Graphene – a one-atom-thick layer of graphite – is a two-dimensional crystal composed of hexagonally bonded carbon atoms. The classic way of obtaining graphene, which was used by Nobel laureates Andre Geim and Konstantin Novoselov, is the exfoliation method. It comes down to reducing the number of monolayers in graphite. However, this method is not suitable for scaling up graphene production.
Scientists from the Institute of Catalysis SB RAS have attempted to solve this problem using a template method for obtaining graphene. “We took magnesium oxide as a template. We carbonised it with 1,3-butadiene at a temperature of 600°C, after which the template particles became coated with a thin carbon film. We then removed the magnesium oxide via hydrochloric acid. What was left was a graphene sheet, which we doped with phenylboric acid,” Vladimir Chesnokov, Doctor of Chemistry, is quoted as saying by the Institute of Catalysis SB RAS.
This method is not only easy to scale up, but also helps improve the properties of the carbon nanomaterial. The resulting graphene could, with the addition of boron, be used as sensors, sorbents and photocatalysts. In addition, it could replace platinum in fuel cells that convert the chemical energy of hydrogen into electricity.
A fuel cell consists of a conductive membrane, which is placed in the centre of two chambers. Oxygen is passed through one chamber and hydrogen through the other, with platinum applied on each side in order to act as a catalyst for the reaction. When hydrogen gives up an electron (a negatively charged particle), this results in a proton – a positively charged ion that, unlike an electron, has an internal structure and finite dimensions. The proton migrates through the membrane and interacts with oxygen, which is the basis for the operation of fuel cells.
“Graphene doped with boron is more cost-efficient to use in fuel cells than platinum. Firstly, carbon nanomaterial is much cheaper than platinum. Secondly, the surface of platinum gets covered with carbon monoxide during operation, which leads to its deactivation. This does not happen with graphene,” Vladimir Chesnokov concludes as reported by the Institute of Catalysis SB RAS.
