Investigation of Commercial Graphenes

For graphene to achieve its full scientific and commercial potential, reliable mass production of the material on the multi‐tonne scale is essential. We have investigated five samples of graphene obtained from commercial sources that state they can supply the product on the tonne scale per annum. From electron microscopy at the micrometre to the nanometre scale, and neutron vibrational spectroscopy, we find that none of the materials examined were 100 % isolated graphene sheets. In all cases, there was a substantial content of graphite‐like material. The samples exhibited varying oxygen contents, this could be present as carboxylic acid (although other oxygenates, quinones, phenols may also be present) or water. We emphasise that INS spectroscopy is particularly useful for the investigation of inorganic materials that will be used commercially: it provides atomic scale information from macroscopic (10’s of g) amounts of sample, thus ensuring that the results are truly representative.
Commercial graphenes from five different sources have been investigated. None of them are present as 100 % isolated sheets, rather they are present as stacks as shown by tilting experiments in the TEM: left, flat on the support, right, tilted 90°. Neutron vibrational spectroscopy of bulk quantities (10’s of g) shows that there are a variety of chemical functionalities and species present in the, nominally, graphene sheets.