One-step synthesis of two-dimensional Ti3C2 and its electrochemical performance

Two-dimensional transition metal carbides and carbonitrides (MXenes) are the latest additions of the 2D world, which can be obtained by selective etching the a atomic layers from layered MAX precursors. In the traditional method of preparing MXene, the commonly used etchant is hydrofluoric acid. However, the use of concentrated hydrofluoric acid may inevitably bring about safety problems and even the destruction of crystal structure, resulting in the deterioration of intrinsic physical and chemical properties. This article starts from the typical carbide precursor Ti3AlC2 and uses NH4BF4 as an etchant to effectively reduce the amount of acid used in the system. More importantly, during the reaction process, the A layers were etched accompanied by intercalation of NH+4, by which the interlayer spacing was expanded and interlayer interaction was greatly weakened. High exfoliation efficiency of 2D Ti3C2 with intact crystallinities exfoliation was realized by a sequent hand shaking process. The electrochemical performance of as-obtained Ti3C2 was further characterized, showing an excellent capacitive electrochemical performance (503 F∙g-1 at a scan rate of 5 mV∙s-1) and cycling stability (the capacitance retention rate is 95.8% at 5 A·g-1 after 104 cycles). This provides new ideas for the synthesis and application of Ti3C2 nanosheets.