Mild and Efficient Method for the In Situ Preparation of High-Quality MXene Materials Enabled by Hexafluoro Complex Anion Contained Salts Etching

Abstract

MXene is a promising two-dimensional (2D) material for energy storage applications owing to its exceptional conductivity and controllable surface chemistry. Currently, aqueous etching methods for the preparation of MXene sheets require a substantial quantity of HF or HCl, leading to issues such as structural defects in the MXene sheets and severe corrosiveness due to the acidic nature of these etchants. This study proposes a mild in situ etching strategy for the preparation of MXene materials through hexafluoro complex anion hydrolysis etching. Etching is accomplished by gradually introducing water into a suspension composed of hexafluoro complex, ethanol, and Ti3AlC2. This process results in the production of high-quality MXene in a mild reaction environment with the weak acidity of the solution, making it suitable for scalable synthesis and process applications. Moreover, the inclusion of ethanol in the etching process increases the interlamellar spacing of MXene, thereby facilitating the stripping process and ultimately yielding of 28% in the production of single-layer MXene through shaking. The MXene incorporated into the Si/C anode demonstrates a notable reversible cycling capacity of 563 mAh g−1 after 120 cycles, accompanied by an initial coulombic efficiency (CE) of 83%, surpassing the performance of Si/C anodes modified with carbon nanotubes (CNTs) and Super P. The approach presented in this study offers a promising pathway for the safe, straightforward, and sustainable production of high-quality MXene materials.