| 论文简介 |
Graphene provides a possibility where gas adsorption energy is comparable with molecular collision energy for physically adsorbed gases, resulting in the incompetence of traditional hopping model to describe graphene-related surface diffusion phenomena. By calculating surface diffusion coefficients based on Einstein equation, we exactly demonstrate that the gas diffusion on graphene surface is a two-dimensional gas behavior mainly controlled by the collisions between adsorbed molecules. The surface diffusion on graphene film just follows the bulk diffusion qualitatively, namely the diffusion coefficients decrease with increasing gas pressure. In quantitative, the surface diffusion coefficients are lower than the bulk diffusion coefficients predicted by the hard sphere model owing to the restriction of graphene film. The reduction in diffusion coefficient is related to the simultaneously suppressed average frequency of molecular collisions and average travelling distance between successive collisions. In addition, a lower diffusion coefficient on a hydrogen-functionalized graphene surface is identified, caused by the blocking effects of chemical functional groups. |
(创新港)
