Synthesis of High-Quality Two-Dimensional V2C MXene for Supercapacitor Application †

Two-dimensional (2D) V2C MXene has fascinating potential for use as electrodes in high-energy-density supercapacitors because of its excellent electrical conductivity and large specific surface area. However, it is not feasible to synthesize V2C by etching vanadium carbon aluminide (V2AlC) with hydrofluoric acid, which is commonly used for preparing other MXenes. In this work, a modified method is developed for synthesizing high-quality 2D V2C. A mixture of sodium fluoride (NaF) and hydrochloric acid (HCl) was used as the etching agent, where V2AlC can be gently etched by a hydrothermal reactor-assisted method. As electrode materials for supercapacitors, V2C shows the characteristics of electric double layer capacitance. The electrochemical results show high specific capacitance (223.5 F/g in 1 M Na2SO4 at a current density of 100 mA/g) and good cycling stability (the capacitance retention rate can be maintained at 94.7% after 5000 cycles). This work provides a new method for the synthesis of high-quality V2C for application in related fields.