Two-dimensional V4C3 MXene as high performance electrode materials for supercapacitors

Abstract

Two-dimensional (2D) MXenes such as Ti3C2, Ti2C, Mo2C, and Mo1.33C have shown excellent electrochemical performances as supercapacitor electrodes, and the exploration of new and/or high-capacity MXene-based supercapacitor electrode materials is an active field. In this work, 2D multi-layered V4C3 MXene has been synthesized by selectively etching Al from V4AlC3 and it shows a high capacitance of 209 F g−1 at 2 mV s−1, good rate performance, and stable long cyclic performance with capacitance retention rate of 97.23% after 10000 cycles at 10 A g−1 in 1 M H2SO4. Importantly, the pseudocapacitance (∼100.1 F g−1) accounts for about 37% of the total capacity (∼268.5 F g−1) for V4C3 MXene electrode. Therefore, the high specific capacitance of V4C3 MXene is not only due to their wide interlayer spacing (∼0.466 nm), large specific surface areas (∼31.35 m2 g−1) and pore volumes (∼0.047 cm3 g−1), and good hydrophilicity but also attributed to the abundant valence states of vanadium (+2, +3, and +4). The high rate performance and excellent cycling stability of V4C3 MXene electrodes are mainly attributed to the high electronic conductivity (1137 S m−1 at 300 K). The present work provides another promising MXene-based supercapacitor electrode material.