Unidirectional Freeze Casting Research Articles

High-aligned oppositely-charged nanocellulose/MXene aerogel membranes through synergy of directional freeze-casting and structural densification for osmotic-energy harvesting

Optimization of ion-transport paths can considerably improve ion-transport capabilities in charged nanochannels. Thus, the assembly of high-charge-density one- and two-dimensional nanomaterials into aligned nanochannels is necessary for high-performance osmotic-energy harvesting. Herein, we prepared cellulose/MXene aerogel membranes with opposite charges and aligned nanochannels via chemical modification on algal cellulose nanofibers and MXene nanosheets, unidirectional freeze casting, and structural densification to considerably enhance the ionic conductivity in low-concentration solutions (maximum conductivity of 2.88 × 10−3 S cm−1). In particular, the aligned membrane had an output power density of 2.97 and 4.89 times higher than membranes used for suction filtration and isotropic nanochannels, respectively, demonstrating the necessity for nanostructure control. In addition, due to the photothermal effect of MXene, the positively–negatively (P–N) charged unit produced a maximum output power density of 8.87 W m−2 under a concentration gradient of artificial seawater and river water and simulated sunlight. Moreover, the unit maintained 90.4% of its original output capacity after 168 h of operation. As a proof of concept, we created nine series of P–N units and successfully powered an electronic calculator with an output voltage of 1.85 V. This study reveals improvements in developing renewable materials with an aligned nanostructure for high-performance osmotic-energy conversion.

Low–temperature superelastic, anisotropic, silane-crosslinked sodium alginate aerogel for thermal insulation

Bio-aerogels have attracted much attention owing to their remarkable properties, but their brittle and poor elasticity has limited their further applications. Here, we propose a strategy of in-situ silanization crosslinking combined with unidirectional freeze casting (SUFC) to prepare superelastic sodium alginate (SA) aerogels. The resulting aerogel was ultra-light (0.048 g/cm3), high porosity (96.86 %), and self-extinguishing from fire. Aerogels exhibited anisotropic properties, such as low-temperature elasticity (500 g compression at −70 °C 10-cycle, 99.6 % recovery), exceptional fatigue resistance (100-cycle at 50 % strain), and excellent thermal insulation (0.0696 W·m−1·K−1). Thus, the SUFC strategy provides considerable freedom for constructing multi-material, lamellar/honeycomb structured alginate-based aerogels, which pave the way to thermal insulation development at low temperatures.

Fabrication and characterization of glycerin-plasticized soy protein amyloid fibril scaffolds by unidirectional freeze casting method

Soy protein amyloid fibrils (SAFs) plasticized with glycerin were prepared into aligned porous scaffolds through the unidirectional freeze casting method. The impact of the amount of glycerin on the structural and functional properties of the SAFs-Gly scaffolds was investigated. Scanning electron microscopy confirmed that the aligned pore size and distribution of the scaffolds, with diameters ranging of 10–50 μm, could be adjusted by varying the amount of glycerin. Increasing the glycerin content decreased the median pore size of the scaffolds and increased the strain at the yield point by up to 40%. Additionally, the water resistance of the scaffolds significantly increased without any obvious changes in morphology. Differential scanning calorimetry analysis revealed two glass transitions in the SAFs/glycerin systems, corresponding to the glycerin-rich and protein-rich domains, respectively. FTIR spectroscopy indicated the formation of hydroxyl interactions and intermolecular hydrogen bonding between SAFs and glycerin. X-ray diffraction and small-angle X-ray scattering suggested that glycerin can induce SAFs crystallization, structural separation, and exfoliation of β-sheets to some extent. These results demonstrate the prospective application of this approach in the preparation of food-based polymer scaffolds and its usefulness in the food industry.

Carbonization welding graphene architecture for thermally conductive phase change composites with solar/electric-to-heat conversion ability

Graphene-based porous architectures are promising in addressing the poor thermal conductivity, leakage, shape stability problems of organic phase change materials (PCMs), meanwhile endowing them with excellent solar/electric-to-heat conversion ability, but they are still limited by the high interfacial thermal/electrical resistance in architectures caused by organic “binders”. In this work, in view of the excellent gel ability of aramid nanofibers (ANF) and its highly ordered conjugate molecular structure, a promising graphene porous architecture assisted by ANF was constructed by unidirectional freeze casting coupled with carbonization welding technique. Due to the similar graphite lattice structure of ANF-derived carbonization and graphene, the interfacial thermal/electrical resistance in highly vertically oriented graphene architecture was greatly reduced. As a result, the PCMs composite encapsulated by the graphene architecture carbonizing at 1500 °C exhibited an outstanding thermal conductivity of as high as 4.85 W/mK at only 4.26 vol%, which enables a rapid heat transfer and storage in PCM composite. The honeycomb porous graphene architecture with high porosity can accommodate sufficient PCMs for energy storage, showing a high latent heat enthalpy of 149.7 J/g with excellent shape stability during phase change process. More importantly, the graphene architecture endows PCM composites with excellent solar/electric-to-thermal conversion capacities, which not only expands the types of energy stored by PCMs, but is also promising in the thermal management application requiring a continuous and stable temperature environment.

Embedding aligned nanofibrous architectures within 3D-printed polycaprolactone scaffolds for directed cellular infiltration and tissue regeneration

Three-dimensional (3D) printing provides a promising way to fabricate biodegradable scaffolds with designer architectures for the regeneration of various tissues. However, the existing 3D-printed scaffolds commonly suffer from weak cell-scaffold interactions and insufficient cell organizations due to the limited resolution of the 3D-printed features. Here, composite scaffolds with mechanically-robust frameworks and aligned nanofibrous architectures are presented and hybrid manufactured by combining techniques of 3D printing, electrospinning, and unidirectional freeze-casting. It was found that the composite scaffolds provided volume-stable environments and enabled directed cellular infiltration for tissue regeneration. In particular, the nanofibrous architectures with aligned micropores served as artificial extracellular matrix materials and improved the attachment, proliferation, and infiltration of cells. The proposed scaffolds can also support the adipogenic maturation of adipose-derived stem cells (ADSCs) in vitro. Moreover, the composite scaffolds were found to guide directed tissue infiltration and promote nearby neovascularization when implanted into a subcutaneous model of rats, and the addition of ADSCs further enhanced their adipogenic potential. The presented hybrid manufacturing strategy might provide a promising way to produce additional topological cues within 3D-printed scaffolds for better tissue regeneration.

Multi-directional freeze casting of porous ceramics with bone-inspired microstructure

Porous ceramics are favored in a multitude of applications, such as filters, catalyst supports, and tissue engineering scaffolds. However, conventional fabrication techniques find it particularly challenging to preserve sufficient mechanical strength in highly porous ceramics. Although unidirectional freeze casting can fabricate porous ceramics with high strength vertically, the strength in other directions is inadequate due to a lack of lateral structural control. Herein, inspired by the cancellous bone, we propose a novel multi-directional freeze casting technique to prepare highly mechanically efficient porous ceramics. A multi-directional temperature field is ingeniously designed to mimic the stress-responsive growth pattern of the cancellous bone. To further the lateral structural control, ceramic fibers are incorporated to form mineral bridging. In this process, alumina-mullite composite ceramics are prepared with hierarchical structures, including micro-level multi-oriented struts, sub-micro-level interlamellar bridges and nano-level eutectic phases. They endow the ceramics with high porosity (∼75%) and high strength in all 3D spatial directions (8.4–20.1 MPa), while effectively preventing the catastrophic brittle failure. Therefore, the mechanically enhanced porous ceramics demonstrate the remarkable controllability of multi-directional freeze casting in hierarchical structures. Also, our work opens up a new horizon for fabricating highly mechanically efficient porous materials, including hierarchically structured biomimetic ceramics.

Lamellar and interpenetrated Al/(Al2O3–TiC) composites prepared by bidirectional freeze casting and melt infiltration

Unidirectional freeze casting followed by sintering and infiltration treatments has been proved to be a promising method to produce lamellar composites with good strength and toughness. However, it remains a great challenge to tailor the microstructure, particularly the lamellar orientation at the centimeter scale and the architectural features over multiple scales. Herein, we prepared Al/(Al2O3–TiC) composites with a long-range ordered lamellar architecture via bidirectional freeze-casting and melt-infiltration techniques. The incorporation of a certain amount of TiC (∼3 μm in diameter) into the Al2O3 slurry increased the solidification velocity and decreased the ceramic layer thickness. Furthermore, it greatly facilitated the infiltration of liquid Al into the interlamellar channels and in-layer cavities, thus improving the mechanical properties of the composites. The maximum flexural strength (474 ± 8 MPa) and crack-growth toughness (42.7 ± 2.7 MPa m1/2) appeared in the composite containing ∼27 vol% ceramics with Al2O3:TiC = 5:5. Moreover, the composites exhibited anisotropic mechanical properties. The flexural strength loaded in the direction parallel to the ceramic layers was higher than that perpendicular to them, while the toughness exhibited an opposite trend. The main toughening mechanisms included crack blunting, crack deflection, plastic deformation of the metal layers and multiple cracking. This work offers a cost-effective and scalable method for the fabrication of laminated composites with exceptional damage tolerance.

Anisotropic electromagnetic absorption of the aligned Ti3C2Tx MXene/RGO nanocomposite foam

Transition metal carbides/nitrides (MXenes) with superb electrical properties have excellent applications for electromagnetic wave absorption (EMA). Whereas, the three-dimensional (3D) MXene's fabrication assemblies with anisotropic EMA performance are still a challenge as MXene nanosheets have weak gelation capabilities. In this study, graphene oxide was introduced to assist in fabricating the 3D MXene/RGO porous foam through the method of unidirectional freeze casting followed by hydrazine hydrate chemical reduction. Combined with the excellent electrical properties of MXene and RGO, the resultant lightweight (∼6 mg/cm3) MXene/RGO composite foam (MGF) with a free-standing configuration exhibits anisotropic microwave absorption performance. At the sample thickness of 5 mm, MGF-1/2 shows −26.79 dB minimum reflection loss at 4.39 GHz along the perpendicular direction that relates to the unidirectional freeze casting direction. While along the parallel direction, materials with 3 mm thickness reach the maximum effective bandwidth of 8.34 GHz. The lightweight MXene/RGO nanocomposite foam with anisotropic performance may significantly extend the feasibility of MXenes in EMA.

Dynamically Tunable All-Weather Daytime Cellulose Aerogel Radiative Supercooler for Energy-Saving Building.

A passive cooling strategy without any electricity input has shown a significant impact on overall energy consumption globally. However, designing tunable daytime radiative cooler to meet requirement of different weather conditions is still a big challenge, especially in hot, humid regions. Here, a novel type of tunable, thermally insulating and compressible cellulose nanocrystal (CNC) aerogel coolers is prepared via chemical cross-linking and unidirectional freeze casting process. Such aerogel coolers can achieve a subambient temperature drop of 9.2 °C under direct sunlight and promisingly reached the reduction of ∼7.4 °C even in hot, moist, and fickle extreme surroundings. The tunable cooling performance can be realized via controlling the compression ratio of shape-malleable aerogel coolers. Furthermore, energy consumption modeling of using such aerogel coolers in buildings in China shows 35.4% reduction of cooling energy. This work can pave the way toward designing high-performance, thermal-regulating materials for energy consumption savings.

Ultralight biomass-based carbon aerogel with hierarchical pore structure fabricated using unidirectional freeze casting and potassium hydroxide activation

A low-cost biomass carbon aerogel with a hierarchical pore structure (BCA-H) was prepared from straw using unidirectional freeze casting and potassium hydroxide (KOH) activation. The morphology, microstructure, and properties of the material were investigated. The hierarchical pore structure is a three-dimensional structure consisting of micropores, mesopores, and macropores. The material exhibits an ultra-low density (0.038 g/cm3), as well as a high porosity (98.2 %) and specific surface area (1531 m2/g). After hydrophobic modification, the contact angle of the sample with water was 169.5°, and its adsorption capacities for acetone and rapeseed oil were 29 and 33 times its mass, respectively. The material has promising prospects in adsorption technology, such as for organic solvent adsorption and oil–water separation.

3D Printed MXene Aerogels with Truly 3D Macrostructure and Highly Engineered Microstructure for Enhanced Electrical and Electrochemical Performance.

Assembling 2D materials such as MXenes into functional 3D aerogels using 3D printing technologies gains attention due to simplicity of fabrication, customized geometry and physical properties, and improved performance. Also, the establishment of straightforward electrode fabrication methods with the aim to hinder the restack and/or aggregation of electrode materials, which limits the performance of the electrode, is of great significant. In this study, unidirectional freeze casting and inkjet-based 3D printing are combined to fabricate macroscopic porous aerogels with vertically aligned Ti3 C2 Tx sheets. The fabrication method is developed to easily control the aerogel microstructure and alignment of the MXene sheets. The aerogels show excellent electromechanical performance so that they can withstand almost 50% compression before recovering to the original shape and maintain their electrical conductivities during continuous compression cycles. To enhance the electrochemical performance, an inkjet-printed MXene current collector layer is added with horizontally aligned MXene sheets. This combines the superior electrical conductivity of the current collector layer with the improved ionic diffusion provided by the porous electrode. The cells fabricated with horizontal MXene sheets alignment as current collector with subsequent vertical MXene sheets alignment layers show the best electrochemical performance with thickness-independent capacitive behavior.

Thermal insulating, light-weight and conductive cellulose/aramid nanofibers composite aerogel for pressure sensing

Conductive nanocellulose aerogels have attracted significant attention in pressure sensing for wearable devices owing to lightweight, sustainability and good chemical stability. Limited by its flammability and weak mechanical properties, aramid nanofiber (ANF) was designed as reinforcement to overcome the shortcoming mentioned above. Herein, the unidirectional freeze casting method was proposed to fabricate nanocellulose/aramid nanofiber (CA) aerogel. Then, the CA/PPy (CAP) aerogel was obtained by using the oriented structure of CA aerogel as a template for inducing conductive polypyrrole (PPy) in-situ formation inside the composite aerogel. The conductive aerogel with the ordered microstructure exhibited the anisotropic mechanical properties and thermal conductivity. And it could withstand high temperature without any destruction phenomenon. Moreover, the aerogel sensor revealed high strain sensitivity and satisfactory electrochemical performance. Lightweight CAP aerogel with controllable alignment, sensitive sensing property and thermal stability is very promising in pressure sensor under some extreme conditions.

Biomimetic 3D aligned conductive tubular cryogel scaffolds with mechanical anisotropy for 3D cell alignment, differentiation and in vivo skeletal muscle regeneration

Developing 3D conductive aligned cryogels has great potential for skeletal muscle trauma treatment because they can mimic anisotropic structure, conductivity, and recoverable cyclic compression of the microenvironment of native skeletal muscle. In this work, a series of cryogels possessing 3D aligned morphology, conductivity, and excellent anisotropic mechanical compression property based on gelatin (GT) and polydopamine coated carbon nanotubes (PCNTs) were fabricated as skeletal muscle tissue scaffolds by using unidirectional freeze casting technology. The aligned microstructure of cryogels depended on gelatin concentration, and GT7.5 (with the gelatin content of 7.5% w/v) showed excellent aligned structure. Interestingly, the mechanical property of the aligned cryogels was similar to that of native skeletal muscle in terms of the dynamic contraction behavior and the anisotropic compression property due to the internal anisotropy structure. The aligned cryogel GT7.5 with good biocompatibility significantly promoted the alignment and elongation of C2C12 myoblasts. Moreover, the introduction of PCNTs enhanced the mechanical properties of cryogel GT7.5 and had a positive effect on myogenic differentiation of C2C12 cells. The aligned conductive GT7.5C2 cryogel significantly promoted new born muscle tissue generation compared to non-aligned group (GT7.5C2N) and non-conductive group (GT7.5) in a rat tibialis anterior muscle defect model. These data suggested that the 3D aligned conductive cryogel with conductivity and anisotropic compression property is a promising scaffold candidate for skeletal muscle tissue engineering.

Porous Ti6Al4V alloys with high strength-to-modulus ratio fabricated by unidirectional freeze casting of SiC fiber-containing slurry

Porous titanium alloys with high strength-to-modulus ratio are one of the promising materials for bone implants. In the present work, porous Ti6Al4V alloys with SiC fiber bridges and fiber reinforced wall structure were obtained by unidirectional freeze casting of SiC fiber-containing slurry. The effect of SiC fiber content on the pore structure, microstructure, interface and compressive properties was systematically investigated. The formations of fiber bridges and fiber reinforced wall structure were elaborated through analyzing the interaction between fibers and ice front. Addition of SiC fibers has significant effects on the porosity, structural wavelength, and pore morphology of porous alloys. Porosity increases with the increase in fiber content, and pore morphology changes from lamellar to dendritic. Porous Ti6Al4V alloys mainly contain equiaxed α and β phase. Crystalline phases of Ti5Si3 and TiC are present at the interface. Micropores are also observed on the fiber side close to the interface due to the Kirkendall effect. Both Young's modulus and yield stress increase with the increase in SiC fiber content, while they dramatically decrease at higher fiber content of 10 vol%. SiC fiber bridges and fiber reinforced wall structure have synergetic strengthening effects for suppressing buckling deformation of lamellar walls and thus for improving the strength of porous titanium alloys. Porous Ti6Al4V alloys fabricated by 2 vol% SiC fibers possess high porosity of 67% and high strength-to-modulus ratio of 0.027.

Ice-templated hybrid graphene oxide—graphene nanoplatelet lamellar architectures: tuning mechanical and electrical properties

The traditional freeze-casting route for processing graphene-based aerogels is generally restricted to aqueously dispersed flakes of graphene oxide (GO) and post-processing reduction treatments, which brings restrictions to the aerogels electrical properties. In this work, we report a versatile aqueous processing route that uses the ability of GO todisperse graphene nanoplatelets (GNP) to produce rGO-GNP lamellar aerogels via unidirectional freeze-casting. In order to optimise the properties of the aerogel, GO-GNP dispersions were partially reduced by L-ascorbic acid prior to freeze-casting to tune the carbon and oxygen (C/O) ratio. The aerogels were then heat treated after casting to fully reduce the GO. The chemical reduction time was found to control the microstructure of the resulting aeorgels and thus to tune their electrical and mechanical properties. An rGO-GNP lamellar aerogel with density of 20.8 ± 0.8 mg cm−3 reducing using a reduction of 60 min achieved an electrical conductivity of 42.3 S m−1. On the other hand, an optimal reduction time of 35 min led to an aerogel with compressive modulus of 0.51 ±0.06 MPa at a density of 23.2 ± 0.7 mg cm−3, revealing a compromise between the tuning of electrical and mechanical properties. We show the present processing route can also be easily applied to produce lamellar aerogels on other graphene-based materials such as electrochemically exfoliated graphene.

Conductive and highly compressible MXene aerogels with ordered microstructures as high-capacity electrodes for Li-ion capacitors

Assembling two-dimensional (2D) materials into functional three-dimensional (3D) structures can enable their use in a wide variety of applications. For energy storage devices, 3D electrodes with high ionic and electronic transport properties and decent mechanical properties are expected to prompt the fabrication of the next generations of devices with high energy and power densities. Herein, we report a simple, efficient, and scalable process based on unidirectional freeze casting to fabricate ordered and porous 3D aerogels from 2D Ti3C2Tx MXene flakes. The fabricated aerogels show excellent mechanical, electrical, and electrochemical properties. Our studies show that the processing conditions significantly affect the properties of MXene aerogels. The electrical conductivity and mechanical properties of fabricated aerogels directly correlate with their structural features. The mechanical test results showed that MXene aerogels with ordered structures could withstand almost 50% of strain before recovering to their original shape and maintain their electrical conductivities during continuous compressive cycling. As electrode materials for lithium-ion capacitors, the fabricated aerogels delivered a significantly high specific capacity (~1210 mAh/g at 0.05 A/g), excellent rate capability (~200 mAh/g at 10 A/g), and outstanding cycling performance. We believe that the MXene aerogels with ordered structures have promising properties for a broad range of applications, including energy storage devices and strain sensors.

Wet-resilient graphene aerogel for thermal conductivity enhancement in polymer nanocomposites

Three-dimensional (3D) graphene-based aerogels have significant potential for adsorption, sensors, and thermal management applications. However, their practical applications are limited by their disorganized structure and ultra-low resilience after compression. Some methods can realize a well-aligned structure, however, they involve high costs and complex technology. Herein, a 3D graphene hybrid aerogel with an anisotropic open-cell and well-oriented structure is realized by unidirectional freeze casting, which combines the ‘soft’ (e.g. graphene oxide, Tween-80) and ‘hard’ (e.g. graphene assembly) components to realize full recovery after flattening. A graphene aerogel annealed at a moderate temperature (∼200 °C) can possess superhydrophilicity and outstanding wet-resilience properties, including after being pressed under 40 MPa. Furthermore, the graphene aerogel annealed at a high temperature of ∼1500 °C exhibits excellent thermal conductivity enhancement efficiency in polydimethylsiloxane (PDMS). The resultant nanocomposites clearly demonstrate anisotropic thermal conductivity and promising applications as thermal interface materials. This strategy offers new insights into the design and fabrication of 3D multifunctional graphene aerogels.

In-situ X-Ray observations and thermal modeling of unidirectional and bidirectional freeze casting

Freeze casting is a cost effective, efficient, and versatile technique capable of producing 3D structures with controlled pore shapes, orientation of crystals, and components' geometries in many porous materials. Freeze casting of hydroxyapatite (HAP) has been widely applied to bone tissue engineering due to HAP's biodegradable, biocompatible, and osteoconductive properties. It provides interconnected porous structures with a relatively high mechanical strength. However, there are still many unexplained phenomena and features because of the complexity of the process. This study demonstrates the use of X-ray synchrotron micro-radiography for providing time-resolved, in-situ imaging of ice crystal growth in the HAP suspensions. The experimental results show the ice crystal growth behavior under unidirectional and bidirectional freeze casting conditions. The finite element modeling (FEM) of the freeze casting process has been used to predict the development of ice front position and temperature gradient in the suspensions during the freeze casting.

Bioinspired Manufacturing of Aerogels with Precisely Manipulated Surface Microstructure through Controlled Local Temperature Gradients.

The freeze casting process has been widely used for fabricating aerogels due to its versatile and environmentally friendly nature. This process offers a variety of tools to tailor the entire micropore morphology of the final product in a monolithic fashion through manipulation of the freezing kinetics and precursor suspension chemistry. However, aerogels with nonmonolithic micropore morphologies, having pores of various sizes located in certain regions of the aerogels, are highly desired by certain applications such as controlled drug-delivery, bone tissue engineering, extracellular simulation, selective liquid sorption, immobilized catalysts, and separators. Furthermore, aerogels composed of micropores with predesigned size, shape, and location can open up a new paradigm in aerogel design and lead to new applications. In this study, a general manufacturing approach is developed to control the size, shape, and location of the pores on the aerogel surface by applying a precise control on the local thermal conductivity of the substrate used in a unidirectional freeze casting process. With our method, we created patterned low and high thermal conductivity regions on the substrate by depositing patterned photoresist polymer features. The photoresist polymer has a much lower thermal conductivity, which resulted in lower cooling/freezing rates compared to the silicon substrate. Patterned thermal conductivity created a designed temperature profile yielding to local regions with faster and slower freezing rates. Essentially, we fabricated aerogels whose micropore morphology on their surface was a replica of the patterned substrates in terms of size and location of the micropores. Using the same substrates, we further showed the possibility of 3D printed aerogels with precisely controlled, surface micropore morphologies. To the best of our knowledge, this is the first study that reports aerogels having micropore morphologies (e.g., size, shape, and location) that are precisely controlled through locally controlled thermal conductivity of the substrates.

Anisotropic Electromagnetic Absorption of Aligned Ti3C2Tx MXene/Gelatin Nanocomposite Aerogels.

Assembling Ti3C2Tx MXene nanosheets into three-dimensional (3D) architecture with controllable alignment is of great importance for electromagnetic wave absorption (EMA) application. However, it is a great challenge to realize it due to the weak van der Waals interconnection between MXene nanosheets. Herein, we propose to introduce gelatin molecules as a "chemical glue" to fabricate the 3D Mxene@gelatin (M@G) nanocomposite aerogel using a unidirectional freeze casting method. The Ti3C2Tx MXene nanosheets are well aligned in the M@G nanocomposite aerogel, yielding much enhanced yet anisotropic mechanical properties. Due to the unidirectional aligned microstructure, the M@G nanocomposite aerogel shows significantly anisotropic EMA properties. M@G-45 shows a -59.5 dB minimum reflection loss (RLmin) at 14.04 GHz together with a 6.24 GHz effective absorption bandwidth in the parallel direction (relative to the direction of unidirectional freeze casting). However, in the vertical direction of the same M@G aerogel, RLmin is shifted to a much lower frequency (4.08 GHz) and the effective absorption bandwidth decreases to 0.86 GHz. The anisotropic electromagnetic energy dissipation mechanism was deeply investigated, and the impendence match plays a critical role for electromagnetic wave penetration. Our lightweight M@G nanocomposite aerogel with controllable MXene alignment is very promising in EMA application.