A generalized formula for two-dimensional diffusion of CO in graphene nanoslits with different Pt loadings

Catalytic performance of supported metal catalysts not only depends on the reactivity of metal, but also the adsorption and diffusion properties of gas molecules which are usually affected by many factors, such as temperature, pressure, properties of metal clusters and substrates, etc. To explore the impact of each of these macroscopic factors, we simulated the movement of CO molecules confined in graphene nanoslits with or without supported Pt nanoparticles. The results of molecular dynamics simulations show that the diffusion of gas molecules is accelerated with high temperature, low pressure or low surface-atom number of supported metals. Notably, the supported metal nanoparticles greatly affect the gas diffusion due to the adsorption of gas molecules. Furthermore, to bridge a quantitative relationship between microscopic simulation and macroscopic properties, a generalized formula is derived from the simulation data to calculate the diffusion coefficient. This work helps to advise the diffusion modulation of gas molecules via structural design of catalysts and regulation of reaction conditions.