Growth of carbon nanotubes on graphene by chemical vapor deposition

Graphite oxide powder impregnated with an Ni(NO3)2 solution was freeze-dried, thermally-reduced at 300 oC and then chemical-vapor deposition at 1000 oC was used to grow carbon nanotubes (CNTs) on graphene using methane as the carbon source. The morphology and electrical conductivities of the graphite oxide, reduced graphene and CNT-graphene hybrids were characterized. Results indicate that the density of CNTs on the graphene and the electrical conductivity of the hybrids increase with increasing Ni(NO3)2 concentration in the solution. Isolated graphene lamellae were connected by CNTs, giving rise to a 3D conducting network that provided conducting channels for electron transport.