Direct synthesis of graphene/carbon nanotube hybrid films from multiwalled carbon nanotubes on copper

Graphene and carbon nanotube (CNT) (G/CNT) hybrid films have recently attracted great attention due to their potential of combining the merits of both one-dimensional (1D) and two-dimensional (2D) nanostructures. Here, we report a facile approach to form G/CNT hybrid films by thermal annealing of multiwalled carbon nanotube (MWNT) networks on copper foils. At elevated temperature and in the presence of hydrogen, MWNTs are partially etched to form active carbon species which then nucleate and grow graphene on copper until the formation of a continuous G/CNT hybrid film. We find that copper plays an important role in catalyzing the etching of MWNTs by hydrogen, as no etching has been observed for MWNTs on Si/SiO2 substrates under similar conditions. The obtained G/CNT hybrid films exhibit enhanced electrical stability under mechanical stress compared to CVD-grown graphene films.