MXenes as Emerging 2D Materials for Anticorrosive Application: Challenges and Opportunities

Abstract

extraordinary optical, mechanical, and electronic properties. [1][2][3] MXenes (singular; MXene; pronounced "maxenes") are a class of 2D inorganic compounds that are composed of few-atom-thick layers of transition metal nitrides, carbides, or carbonitriles. [4] The first MXene, Ti 3 C 2 T x , was reported in 2011 by Naguib et al. without any prior prediction for the stability of such 2D materials. [5] MXenes (MXs) have a general chemical formula of M n+1 X n T x (n = 1-3) and are generally synthesized by the delamination of quaternary and tertiary 3D compounds called MAX phases. [6][7][8] In the chemical formula, M signifies a transition metal (e.g., Ti, Sc, Zr, Nb, etc.), X is C and/ or N, and T x is the oxygen, fluorine, or hydroxyl terminals consequent from the synthetic precursors (Figure 1). [9][10][11][12][13][14][15][16] MXenes can also be synthesized from other layered precursors such as Mo 2 Ga 2 C and Zr 3 Al 3 C 5 . After the establishment Ti 3 C 2 T x as of the first MXene, numerous MXenes have been synthesized and predicted theoretically. [17][18][19][20][21] Typically, MXenes are synthesized using a top-down approach that accounts for selective etching of A-layer from 3D crystalline-layered nitrides and carbides (MAX phases; Figure 2). [22] In MAX phases, M n+1 X n layers are held together by an atomic layer of an A-group transition element, usually group 13 or 16 group elements, principally Ga, Si, P, As, and Al. [23] The structures of three possible MAX phases are shown in Figure 2a. MAX phases themselves can be manufactured by the sintering of

Ti3C2Tx MXene-Polyaniline Nanocomposites for Redesigning Epoxy Coatings to Improve Anticorrosive Performance

“…), and X denotes nitrogen/carbon. The synthesis process governs the surface functionalities in M n +1 X n T x . , Moreover, these surface functionalities facilitate the covalent functionalization of MXene for improved stability and surface regulation from hydrophilicity to hydrophobicity . The Ti 3 C 2 T x MXene synthesized by Al etching from the Ti 3 AlC 2 MAX phase in an HF solution exhibits a high surface area, good electrical conductivity, and robust mechanical strength. , The impermeable nature, 2D planner structure, chemical stability, excellent mechanical strength, and high electric conductivity render MXenes attractive candidates for several applications, including protective coatings. , The surface functionalities of MXenes facilitate their dispersion in water, polar solvents, and polymeric matrices.…”

Superior Anticorrosion Performance of Well-Dispersed MXene-Polymer Composite Coatings Enabled by Covalent Modification and Ambient Electron-Beam Curing

“…34,35 Typically, MXene is a lamellar 2D material obtained by selective etching of A-layer atoms from the MAX phase with the general formula M n+1 X n T x , where M represents the transition metal element, X is carbon or nitrogen, and T is a functional group (e.g., −O, −OH, −F) introduced during the etching process. 36 The rich functional groups on the MXene surfaces allows versatile forms of modifications. Besides, the etched layers are linked by weak hydrogen bonds and van der Waals forces, which can be exfoliated into single/few-layer nanosheets in colloidal solutions.…”

“…As a result, they have been recently exploited to fabricate novel 2D material/polymer composite anticorrosion coatings. − In these composite coatings, 2D materials can form a labyrinth structure, and present a “nanobarrier” to greatly retard the corrosive species diffusion . Since its synthesis in 2011, the fast-growing 2D transition metal carbide/nitride, called MXene, has shown great promise in catalysis, supercapacitors, batteries, and other applications because of their ceramic/metallic advantages. , Typically, MXene is a lamellar 2D material obtained by selective etching of A-layer atoms from the MAX phase with the general formula M n +1 X n T x , where M represents the transition metal element, X is carbon or nitrogen, and T is a functional group (e.g., −O, −OH, −F) introduced during the etching process . The rich functional groups on the MXene surfaces allows versatile forms of modifications.…”

Recent Advancements of MXene/Nanocellulose‐Based Hydrogel and Aerogel: A Review

“…The schematics of three typical structures of MXenes are presented at the bottom. Reproduced with permission [276]. Copyright 2022, Wiley-VCH GmbH.…”