (80.0–120.0 %). Moreover, the antioxidant activity of the Fe3O4@MXene@PEI purified compounds was superior to that of the conventional method as demonstrated by the results of scavenging experiments on 2,2 -diphenyl-1-picrylhydrazyl radical scavenging assay. Finally, 65 organic acids were identified in the Fe3O4@MXene@PEI treated honeysuckle extracts by UHPLC-Q-Exactive Orbitrap MS/MS analysis. The proposed sorbent exhibits remarkable promise for the selective separation and purification of organic acids from herbal products.

One‐Hour Ambient‐Pressure‐Dried, Scalable, Stretchable MXene/Polyurea Aerogel Enables Synergistic Defense Against High‐Frequency Mechanical Shock and Electromagnetic Waves

AbstractThe rapid, energy‐efficient, scalable preparation of high‐strength, flexible, multifunctional nanostructured aerogels is highly desired yet challenging. Here, an ambient‐pressure‐dried (APD) strategy is developed involving self‐foaming, dip‐coating, and graphene oxide (GO)‐assisted multiple cross‐linking treatments for the prompt, large‐area preparation of polyurea/transition metal carbides/nitrides (MXenes) aerogels. The APD MXene‐based aerogels showcase low density, remarkable mechanical strength, and ultraflexiblity involving stretchability, good conductivity, hydrophobicity, and high resistance to various solvents. Synergies of robust, elastic cell walls and porous structure contribute to high‐efficiency absorption of high‐frequency, high‐speed mechanical shock waves for the aerogels, significantly transcendinging the biomasses, plastics, elastomers, ceramics, and metals. In addition to the excellent microwave shielding performance of over 40 dB in ultrabroadband frequencies of 4–40 GHz, the oxidation stability is elevated for APD MXene aerogels, consequently yielding applicability in harsh conditions. Furthermore, the superior light absorption capability of aerogels leads to the efficient photothermal conversion, therapy, antibacterial, desalination, water purification, deicing, and thick oil absorption. This work provides a facile, time‐ and energy‐efficient, scalable APD methodology for manufacturing large‐area, high‐strength, ultraflexible, multifunctional MXene‐based aerogels, enlighting a novel synergistic defense against mechanical shock and electromagnetic waves, and promoting them as a prospective candidate in aerospace, device protection, and next‐generation electronics.

Multifunctional graphene/Ti3C2Tx MXene aerogel inlaid with Ni@TiO2 core-shell microspheres for high-efficiency electromagnetic wave absorption and thermal insulation

The demand for high-performance electromagnetic wave absorbing (EMA) materials featured with strong attenuation ability, extended absorption bandwidth and ultralight property is imperative yet remains challenging. Herein, a three-dimensional hierarchically porous reduced graphene oxide (rGO)/Ti3C2Tx MXene aerogel embedded with Ni@TiO2 core–shell microspheres was prepared via directional freeze-drying followed by a mild annealing process. The divergence in structure and multicomponent dielectric/magnetic features bring about optimized impedance matching characteristic, multiple polarization and loss pathways, collectively contributing to the excellent absorption performance. As a result, the Ni@TiO2/MXene/rGO (NTMRG-2) aerogel exhibits optimized EMA capability with a maximal effective absorption bandwidth (EABmax) of 6.48 GHz at a lower loading level of 5 wt% in the supporting matrix, covering the whole Ku band. Additionally, it achieves a minimum reflection loss (RLmin) of −71.4 dB with a matching thickness of 2.04 mm. Moreover, the aerogel also exhibits an ultra-light density of 5.58 mg cm−3, superior thermal insulation capacity (close to air) and hydrophobicity, underscoring its potential for multiple applications in various scenarios.

Dual Cross‐Linked Magnetic MXene Aerogel with High Strength and Durability Enables Multifunctionality

AbstractThe construction of lightweight yet robust, durable magnetic transition metal carbides and/or nitride (MXene) aerogels is highly desired for assembling high‐performance, multifunctional architectures. However, the fabrication and application of magnetic MXene aerogels is severely restricted by their inferior mechanical strength and poor water/oxygen resistance. Here, sustainable cellulose nanofibrils (CNFs) are employed for assisting in the physical and chemical dual cross‐linking to strongly bind the MXenes and MOF‐derived magnetic nanoparticles. The dual‐crosslinked magnetic MXene aerogels (D‐MMAs) achieve a density as low as 12 mg cm−3, and acquire a significantly improved mechanical strength of up to 1311% over physically crosslinked ones, as well as remarkably improved hydrophobicity, and oxidation stability. Furthermore, the multifunctional integration of efficient and tunable electromagnetic wave (EMW) absorption, remarkable photothermal conversion, thermal insulation, prominent oil‐water separation, thin/thick oil and dye absorption capability, and the remote magnetic controllability is accomplished. Notably, the D‐MMA performs a maximum absorption intensity of −63.9 dB, and accomplishes a specific reflection loss of −1105 dB mm−1, comparable to the best MXene‐based EMW absorbers ever reported. Given its facile, scalable, and sustainable manufacturing approach, the multifunctional D‐MMAs hold great application prospects in various fields of next‐generation electronics, special equipment protection, defense, and aerospace.

Cation-induced Ti3C2Tx MXene@melamine sponge aerogels with large layer spacing and high strength for high-performance supercapacitors

The self-assembled aerogels are considered as an efficient strategy to address the aggregation and restacking of Ti3C2Tx MXene nanosheets for high-performance supercapacitors. However, the low mechanical strength of the MXene aerogel results in the structural collapse of the self-standing supercapacitor electrode materials. Herein, a low-cost melamine sponge (MS) absorbed different cations (H+, K+, Mg2+, Fe2+, Co2+, Ni2+ and Al3+), serves as a carrier and crosslinker for loading MXene hydrogel induced by the absorbed cations on the skeleton surface and the pores of MS, resulting in the high loading mass MXene aerogels with high mechanical strength. The experimental results show that the Mg-Ti3C2Tx@MS aerogel exhibits the maximum area capacitance of 702.22 mF cm−2 at 3 mA cm−2, and the area capacitance is still 603.12 mF cm−2 even at 100 mA cm−2, indicating the high rate capability with a capacitance retention of 85.89 %. It is worth noting that the constructed asymmetric supercapacitor with activated carbon achieves high energy densities of 104.53 μWh cm−2 and 93.87 μWh cm−2 at 800 μW cm−2 and 7999 μW cm−2, respectively. Furthermore, the asymmetric supercapacitor shows the high cycling stability with 90.2 % capacity retention after 10,000 cycles. This work provides a feasible strategy to prepare Ti3C2Tx MXene aerogels with large layer spacing and high strength for high-performance supercapacitors.

MXene/BC@CoFe2O4 aerogel with excellent electromagnetic interference shielding and enhanced mechanical property

As electromagnetic radiation gradually increases, electromagnetic shielding becomes increasingly crucial. In the field of electromagnetic interference shielding, MXene aerogels have gradually attracted attention. However, the applicability of MXene aerogels is limited due to their poor mechanical and electromagnetic shielding capabilities. To address these issues, a hybrid aerogel, MXene/BC@CoFe2O4, was created using in-situ growth and single-directional freeze-drying methods. By generating CoFe2O4 magnetic nanoparticles on the surface of BC and using BCFO composite cellulose to modulate the electromagnetic interference shielding effectiveness (EMI SE) of MXene aerogel, the EMI SE of MXene/BC@CoFe2O4 aerogel reached 82.5 dB. In comparison to MXene aerogel, the compressive stress of MBCA is increased by 3.6 times, and BC@CoFe2O4 composite cellulose also improves the mechanical properties of MXene aerogel. The synthesized MXene/BC@CoFe2O4 aerogel demonstrates outstanding electromagnetic shielding performance and enhanced mechanical properties, presenting significant potential applications in aerospace and electrical equipment industries.

Mechanically robust and multifunctional Ti3C2Tx MXene composite aerogel for broadband EMI shielding

Because of its high electrical conductivity and low density, Ti3C2Tx MXene aerogel is thought to be a promising electromagnetic interference (EMI) shielding material. However, it is suffering from high reflection shielding and poor mechanical strength, which naturally hinders its practical application. Herein, we constructed PDMS-encapsulated Fe3O4/multi-walled carbon nanotubes (MWCNTs)/Ti3C2Tx MXene aerogel by combining the bi-directional freeze-drying technique with vacuum impregnation. The lamellar porous architecture and rational components endow the PDMS-encapsulated composite aerogel with superior EMI shielding properties in the X- and Ku-bands. Specifically, the optimal total shielding effectiveness (SET) of the PDMS-encapsulated composite aerogel (3 mm) could reach 43.6 dB, whereas the corresponding reflection shielding effectiveness (SER) is only 7 dB (approximately 16.7 % of SET). The shielding mechanism was also comprehensively disclosed. Simultaneously, contributed by the synergistic effect of lamellar porous structure and PDMS, the PDMS-encapsulated composite aerogel possesses satisfactory compressive strength (28.62 MPa) and tensile strength (1.67 MPa). Additionally, the PDMS-encapsulated composite aerogel also exhibits promising applications in thermal insulation.

A Sweat Absorbing Skin Electrode for Electrophysiology During Exercise

AbstractElectrophysiological signals are commonly used to assess health performance, providing valuable information on body status. However, stable signal acquisition by commercial Ag/AgCl gel or metal electrodes is susceptible to electrode/skin interface interferences due to perspiration and motion during exercise. To address this challenge, herein a sweat absorbing skin electrode (SAE) is designed, which can not only become softer and more adhesive but also enhance conductivity after sweat during exercise. The resulting stable interface between SAE/skin after sweat enables accurate and continuous electrophysiological measurement during exercise. SAE is demonstrated by assembly of MXene (Ti3C2TX) aerogel and zwitterionic polymer, where Ti3C2TX aerogel works as conductive skeleton and zwitterionic polymer endows skin conformability as well as expediting interfacial charge transfer by the inherent ions. SAE can monitor a variety of electrophysiological signals during exercise. As an example, electromyogram (EMG) signals are acquired to assess muscle fatigue, which is impossible by commercial gel electrodes. Via machine learning, the correlation between EMG and physiological markers (body fat percentage (BF) and body mass index (BMI)) are constructed. The research shows that sweat‐absorbing SAEs can reliably monitor electrophysiological signals during exercise, such as muscle status, leading to evidence‐based scientific guidelines for sports and rehabilitation training.

Biomimetic Dual Absorption-Adsorption Networked MXene Aerogel-Pump for Integrated Water Harvesting and Power Generation System.

Harvesting atmospheric water and converting it into electricity play vital roles in advancing next-generation energy conversion systems. However, the current water harvester systems suffer from a weak water capture ability and poor recyclability due to high diffusion barriers and low sorption kinetics, which significantly limit their practical application. Herein, we drew inspiration from the natural "Pump effect" observed in wood and successfully developed a dual "absorption-adsorption" networked MXene aerogel atmospheric water harvester (MAWH) through ice templating and confining LiCl processes, thereby serving multiple purposes of clean water production, passive dehumidification, and power generation. The MAWH benefits from the dual H-bond network of MXene and cellulose nanocrystals (absorption network) and the hygroscopic properties of lithium chloride (adsorption network). Furthermore, its aligned wood-like channel structure efficiently eliminates water nucleation near the 3D network, resulting in fast moisture absorption. The developed MAWH demonstrates a high moisture absorption ability of 3.12 g g-1 at 90% relative humidity (RH), featuring rapid vapor transport rates and durable cyclic performance. When compared with commercial desiccants such as the 4A molecular sieve and silica gel, the MAWH can reduce the RH from 80% to 20% within just 6 h. Most notably, our integrated MAWH-based water harvesting-power generation system achieves a high voltage of ∼0.12 V at 77% RH, showcasing its potential for practical application. These developed MAWHs are considered as high-performance atmospheric water harvesters in the water collection and power generation field.

Ti3C2Tx MXene reinforcement: a nickel-vanadium selenide/MXene based multi-component composite as a battery-type electrode for supercapacitor applications.

Designing innovative microstructures and implementing efficient multicomponent strategies are still challenging to achieve high-performance and chemo-mechanically stable electrode materials. Herein, a hierarchical three-dimensional (3D) graphene oxide (GO) assisted Ti3C2Tx MXene aerogel foam (MXene-GAF) impregnated with battery-type bimetallic nickel vanadium selenide (NiVSe) has been prepared through a hydrothermal method followed by freeze-drying (denoted as NiVSe-MXene-GAF). 3D-oriented cellular pore networks benefit the energy storage process through the effective lodging of NiVSe particles, improving the access of the electrolyte to the active sites, and alleviating volume changes during redox reactions. The 3D MXene-GAF conductive matrix and heterostructured interface of MXene-rGO and NiVSe facilitated the rapid transport of electrical charges and ions during the charge-discharge process. As a result of the synergism of these effects, NiVSe-MXene-GAF exhibited remarkable electrochemical performance with a specific capacity of 305.8 mA h g-1 at 1 A g-1 and 99.2% initial coulombic efficiency. The NiVSe-MXene-GAF electrode delivered a specific capacity of 235.1 mA h g-1 even at a high current density of 12 A g-1 with a 76.8% rate performance. The impedance measurements indicated a low bulk solution resistance (Rs = 0.71 Ω) for NiVSe-MXene-GAF. Furthermore, the structural robustness of NiVSe-MXene-GAF guaranteed long-term stability with a 91.7% capacity retention for successive 7000 cycles. Thus, developing NiVSe-MXene-GAF provides a progressive strategy for fabricating high-performance 3D heterostructured electrode materials for energy storage applications.

Self-Assembly of Binderless MXene Aerogel for Multiple-Scenario and Responsive Phase Change Composites with Ultrahigh Thermal Energy Storage Density and Exceptional Electromagnetic Interference Shielding

HighlightsThis work proposes a tactic for improving the efficiency of thermal energy conversion and expanding the application scenarios of phase change materials by constructing non-binder and oriented MXene-K+ aerogel.The prepared phase change composites (PCCs) can rapidly transform solar, electric, magnetic energy into latent heat for keeping warm, power generation, and thermal physiotherapy.Owing to the suggested tactic, the prepared PCCs achieves ultrahigh energy storage density and realize 99.9998% electromagnetic wave energy attenuation.

Universal pathway towards metal sulfides decorated 3D porous Ti3C2Tx MXene aerogel for vapor-phase mercury removal

Utilization of monolithic mineral sulfide-based sorbent for the fix-bed elemental mercury (Hg0) removal is regarded as a predominant predicament in the field of Hg0 abatement. In this work, a general and facile route was exploited to establish CuS particles decorated 3D porous Ti3C2Tx MXene aerogel via divalent Cu2+ cations induced assembly combined with subsequent high-temperature sulfurization treatment, during which, uniform CuS particles were homogeneously anchored throughout the Ti3C2Tx substrate. The obtained 3D CuS/Ti3C2Tx MXene aerogel exhibited satisfactory textural property, hierarchical pore structure and strong interaction between Ti3C2Tx MXene and CuS. Meanwhile, the inherent restacking of Ti3C2Tx MXene nanosheet and serious agglomeration of CuS can also be effectively avoided in the formation of aerogel. Those structural advantages originating from this novel gelation process favorably contributes to satisfactory Hg0 mass transfer and sufficient utilization of CuS active ligands, which largely strengthens Hg0 removal performance and broadens the fix-bed application of mineral sulfides. Consequently, the Hg0 capture capacity and adsorption rate of CuS/Ti3C2Tx MXene aerogel reached 90596.4 g m−3 and 120.64 g m−3 min−1, respectively, far outbalancing those of the reported in-situ selenized copper foam with excellent Hg0 removal activity. The impressive Hg0 sequestration performance is attributed to its relatively large specific surface area, layered pore channel, and highly dispersed CuS particles, largely boosting Hg0 mass transfer and following sequestration. Moreover, other mineral sulfides/Ti3C2Tx MXene aerogels can also be constructed by just replacing divalent metal cations, which makes the initial effort towards the fix-bed utilization of mineral sulfides-based aerogel for vapor-phase Hg0 immobilization.

Solar-driven MXene aerogels with high water vapor harvesting capacity for atmospheric water harvesting

Solar-driven MXene aerogels with high water vapor harvesting capacity for atmospheric water harvesting

Multi-functional and multi-scenario applications for MXene aerogels with synergistically enhanced asymmetric modules

Multi-functional and multi-scenario applications for MXene aerogels with synergistically enhanced asymmetric modules