The preparation of hybrid films of carbon nanotubes and nano-graphite/graphene with excellent mechanical and electrical properties

We have prepared mixed dispersions of singlewalled nanotubes and nano-graphite/graphene in the solvent N-methyl pyrrolidone. This allows the deposition of hybrid films by vacuum filtration. Scanning electron microscopy shows the components to be well mixed with little sign of phase separation. Although dominated by nano-graphite, Raman spectroscopy shows the presence of some graphene flakes with <5 layers. Mechanical measurements show the hybrids to be stronger and stiffer than nanotube or graphene-only films, reaching strengths and stiffnesses of 38 MPa and 4.8 GPa, respectively for the sample with 20 wt% graphene. In addition the hybrid films were more electrically conductive than the nanotube-only or graphitic films reaching a DC conductivity of 2 × 10⁴ S/m for the 70 wt% nano-graphite/graphene sample.