Exfoliation and Delamination of Ti₃C₂T_<i>x</i> MXene Prepared <i>via</i> 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_<i>x</i> <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-Ti₃C₂T_<i>x</i>. As a result, a self-supported Cl-terminated MXene film could be prepared by filtration. Finally, MS-Ti₃C₂T_<i>x</i> 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.