Graphene, the eternally stretching two-dimensional form of carbon, is one of the most promising synthetic materials in existence, but is still costly to produce to specification. New research released in the PNAS shows a simple and cheap way to produce the stuff, and could herald a graphene revolution.
The technique involves taking graphite and frozen carbon dioxide, and putting them into a ball miller — a rotating chamber filled with stainless steel balls. After two days of tumbling, the graphite forms flakes with open, carboxylated edges. These flakes are soluble in protic and polar aprotic solvents, and once dispersed, the flakes form graphene nanosheets of five or fewer layers.
Those carboxylated edges are what make this really cool — imagine them like Lego joins: they allow the graphene flakes to lock together. The nanosheets can be compressed into any shape, and then baked at 900°C, which closes the edges and forms a cohesive bond. Pellets of graphene made this way were 688 times better at conducting electricity than pellets made of graphene formed by the acid oxidation of graphite. To make large sheets of graphene, the researchers made a series of 3.5x5cm wafer, which were laid down and baked together, their edges joining.
By using different ingredients and solvents, "you can customize the edges for different applications," researcher Jong-Beom Baek said. "You can customize for electronics, supercapacitors, metal-free catalysts to replace platinum in fuel cells. You can customize the edges to assemble in two-dimensional and three-dimensional structures."
Image from Wikimedia Commons.