Abstract
The effect of etching environment (opened or closed) on the synthesis and electrochemical properties of V2C MXene was studied. V2C MXene samples were synthesized by selectively etching of V2AlC 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 V2C MXene. However, in CE, both LiF (lithium fluoride) + HCl and NaF+HCl etchant can be used to prepare V2C MXene. Moreover, the V2C MXene samples made in CE had higher purity and better-layered structure than those made in OE. Although the purity of V2C obtained by LiF+HCl is lower than that of V2C 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 V2C MXene, which provides a reference for expanding the synthesis methods of V2C with better electrochemical properties.
Highlights
MXenes is a family of novel two-dimensional materials that was successfully synthesized in 2011 [1]
The V2C MXene was prepared by selectively etching Al layers from the V2AlC MAX phase at 90 °C for 5 d in oil bath pans and hydrothermal reaction kettles, respectively
As shown in the bottom 2 patterns in Fig. 2(a), in closed environment (CE), both LiF+HCl and NaF+HCl can be used to synthesize V2C MXene, though the V2C MXene made by LiF+HCl etching was less pure
Summary
MXenes is a family of novel two-dimensional materials that was successfully synthesized in 2011 [1]. In the previous studies to synthesize V2C MXene [9,24,25,26,28], the effects of etching solution, temperature, time, and precursor phase activity were thoroughly studied. Another important factor, the environment in which the etching was processed, was not considered. The etching processes to synthesize V2C MXene were carried in oil bath pans (OE) or hydrothermal reaction kettles (CE), respectively, and other factors were the same, including temperature, time, and etching solution. The effects of etching environment on the purity, microstructure, and performance as LIB anodes of V2C MXenes were clarified
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