Molecular Diffusion In Two-dimension Confined Nano-slits By Molecular Dynamics Simulation

The development of nanomaterials plays an important role in industrial production.The nano-confined space is give rise a great significance to catalysis,fluid transport and gas separation.In this paper,the molecular dynamics method based on Reax FF reaction field is carried out to reveal the mechanism of molecular diffusion transmission in the nano-slits formed by stacking of two-dimensional materials.And the objects of study including anatase titanium dioxide(101),graphene and ?-graphyne nanosheets,which provide three different properties of channel surface.We study the distribution and diffusion behavior of benzene,phenol and methane in the titanium dioxide(101)and graphene nanosheets.H2,H2 O,CO and CO2 are regarded as guest molecules in the ?-graphyne interlayer system during the simulation.The results showed that benzene and phenol molecules are restricted in the nano-confined space,because of their large size,resulting in drastic collision and obvious diffusion resistance in the narrow channel.The diffusion of phenol molecules in the titanium dioxide(101)interlayer is severely restricted indicating that the chemical reaction during the transfer process leads to the slowdown of diffusion.The molecules in the titanium dioxide and the graphene systems converge toward the near surface area as the confined space becomes larger.A typical depletion layer is observed at the two graphene surfaces,which reduces the collision frequency of the molecules and the surface.Graphyne allows H2 to pass through its own nano-pores,and its effect on H2 is negligible.The diffusion of H2 O molecules in the interlayer is stable and does not escape from the nano-pore.CO and CO2 are inhibited by their own molecular size and graphyne surface properties.In this paper,the molecular dynamics simulation method based on the ReaxFF is carried out to study the difference of samll molecules diffusion properties in the interlayer of the two-dimensional layered carbon-based materials and layered titanium dioxide materials.Through calculation and simulation,the paper try to make some reasonable mechanism analysis and explanation to relatived experimental phenomena.