Exfoliation and Delamination of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene Prepared <i>via</i> Molten Salt Etching Route.

Liu, Liyuan; Orbay, Metin; Luo, Sha; Duluard, Sandrine; Shao, Hui; Harmel, Justine; Rozier, Patrick; Taberna, Pierre-Louis et al. · ACS Nano · 2022

basic_science · Level V

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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-Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> <i>via</i> 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-Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>. As a result, a self-supported Cl-terminated MXene film could be prepared by filtration. Finally, MS-Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> used as a Li-ion battery anode could achieve a high specific capacity of 225 mAh g<sup>-1</sup> at a 1C rate together with an excellent rate capability of 95 mAh g<sup>-1</sup> 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.