Few-layered Ti 3 C 2 T X coupled with Fe 3 O 4 nanoparticles assembled in a reduced graphene oxide hydrogel as advanced electrodes for high-energy supercapacitors

The design of advanced electrode materials with high energy density is the key for the practical application of supercapacitors (SCs) in portable digital devices. In this work, a novel heterostructure of Fe 3 O 4 nanoparticles anchored on Ti 3 C 2 T X was synthesized via a simple hydrothermal technique without any templates, and the heterostructure was successfully assembled into a 3D porous hydrogel by a hydrothermal graphene oxide (GO)-gelation self-assembly process at low temperatures. The resulting Fe 3 O 4 @Ti 3 C 2 T X -reduced graphene oxide (rGO) hydrogel can be directly used as the electrode of a SC without binders, due to the excellent mechanical strength of the macroscopic framework. The free-standing electrode presented a high specific capacitance of 308 F g −1 at 1 A g −1 , a maximal energy density of 45 W h Kg −1 at a power density of 362.4 W Kg −1 , and good cyclability with only 0.13% capacity loss from the 700th to the 1600th cycle at 10 A g −1 . These outstanding electrochemical performances of the Fe 3 O 4 @Ti 3 C 2 T X –rGO hydrogel can be attributed to the synergistic effect among each component and the 3D porous interconnected structure, which lead to high conductivity, repressive aggregation, and large active area. This work indicates that the proposed strategy can provide more opportunities to rationally develop MXene-based functional materials with high capacitive properties, which will extend the application of such materials to energy storage.