2D Transition Metal Carbides (MXenes): Applications as an Electrically Conducting Material

Abstract

conductive nature, tunable surface chemistry, and the ability to intercalate other metal ions, MXenes are at the forefront of the research in this field. One of the major factors responsible for the rapid progress in the research on MXene materials is their electrical conductivity, which is the highest among all synthetic 2D materials, more than ten times the conductivity of reduced graphene oxide (rGO) films. [7,8] This unique characteristic coupled with a hydrophilic nature and a good dispersion stability has expanded the applications of MXenes in electromagnetic interference (EMI) shielding, [9] optoelectronics, [10] sensing, [11] thermal heaters (THs), [12] thermoelectrics, [13] high dielectric materials, [14] triboelectric nanogenerators, [15] and electrode materials for batteries and supercapacitors. [16,17] Compared to graphene, the flagship 2D material, MXenes offer greater promise in applications requiring high electrical conductivity and solution processing to construct thin films via low-cost techniques such as spray coating. MXenes can form stable dispersions in a variety of solvents without an additive or surfactant; these dispersions are stable for several days, making them ideal for designing optoelectronic, plasmonic, and polymer composite applications. Most recently, a large area MXene film with dimensions of 100 cm × 10 cm was reported to possess an outstanding tensile strength (≈570 MPa), excellent electrical conductivity (≈15 100 S cm −1) and superior EMI shielding effectiveness (SE), (≈50 dB for 940 nm thick film), surpassing all the existing 2D materials produced to date. [18] The search for new and intriguing applications based on the outstanding electrical conductivity of MXenes is a topic of great interest. [6,19] MXenes are typically synthesized by a top-down selective etching procedure of a parent MAX phase, where "M" is an early transition metal element, "A" represents an element from Group 13 or 14, and "X" is either carbon or nitrogen. [20] To date, more than 100 pure MAX phase materials have been prepared; this number increases with the addition of solid solutions and/ or ordered double transition metal structures. [21] Potentially, all the MAX phase precursors can be converted to their respective MXenes, presenting numerous possibilities of materials design, in particular, regulating the electronic transport in a 2D lattice. [6] The "A" group elements in the MAX phase are etched using a mixture of acids and salts, including hydrofluoric acid (HF), NH 4 F, NaF, CaF, HCl+LiF mixture (forming in situ HF), HF+HCl, and others. [20,22] The etching process leaves the termination groups, T x (e.g., O, OH, and F) on the surface of MXenes, which are bonded to the outer M layers. The surface chemistry of MXenes offers significant opportunities to develop Since their discovery in 2011, 2D transition metal carbides, nitrides, and carbonitrides, known as MXenes, have attracted considerable global research interest owing to their outstanding electrical conductivity coupled with light weight, ...

Flexible and Waterproof 2D/1D/0D Construction of MXene-Based Nanocomposites for Electromagnetic Wave Absorption, EMI Shielding, and Photothermal Conversion

“…Generally, the high electrical conductivity of the material is a prominent factor in achieving an excellent EMI shielding performance [101][102][103]. Here, the EMI shielding efficiency of Ti 3 C 2 T x /CNTs/Co nanocomposites was investigated in depth, considering the remarkable conductivity of the 2D Ti 3 C 2 T x and 1D CNTs in the composites.…”

Hydrophilicity and Hydrophobicity Control of Plasma‐Treated Surfaces via Fractal Parameters

“…Complex nanomaterials and nanocomposites based on hierarchical surface structures are currently under extensive investigation. This is because such materials can be applied in a very broad range of contexts, [1][2][3] from sensors, [4][5][6] photocatalysts, [7] bio-electronic interface devices, [8] water repelling and self-cleaning materials, [9] various nanoelectronics devices [10,11] to even space technology applications such as photon-active diamond films for space propulsion [12,13] and nanostructured emitters for plasma propulsion systems [14,15] that are critical for miniaturized space assets. [16,17] It is not uncommon for the nanocomposites of this type to feature very complex surface, internal and interfacial structures that may in some instances form a fractal-like morphology.…”

Flexible MXene‐Based Composites for Wearable Devices

“…Among these, resistance-type sensors exhibit the advantages of low fabrication cost and easily usable signal collection ability, and capacitance-type sensors have good linearity and low hysteresis, which make them attract more research interest. [5,22] Here, we mainly discuss the MXene-based flexible resistancetype and capacitance-type strain/pressure sensors. The flexible strain/pressure sensors can convert the force into resistance or capacitance signal output.…”