Hexaazatriphenylene-doped MXene films for the high-performance micro-supercapacitors and wearable pressure sensor system

Abstract

Two-dimensional MXene nanosheets have found extensive applications in portable electronic devices and flexible energy storage systems. However, the self-stacking effect caused by van der Waals forces severely restricts the rapid transport of electrolyte ions, thereby impacting the electrochemical performance. Here, nitrogen-doped MXene nanosheets (MXene-H) were obtained via surface modification of MXene with hexaazidotriphenylene (HAT) derivatives. The nitrogen atoms introduced between the layers act as pillars, widening the layer spacing and exposing more electrochemically active sites. By optimizing the doping ratio, the MXene-H micro-supercapacitor (MXene-H-MSC) exhibits outstanding electrochemical performance, with an area capacitance of 210.1 mF/cm2 and an energy density of 29.18 mWh/cm2, significantly surpassing that of previously reported MXene-based micro-supercapacitors. Moreover, the MXene-H-MSC demonstrates excellent cycling stability and flexibility, retaining 95% capacitance after 10,000 cycles, with no significant capacitance degradation observed in the CV curves tested at different angles. Furthermore, a micro-integrated system composed of the MXene-H-MSC and an MXene hydrogel pressure sensor in series can effectively respond to small changes in body movements, including speaking and finger flexing. This work provides potential guidance for research into the next generation of microelectronics.