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