Carbon nanotube cross-linked phosphorus-doped MXene for capacitive pressure microsensors

Abstract

The extreme mechanical flexibility, integration and wearability of one-dimensional carbon-based cross-linked two-dimensional MXenes can exactly meet the rapid development of microelectronic technology and medical microdevices, thereby achieving miniaturization and multi-functionality. Herein, a pressure microsensor was assembled using micro-supercapacitors of phosphorus-doped MXene cross-linked by carbon nanotubes. The carbon nanotube cross-linked phosphorus-doped MXene (P-MXene/CNT) is prepared by chemical vapor deposition and electrostatic self-assembly. The interdigital electrodes are obtained through mask-assisted vacuum filtration to integrate symmetrical micro-supercapacitors using a gel electrolyte. P-doping regulates the electron distribution of the MXene and improves the specific capacity. The P-MXene is cross-linked by carbon nanotubes to alleviate the self-stacking effect for accelerated ion transport. The P-MXene/CNT based planar micro-supercapacitor shows desirable mechanical flexibility and integrability with an extraordinary area capacitance of 162.4 mF cm⁻², an energy density of 32.9 μW h cm⁻², and a long-term cycling stability up to 91.3% after 10 000 cycles. The pressure microsensor illustrates an outstanding sensitivity toward external pressure and ensures an accurate and continuous detection of human body motions.