Top-Down and Bottom-Up Graphene Production

Graphene, discovered at the University of Manchester in 2004, is a material with massive potential for future use. The lightest material known to humans, graphene is a thin graphite layer composed of carbon atoms in a hexagon shape.

Graphene possesses many attributes that make it exciting to scientists. Graphene is flexible and transparent. It is highly conductive and cannot be penetrated by most gasses and liquids. Scientists are eager to begin tests with graphene to develop new ways for trapping solar energy, filtering water, or creating new medical procedures. For this reason, the demand on graphene manufacturing companies is high.

Called the next silicon for its wide variety of possible uses, graphene is expensive and difficult to manufacture. Graphene manufacturers have developed two production methods: the top-down method and the bottom-up method.

Top-Down Production

Graphene was discovered by surprise when scientists Andre Geim and Konstantin Novoselov stuck scotch tape to a chunk of graphite and noticed that a fine layer of graphite remained on the tape after it was removed.

The concept of taking graphene from graphite crystals is behind the top-down method. One common top-down method, called “liquid phase exfoliation,” involves graphite crystals being treated with solvent chemicals. The solvent causes graphene to lift away from the graphite. In order to “seal” up the graphene, a stabilizing chemical is used to prevent the graphene from reverting to the crystal form.

Bottom-Up Production

While graphene was discovered through a top-down method, top-down production only creates small batches of graphene. In order for scientists to explore graphene’s possibilities, graphene manufacturing companies developed a more efficient method called chemical vapor deposition, or CVD.

While the top-down method takes graphene from an existing source, the bottom-up method actually “grows” new graphene. In this method, a strip-shaped copper substrate is heated to approximately 1000 degrees Celsius. The copper strip is then inserted into a tubular chamber.

Once the strip is inside the chamber, it’s sprayed with methane gas. The carbon and hydrogen atoms in the methane react with the copper, causing a film of graphene to form on the metal strip. After a layer of graphene covers the strip, the chamber temperature is lowered in order to “freeze” the graphene in its current state.

The CVD process allows graphene manufacturing companies to produce rolls of graphene for scientists around the world. As access to graphene grows, more opportunities to learn about its potential abound.

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