The Synthesis Process and Thermal Stability of V₂C MXene

The effect of etching solution on the synthesis process of two-dimensional vanadium carbide (V₂C MXene) was researched. Three etching solutions were used to etch ternary carbide V₂AlC at 90 °C. The three solutions were: lithium fluoride + hydrochloric acid (LiF + HCl), sodium fluoride + hydrochloric acid (LiF + HCl), and potassium fluoride + hydrochloric acid (KF + HCl). It was found that only NaF + HCl solution was effective for synthesizing highly pure V₂C MXene. The existence of sodium (Na⁺) and chloridion (Cl^-) in etching solution was essential for the synthesis. The thermal stability of the as-prepared V₂C MXene in argon or air was studied. From thermogravimetry and differential thermal analysis, V₂C MXene was found to be stable in argon atmosphere at a temperature of up to 375 °C. As the temperature increased, V₂C MXene was gradually oxidized to form nanoparticles composed of vanadium trioxide (V₂O₃) and a part of V₂C MXene was broken and transformed to vanadium carbide (V₈C₇) at 1000 °C. In air atmosphere, V₂C MXene was stable at 150 °C. At 1000 °C, V₂C MXene was oxidized to form vanadium pentoxide (V₂O₅).