Improved pseudocapacitances of supercapacitors based on electrodes of nitrogen-doped Ti3C2Tx nanosheets with in-situ growth of carbon nanotubes

Abstract A facile strategy involving only liquid mixing, drying, and annealing processes has been designed to fabricate a new MXene-based material containing nitrogen-doped carbon nanotubes grown on the nitrogen-modified titanium carbides (NCMX). During the thermal treatment, the nitrogen doping is dually achieved in MXene nanosheets and carbon nanotubes while the in-situ growth of carbon nanotubes occurs. The NCMX electrode exhibits the well-designed structure with the promoted specific surface area and specific capacitance. More attractively, the resultant NCMX-4 material shows extraordinary improved electrochemical capacitances of 299.52 F g-1 at the scan rate of 2 mV s-1 in the 3 M H2SO4 electrolyte, which is remarkably more superior than those of the pure un-doped one (74.98 F g-1). It delivers an excellent capacitance retention capability of 84.2% after 10000 cycles. Our results highlight that the strategy of fabricating novel NCMX materials here can be readily applied to a large industrial scale for improving the pseudocapacitance of supercapacitors.