Interface engineering based NiCoMoO₄/Ti₃C₂T_x MXene heterostructure for high-performance flexible supercapacitors

The advancement of interface engineering has demonstrated remarkable efficacy in overcoming the primary impediment associated with sluggish reaction kinetics in supercapacitor electrodes. In this investigation, we employed a facile co-precipitation method to synthesize NiCoMoO₄/MXene heterostructures utilizing Ti₃C₂T_x MXene nanosheets as carriers. This heterostructure inhibits the restacking of MXene nanosheets and simultaneously enhances the exposure of electrochemically active sites in NiCoMoO₄ nanorods, thereby mitigating the reduction in specific capacitance resulting from volumetric fluctuations. The NiCoMoO₄/MXene electrode, possessing pseudo-capacitance properties, demonstrates an impressive level of specific capacitance, exceptional performance across various charging rates, and consistent behavior throughout repeated cycles. By optimizing the mass ratio, this electrode achieves a specific capacity of 1900 F/g under a current density of 1 A/g. Even after enduring 10,000 cycles at a significantly higher current density of 5 A/g, it still maintains an impressive retention rate of 94.73 %. Our density functional theory (DFT) calculations indicate that the enhanced electrochemical performance can be attributed to the improved electronic coupling within the NiCoMoO₄/MXene heterostructure. The integration of NiCoMoO₄/MXene cathode and activated carbon (AC) anode with an alkaline gel electrolyte containing potassium ferricyanide in flexible quasi-solid-state supercapacitors (FSSCs) results in exceptional electrochemical performance and flexibility. These FSSCs demonstrate a maximum energy density of 72.89 Wh kg^-1 at a power density of 850 W kg^-1, while maintaining an impressive power output of 16,780 W kg^-1 with an energy density of 37.28 Wh kg^-1. Based on these outstanding properties, it is evident that the NiCoMoO₄/MXene heterojunction possesses significant advantages as electrode material for supercapacitors, and the fabricated FSSCs devices pave a new pathway for flexible electronic devices.