Synthesis and electrochemical properties of V2C MXene by etching in opened/closed environments

Abstract The effect of etching environment (opened or closed) on the synthesis and electrochemical properties of V 2 C MXene was studied. V 2 C MXene samples were synthesized by selectively etching of V 2 AlC at 90 °C in two different environments: opened environment (OE) in oil bath pans under atmosphere pressure and closed environment (CE) in hydrothermal reaction kettles under higher pressures. In OE, only NaF (sodium fluoride) + HCl (hydrochloric acid) etching solution can be used to synthesize highly pure V 2 C MXene. However, in CE, both LiF (lithium fluoride) + HCl and NaF+HCl etchant can be used to prepare V 2 C MXene. Moreover, the V 2 C MXene samples made in CE had higher purity and better-layered structure than those made in OE. Although the purity of V 2 C obtained by LiF+HCl is lower than that of V 2 C obtained using NaF+HCl, it shows better electrochemical performance as anodes of lithium-ion batteries (LIBs). Therefore, etching in CE is a better method for preparing highly pure V 2 C MXene, which provides a reference for expanding the synthesis methods of V 2 C with better electrochemical properties.