Synthesis and Characterization of 2D Molybdenum Carbide (MXene)

Abstract

Large scale synthesis and delamination of 2D Mo 2 CT x (where T is a surface termination group) has been achieved by selectively etching gallium from the recently discovered nanolaminated, ternary transition metal carbide Mo 2 Ga 2 C. Different synthesis and delamination routes result in different fl ake morphologies. The resistivity of free-standing Mo 2 CT x fi lms increases by an order of magnitude as the temperature is reduced from 300 to 10 K, suggesting semiconductor-like behavior of this MXene, in contrast to Ti 3 C 2 T x which exhibits metallic behavior. At 10 K, the magnetoresistance is positive. Additionally, changes in electronic transport are observed upon annealing of the fi lms. When 2 µm thick fi lms are tested as electrodes in supercapacitors, capacitances as high as 700 F cm −3 in a 1 M sulfuric acid electrolyte and high capacity retention for at least 10,000 cycles at 10 A g −1 are obtained.Free-standing Mo 2 CT x fi lms, with ≈8 wt% carbon nanotubes, perform well when tested as an electrode material for Li-ions, especially at high rates. At 20 and 131 C cycling rates, stable reversible capacities of 250 and 76 mAh g −1 , respectively, are achieved for over 1000 cycles.

High-Voltage Symmetric Supercapacitor Based on 2D Titanium Carbide (MXene, Ti2CTx)/Carbon Nanosphere Composites in a Neutral Aqueous Electrolyte

“…4m · E S R [9] where ESR ( ) is the equivalent series resistance of the system, determined from the initial voltage drop between the first two points at the beginning of the discharge curve. In the case where discharge comes immediately after charge by switching the current, it is determined by Equation 10.…”

“…2-D materials potentially have large electroactive surfaces and therefore attract research attention. MXenes are currently studied, both theoretically and experimentally, as potential electrode materials for energy storage devices such as batteries [6][7][8][9][10][11][12][13][14][15][16] and ECs 9,14,17-32 as well as other uses. …”

“…2-D materials potentially have large electroactive surfaces and therefore attract research attention. MXenes are currently studied, both theoretically and experimentally, as potential electrode materials for energy storage devices such as batteries [6][7][8][9][10][11][12][13][14][15][16] and ECs 9,14,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] as well as other uses. 33,34 Although the MXene materials do not possess such a high surface area as electric double-layer capacitor (EDLC) materials, 6,11,24,35,36 they are suggested to employ the energy storage through pseudocapacitive ion intercalation route giving rise to high capacitance and attractive electrochemical properties without the need for a high surface area.…”

Atomic H-Induced Mo2C Hybrid as an Active and Stable Bifunctional Electrocatalyst

“…25 Furthermore, hot-filament chemical vapor deposition (HF-CVD) is one of the most promising techniques for 4 growing high melt point carbide materials at relatively low substrate temperature, such as WC, 26 M 3 C (M:Fe,Co,Ni), 27 silicon carbide (SiC) 28 and so on. In the HF-CVD processing, the filament was heated to over 2000 o C for activation of the source gas.…”

Rendering Ti3C2Tx (MXene) monolayers visible

“…The MAX phases, in turn, are a large ( > 70) family of layered ternary transition metal carbides, where M is an early transition metal, A is an A-group element (mostly groups 13 and 14), and X is C or/and N [16]. Because during etching, the A-group element layers such as Al and Ga are replaced by -O, -OH, and -F terminations [17,18], the proper designation of the resulting 2D material is Figure 1. (a) AFM scan of a Ti 3 C 2 T x monolayer on a 285 nm thick SiO 2 substrate.…”