Anisotropic MXene Aerogels with a Mechanically Tunable Ratio of Electromagnetic Wave Reflection to Absorption

Abstract

Fast progress of wireless communication techniques and applications, and the trend toward miniaturization and portability of wireless electronic devices lead to increasingly complex electromagnetic (EM) environments. Flexible, lightweight, and efficient electromagnetic interference shielding materials, which can be used in different frequency ranges, are needed for protection against EM pollution. [1,2] In general, electromagnetic interference (EMI) shielding materials refer to both EM wave reflection and absorption, as incident EM wave on a material surface undergoes reflection, absorption, and transmission. Although conventional EMI shielding materials, such as metals and graphite, possess high EMI shielding ability, it is mainly dominated by reflection. [3] The control of the ratio of EM reflection to absorption for EMI shielding materials is still a tremendous challenge.Macroporous structures offer an effective route to enhance EM wave absorption capability, owing to inner multiple scattering and EM field-induced currents that occur on walls and/or struts of pores. Porous metal and carbon-based foams made of Ag nanowires, graphene, and carbon nanotubes have been developed for EMI shielding. [4] Metal foams with high electrical conductivity have excellent EMI shielding effectiveness. However, the high density and easy surface oxidation, which changes the electrical conductivity, limit their practical applications. Additionally, plastic deformation of metals limits their lifetime in flexible electronic devices. Recently, graphenebased porous structures have emerged as promising candidates for EM wave suppression. This potential is attributed to the low density, large specific surface area, high carrier mobility, adjustable pore size, and improved flexibility of graphene foams. [5] However, pure graphene foam architecture that contributes to high-performance EMI shielding capability can only be produced via expensive chemical vapor deposition on a metal template. [6] As an alternative, reduced graphene oxide-based foams have been made using freeze-drying, solvothermal, and template methods. [7,8] Still, the low electrical conductivity and permittivity of reduced graphene oxide drastically decreases EMI shielding effectiveness and increases the material thickness required to achieve adequate protection.Lightweight and mechanically flexible materials that can provide efficient electromagnetic interference (EMI) shielding are highly desirable for protecting portable and smart electronic devices against electromagnetic pollution. Here, the authors report a tunable design of a three-dimensional (3D) porous aerogel structure made of 2D transition metal carbides and a carbonitride (MXene) with a long-range order of aligned lamellar architecture for EMI shielding. Bidirectional freeze-casting of MXene colloidal solutions is used to fabricate robust, compressible and lightweight aerogels, and achieve orientational assembly leading to outstanding EMI shielding performance and tunable ratio of reflection to absorption...

An effective utilization of MXene and its effect on electromagnetic interference shielding: flexible, free-standing and thermally conductive composite from MXene–PAT–poly(p-aminophenol)–polyaniline co-polymer

“…Hence, addition of PAT composition, arrangement of MXene ake in composite and presence of hydroxyl functional group in polymer signicantly increase tensile strength of the composites. 11,96,97 The SSE range is (28.85-40.49) dB g À1 cm 3 , in which uMXPAT demonstrates the lowest value of 28.85 dB g À1 cm 3 . The SSE/t range was 236.45-721.25 dB g À1 cm 2 in which uMX-PAT possessed maximum value of 721.25 dB g À1 cm 2 (Table S7 †).…”

MXene-based 3D porous macrostructures for electrochemical energy storage

“…Despite the increasing number of promising papers being published [58,[68][69][70][71][72], to date, freeze-casting of 2D materials still lacks a dedicated review or progress report to compile, compare, critically analyze and identify the specific challenges the technique presents when applied to different 2D materials.…”

“…Using a bidirectional freeze-casting technique, Han et al reported additive-free, aligned, lamellar and macroporous MXene (Ti 3 C 2 T x , Ti 2 CT x and Ti 3 CNT x ) aerogels for electromagnetic shielding [70]. The bidirectional growth of ice crystals arranges MXene flakes into a long range alignment of the lamellar architecture (figure 8).…”

Electrochemical Behavior of Ti3C2Tx MXene in Environmentally Friendly Methanesulfonic Acid Electrolyte

“…[1] MXenes are usually synthesized by chemical etching and exfoliation of ternary ceramics of general formula M n + 1 AX n ,w ith Ar epresenting Al, Si, or Ga. [1a, 2] To date, more than thirty different chemical compositions of MXenes have been experimentally obtained, andm any more have been theoretically predicted.M Xenes, in particularT i 3 C 2 T x ,t he first discovereda nd most investigated MXene, have been studied for energys torage, [3] sensors, [4] adsorption materials, [5] catalysis, [6] electromagnetic interferences hielding, [7] solar cells, [8] and medical applications. One of the larger families of 2D materials is the transition metal carbides, carbonitrides, and nitrides called MXenes, with ag eneral formula M n + 1 X n T x ,w here Mr epresents early transition metals (i.e.,S c, Ti,V ,C r, Zr,H f, Nb, Mo, Ta ,a nd W), Xi sc arbon and/or nitrogen, T x stands for the surfacet erminations (hydroxy,o xygen or fluorine), and n = 1, 2, or 3.…”

“…One of the larger families of 2D materials is the transition metal carbides, carbonitrides, and nitrides called MXenes, with ag eneral formula M n + 1 X n T x ,w here Mr epresents early transition metals (i.e.,S c, Ti,V ,C r, Zr,H f, Nb, Mo, Ta ,a nd W), Xi sc arbon and/or nitrogen, T x stands for the surfacet erminations (hydroxy,o xygen or fluorine), and n = 1, 2, or 3. [1] MXenes are usually synthesized by chemical etching and exfoliation of ternary ceramics of general formula M n + 1 AX n ,w ith Ar epresenting Al, Si, or Ga. [1a, 2] To date, more than thirty different chemical compositions of MXenes have been experimentally obtained, andm any more have been theoretically predicted.M Xenes, in particularT i 3 C 2 T x ,t he first discovereda nd most investigated MXene, have been studied for energys torage, [3] sensors, [4] adsorption materials, [5] catalysis, [6] electromagnetic interferences hielding, [7] solar cells, [8] and medical applications. [9] Improving supercapacitors is one of the key energy storage challenges, as they are complementary to batteries and important in renewable energy production,a sw ell as many other technologies.…”