Researchers at Rice University have constructed a graphene foam, reinforced by carbon nanotubes, that can support more than 3,000 times its own weight and bounce back to its original height. In addition, its shape and size are easily controlled - which the team demonstrated by creating a screw-shaped piece of the material.
The 3D structures were created from a powdered nickel catalyst, surfactant-wrapped multiwall nanotubes and sugar as a carbon source. The materials were mixed and the water evaporated; the resulting pellets were pressed into a steel die and then heated in a chemical vapor deposition furnace, which turned the available carbon into graphene. After further processing to remove remnants of nickel, the result was an all-carbon foam in the shape of the die, in this case a screw. The team said the method will be easy to scale up.
The Rice team tested the new “rebar graphene” as a highly porous, conductive electrode in lithium ion capacitors and found it to be mechanically and chemically stable. The team had previously created graphene foam, but stated that "it wasn’t tough enough for the kind of applications we had in mind, so using carbon nanotubes to reinforce it was a natural next step".