Hydrogen domains in graphene: formation mechanisms

The underlying mechanisms of stable hydrogen domain formation in graphene produced by plasma-chemical synthesis are explored through molecular dynamics simulations. This process involves the pyrolysis of methane in an argon plasma. Experiments have demonstrated that the gas phase contains high concentrations of carbon and molecular hydrogen, as well as hydrogen-containing radicals. This results in hydrogen adsorption onto the basal planes of graphene and intercalation between adjacent layers. Atomistic simulations reveal that stabilisation critically depends on adhesive forces at the peripheral graphene edges, which create an effective kinetic barrier that suppresses hydrogen desorption from the interlayer space. The efficiency of confinement is highly dependent on layer multiplicity: trilayer architectures demonstrate near-optimal retention with negligible losses, whereas nine-layer stacks exhibit significantly reduced capacity. In multilayer systems comprising more than ten graphene sheets, domain nucleation and growth are restricted due to insufficient edge adhesion and increased interlayer rigidity. Within interlayer nanocavities, hydrogen predominantly remains in a molecular state within the synthesised structures. This molecular form allows reversible desorption at moderate temperatures (300 – 350°C) and prevents the degradation of the carbon framework. These findings confirm the fundamental feasibility of forming stable hydrogen nanocontainers directly during graphene growth. This offers a promising pathway for advanced solid-state storage materials and the synthesis process is also inherently scalable, facilitating potential industrial-scale production.

1. Work of MBSh and PPI was supported by the Ministry of Science and Higher Education of the Russian Federation (state assignment no. 075-00270-26-00). Work of JAB and KAK was supported by the State Assignment of IMSP RAS (Young scientist laboratory) -