CNT-Reinforced Graphene Gets Big and Tough

Graphene foam invented at Rice University is reinforced with carbon nanotubes. It can hold thousands of times its own weight and still bounce back to its full height. Courtesy of the Tour Group
RICE UNIVERSITY’s CNT-REINFORCED GRAPHENE

A new type of conductive graphene foam is incredibly tough and better yet, it can be formed in just about any shape and size.

A chunk of carbon nanotube (CNT) reinforced conductive graphene foam can support more than 3,000 times its own weight and easily regain back its original height, scientists at Rice University reported, demonstrating a screw-shaped piece of the highly conductive foam.

The lab of chemist James Tour in Rice University tested its new “rebar graphene” as a highly porous, conductive electrode in lithium ion capacitors. They found it to be mechanically and chemically stable.

Their research appears in the American Chemical Society journal ACS Applied Materials and Interfaces.

Graphene foam invented at Rice University is reinforced with carbon nanotubes. It can hold thousands of times its own weight and still bounce back to its full height.
Graphene foam invented at Rice University is reinforced with carbon nanotubes. It can hold thousands of times its own weight and still bounce back to its full height. Courtesy of the Tour Group

Carbon in the form of atom-thin graphene is among the strongest of materials known and is highly conductive; multiwalled carbon nanotubes (MWCNTs) are widely used as conductive reinforcements in metals, polymers and carbon matrix composites.

The Tour lab had already used nanotubes to reinforce two-dimensional sheets of graphene.

Extending the concept to macroscale materials made sense, said Tour, a professor of computer science and of materials science and nanoengineering.

LAB PROCESSING METHOD

The lab created 3-dimensional structures using sugar as a carbon source, surfactant-wrapped multiwall nanotubes and powdered nickel as a catalyst.

The ingredients were agitated till the complete evaporation of water; the obtained pellets then pressed into a steel die and annealed in a chemical vapor deposition furnace, which turned the available carbon into graphene.

With further processing to remove remnants of nickel, the resulting foam was an all-carbon foam in the shape of the dye, here a screw. Tour said the method will be easy to scale up.

“We developed graphene foam, but 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,” Tour said.

CNT-Reinforced Graphene: A microscope image of rebar graphene shows carbon shells, multiwalled carbon nanotubes and two-dimensional graphene.
A microscope image of rebar graphene shows carbon shells, multiwalled carbon nanotubes and two-dimensional graphene. Courtesy of the Tour Group

Electron microscopic images of the foam showed partially unzipped outer layers of the nanotubes had bonded to the graphene, which accounted for its strength and resilience.

Rebar graphene irreversibly deformed by about 25 percent when loaded with more than 8,500 times its weight while graphene foam produced without the rebar could support only about 150 times its own weight while still retaining the ability to rapidly return to its full height.

Other researchers from Rice University and Tianjin University in China contributed to the work. The Air Force Office of Scientific Research and its Multidisciplinary University Research Initiative supported the research.

 

If you want to know more, check the original study that was published here.

Source Rice University American Chemical Society

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