High capacitance of dipicolinic acid-intercalated MXene in neutral water-based electrolyte

As an emerging family of conductive 2D materials, MXenes, have gained much attention as electrode in supercapacitor devices. Their representative, Ti 3 C 2 T x , usually achieves significant capacitance in common acid electrolyte. In this work, through a simple dipicolinic acid (DC) intercalation strategy, Ti 3 C 2 T x -DC can obtain outstanding capacitance in a more environmentally friendly KCl aqueous electrolyte. As a consequence, as an electrode for supercapacitor, Ti 3 C 2 T x -DC exhibits an outstanding specific capacitance of 353 F g −1 at a current density of 0.5 A g −1 in KCl aqueous electrolyte (MXene-DC/KCl), which is higher than MXene of 320 F g −1 in H 2 SO 4 electrolyte (MXene/H 2 SO 4 ) and MXene of 127 F g −1 in KCl aqueous electrolyte (MXene/KCl). Moreover, the MXene-DC/KCl shows an impressive cycling stability with about 100% capacitance retention after 10,000 cycles at 1.0 A g −1 . Such excellent electrochemical performance in a greener electrolyte is mainly attributed to the interlayer hydration of DC and counter ion adsorption of electrolyte.