Scientists use camera flash to turn insulating material into conductor

Washington, Aug 13: Can camera flash actually turn an insulating material into a conductor? Yes, if Northwestern University researchers are to be believed.

Lead researcher Jiaxing Huang, assistant professor of materials science and engineering at Northwestern's McCormick School of Engineering and Applied Science have found a novel way of turning graphite oxide - a low-cost insulator made by oxidizing graphite powder-into graphene, a material that conducts electricity.

Materials scientists previously have used high-temperature heating or chemical reduction to produce graphene from graphite oxide.

However, these techniques could be problematic when graphite oxide is mixed with something else, such as a polymer, because the polymer component may not survive the high-temperature treatment or could block the reducing chemical from reacting with graphite oxide.

During the study researchers simply held a consumer camera flash over the graphite oxide and, a flash later, the material became piece of fluffy graphene.

"The light pulse offers very efficient heating through the photothermal process, which is rapid, energy efficient and chemical-free," said Huang.

When using a light pulse, photothermal heating not only reduces the graphite oxide, it also fuses the insulating polymer with the graphene sheets, resulting in a welded conducting composite.

Using patterns printed on a simple overhead transparency film as a photo-mask, flash reduction creates patterned graphene films. This process creates electronically conducting patterns on the insulating graphite oxide film-essentially a flexible circuit.

The research group hopes to next create smaller circuits on a single graphite-oxide sheet at the single-atom layer level.

"If we can make a nano circuit on a single piece of graphite oxide. It will hold great promise for patterning electronic devices," said Huang.

The study is published in the Journal of the American Chemical Society.

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