Fabrication of graphene-carbon nanotube papers decorated with manganese oxide nanoneedles on the graphene sheets for supercapacitors

Herein, 3D nanohybrid architectures consisting of MnO₂ nanoneedles, carbon nanotubes (CNTs) and graphene sheets are fabricated. Nanostructured ternary hybrid papers in which MnO₂ nanoneedles formed on the outermost graphene layer and CNTs intercalated between graphene layers by using the amide bonds are fabricated using the direct paper dipping method. The intercalated CNTs can separate the graphene layers and thus create the effective surface area which is associated with large electrochemically active sites as well as form the electronic conductive channel inside the nanohybrid paper. Moreover, the homogeneous dispersion of nanometer-thick MnO₂ on the outermost graphene layer can maximize the surface area which can form pores for ion-buffering reservoirs to improve the diffusion rate of electrolyte ions and enable convenient participation in the pseudo-capacitive reaction. These nanostructured ternary hybrid papers exhibit enhanced specific capacitances compared with graphene-only or graphene-CNT papers. The proposed nanohybrid architectures are expected to lay the foundation for the design and fabrication of high-performance electrodes.