Dopamine-derived N-doped carbon decorated titanium carbide composite for enhanced supercapacitive performance

Two-dimensional transition metal carbides, MXenes, with large surface area, excellent electrical conductivity and chemical stability, have proved promising for energy storage. However, the irreversible re-stacking and low capacity of MXenes restrict their development and practical applications. Here, the N-doped carbon decorated MXene (Ti 3 C 2 T x @NC) composites were synthesized via an in-situ self-polymerization of dopamine on the surface of Ti 3 C 2 T x followed by a carbonization process. The Ti 3 C 2 T x and Ti 3 C 2 T x @NC were systematically characterized, which have been manifested that NC were equably decorated on the surface and interlayer of Ti 3 C 2 T x sheets and a unique three-dimensional composited nanostructure was fabricated. Such nanostructure can confer both high surface area of NC layer and effective avoidance of the restacking of Ti 3 C 2 T x sheets, whilst, importantly, rendering the composites good conductivity and additional pseudocapacitance. As a result, the optimized Ti 3 C 2 T x @NC-2 composite exhibited a high specific capacitance of 442.2   F   g −1 under a current density of 1   A   g −1 , which is 281% higher than that of Ti 3 C 2 T x . As a further description, Ti 3 C 2 T x @NC achieved an excellent cycling stability with capacitance retaining 91.9% after 5000 cycles and a high rate capability of 92.5% at 10   A   g −1 . Besides, the Ti 3 C 2 T x @NC-2-based symmetric supercapacitor presents a delighted energy density and power density. Therefore, the elaborately designed Ti 3 C 2 T x @NC composites provided a pregnant exploration for energy-related applications.