Effect of electrolyte on supercapacitor performance of two-dimensional molybdenum carbide (Mo2CTx) MXene prepared by hydrothermal etching

In this work, highly pure Mo2CTx MXene was synthesized by acid etching in a hydrothermal reactor. And the electrode based on the Mo2CTx MXene for supercapacitors in seawater electrolyte exhibited better performance than other MXenes. The specific capacitance values in 1 M KOH, MgSO4 and H2SO4 electrolytes achieves 11.27, 18.97 and 79.14F g−1 at the current density of 0.3 A g−1, equivalent to the volumetric capacitance of 55.62, 93.66 and 390.74F cm−3 and remains 89.9%, 96% and 98% capacitance retention over 5000 cycles. [Display omitted] •DFT calculation is performed to exploration of a Mo2CTx MXene-based energy storage system.•Highly pure Mo2CTx MXene by acid etching in a hydrothermal reactor.•Mo2CTx MXene to construct numerous excellent properties in H2SO4 electrolyte. MXenes are widely used in energy storage and MXenes exhibits different electrochemical properties in different electrolytes. Here, density functional theory (DFT) calculation is performed to direct atomic scale exploration, design and assembly of a Mo2CTx MXene material-based energy storage system. The adsorption of H, K and Mg atoms on a Mo2CTx MXene are systematically investigated by first principles methods based on DFT calculations. Hence, we report on the preparation of Mo2CTx MXene by acid etching in a hydrothermal reactor. The performance of Mo2CTx MXene as supercapacitor (SC) electrode is systematically test in virous electrolytes. The specific capacitance values in 1 M KOH, MgSO4 and H2SO4 electrolytes achieves 11.27, 18.97 and 79.14F g−1 at the current density of 0.3 A g−1, equivalent to the volumetric capacitance of 55.62, 93.66 and 390.74F cm−3 and remains 89.9%, 96% and 98% capacitance retention over 5000 cycles. This study exhibits the potential of Mo2CTx MXene to construct numerous excellent properties in H2SO4 electrolyte.