Ethylene diamine–assisted capillary impregnation of NiO@Ti3C2 MXene composites from MAX phase for enhanced supercapacitor applications

The development of sustainable, high-performance supercapacitors is essential for advancing next-generation energy storage technologies. In this work, Nickel Oxide (NiO)/Ti 3 C 2 MXene composites are designed to overcome the inherent self-stacking issue of MXenes while enhancing electrochemical properties. Ti 3 C 2 MXene nanosheets were prepared via selective etching of Ti 3 AlC 2 MAX phase using LiF/HCl, followed by the uniform incorporation of NiO nanoflakes through a novel ethylenediamine-assisted capillary impregnation process. Structural characterization confirmed the successful intercalation of NiO, which effectively prevented MXene restacking and provided additional surface sites for OH − ion adsorption and participation in redox reaction for charge storage. Ni 2+ ions form NiO nanoflakes between and on Ti 3 C 2 layers, enabling uniform dispersion and strong coupling. The Ni 2+ ↔ Ni 3 redox activity with Ti 3 C 2 conductivity enhances OH − accessibility and boosts capacitance. Electrochemical evaluations revealed that the optimized NiO@Ti 3 C 2 composite delivers a high specific capacitance of 256 F g −1 at 1 A g −1 , an energy density of 68 Wh kg −1 , and excellent cycling stability with 95% capacitance retention over 5000 cycles. The synergistic combination of the high conductivity of Ti 3 C 2 and the faradaic redox activity of NiO leads to superior electrochemical performance and structural durability. This strategy offers a promising and sustainable pathway toward the development of advanced supercapacitors for efficient energy storage applications.