Disordered Bulk Hydrogenated Graphene Revealed by X-ray and Neutron Scattering*

Defects and functionalization can be used to modify graphene’s physical properties such as changing its conductivity or inducing ferromagnetism, which could be of interest for spintronics.  Here we investigate hydrogenated graphene nano-powder that has been produced by Birch reduction of graphite oxide.  One significant challenge in assessing these materials is the ability to determine their atomic structure. By combining x-ray diffraction (XRD), neutron diffraction (ND), and transmission electron microscopy, we show that these materials contain a significant portion of highly disordered carbon. XRD and ND reveal that a small portion of these samples are 2-3 layers thick with a maximum interlayer spacing of 3.85 Å – a significant expansion compared to pristine few-layered graphene, indicating that some H may attach onto the graphene planes. Modeling the coherent diffuse scattering seen in XRD and ND as well as comparing the coherent and incoherent ND, we determine the H/C ratio and we conclude that these materials contain a structure that is quite different from the idealized graphane structure.