While graphene has superior conductivity properties, it cannot be used as a direct replacement for silicon in semiconductors as it does not have a bandgap. However, hydrogenation of graphene provides a bandgap, which offers the prospect of it acting as a semiconductor component in new devices.
While other work has looked at the hydrogenation of bulk materials, the CMCM study focuses on hydrogenation of single and few-layers thick graphene. The scientists used a reaction based on lithium dissolved in ammonia to introduce hydrogen through the formation of C-H bonds.
The team discovered that hydrogenation proceeds rapidly over the entire surface of single-layer graphene, while it proceeds slowly and from the edges in few-layer graphene.
Using bilayer and trilayer graphene, the scientists also discovered that the reagents can pass between the layers, hydrogenating each layer equally well. Finally, they found that hydrogenation changed the optical and electric properties of graphene significantly.
“By building a deep understanding of the chemistry of single-layer graphene and a few layer graphene, I am confident that many new applications of chemically functionalised graphenes could be possible, in electronics, photonics, optoelectronics, sensors, composites and other areas,” said Professor Rodney Ruoff, CMCM director.