| dc.description.abstract | Ab initio density-functional-theory-based calculations have been performed to investigate the gas adsorption properties on various materials, including the adsorption of molecular hydrogen on MXene monolayer and the adsorption of water on metal-organic frameworks. Especially, a multiscale modeling, which was the combination of density functional theory calculations, ab initio atomistic thermodynamic, and kinetic Monte Carlo approach, has been extensively employed to study the hydrogen adsorption on MXene Sc2C monolayer at different length and time scales. Results from density functional calculations unraveled the interaction mechanism between the involved molecular hydrogen and the surface, while the ab initio atomistic thermodynamic model evaluated the usable hydrogen uptake at different temperature and pressure ranges. The kinetic Monte Carlo model further validated the thermodynamic data and clarified the kinetic effect in adsorption/desorption processes that was the bottleneck in the ab initio atomistic thermodynamic model. Although those processes are fast and might be irrelevant to a realistic time-scale for applications, it was found that the Monte Carlo kinetic results exclude an optimistic description of the equilibrium which was often undertaken for ab initio molecular dynamic simulations. For the adsorption of water on metal-organic frameworks, a decomposition mechanism for Mn2(DSBDC) MOF was proposed. There are a couple of important factors leading to that decomposition, which are the easy clustering of water molecules, the distortion of the structure caused by the attraction between the coordinated waters and the linkers, and the insertion of water to occupy the linker bonds. The insertion of water is easy to occur that a low transition barrier has been found. | en_US |