Exfoliation and Delamination of Ti₃C₂T_x MXene Prepared via Molten Salt Etching Route

Abstract

MXenes are two-dimensional metal carbides or nitrides that are currently proposed in many applications thanks to their unique attributes including high conductivity and accessible surface. Recently, a synthetic route was proposed to prepare MXenes from the molten salt etching of precursors allowing for the preparation of MXene (denoted as MS-MXenes, for molten salt MXene) with tuned surface termination groups, resulting in improved electrochemical properties. However, further delamination of as-prepared multilayer MS-MXenes still remains a major challenge. Here, we report on the successful exfoliation of MS-Ti3C2T x via the intercalation of the organic molecule TBAOH (tetrabutylammonium hydroxide), followed by sonication to separate the layers. The treatment time could be adapted to tune the wetting behavior of the MS-Ti3C2T x . As a result, a self-supported Cl-terminated MXene film could be prepared by filtration. Finally, MS-Ti3C2T x used as a Li-ion battery anode could achieve a high specific capacity of 225 mAh g–1 at a 1C rate together with an excellent rate capability of 95 mAh g–1 at 167C. These results also show that tuning of the surface chemistry of MXene is of key importance to this field with the likely result being increased electrochemical performance.

Electrically Conductive 2D Material Coatings for Flexible and Stretchable Electronics: A Comparative Review of Graphenes and MXenes

“…[58] Acidic solutions containing fluorides tend to be used as a chemical etchant, primarily hydrofluoric acid (HF) [56] . Alternative etching techniques include molten salt [59] , hydrothermal [60] , halogen [61] and electrochemical etching [62] .…”

“…[ 58 ] Acidic solutions containing fluorides tend to be used as chemical etchants, primarily hydrofluoric acid (HF). [ 56 ] Alternative etching techniques include molten salt, [ 59 ] hydrothermal, [ 60 ] halogen, [ 61 ] and electrochemical etching. [ 62 ] MXenes have yet to reach the ton per year scale of GNPs, with the current scale reaching 50 g batch reactors.…”

Microscopic Simulations of Electrochemical Double-Layer Capacitors

“…371 Many different compounds may be obtained by changing the synthesis method. Besides the change of composition, it is for example possible to tune the surface chemistry 372 by changing the surface elements, as shown in Figure 20. Nevertheless, simulations on such multicomponent compounds employed so far similar methods as the ones presented here for carbon materials.…”

Advances and emerging challenges in MXenes and their nanocomposites for biosensing applications

“…[53][54][55] Mixed acid reactions (HF + HCl), 53,56,57 etching in uoride salts (HCl + LiF, known as minimally intensive layer delamination (MILD) method), 58,59 water-free etching in polar solvents. 60 Some alternative methods such as uoride-free alkali etching, [61][62][63] halogens based etching 64,65 , and solid-state etching using molten salts, [66][67][68] have also been employed to produce MXenes but most of them are etched by using different solutions of HF acid. Usually, the MAX powder is immersed in HFcontained solutions during the etching process under continuous stirring, 69 while temperature, reaction time, and HF concentration are the key parameters.…”