我們研究各種材料上的氣體吸附性能，包括分子氫在單層MXene(Sc2C)上的吸附和水在金屬有機框架上的吸附。我們建立一個多尺度建模的方法結合密度泛函理論計算、從頭算原子熱力學和動力學蒙特卡羅方法以究不同時間跟空間尺度下氫氣分子的吸附。密度泛函計算的結果揭示了所涉及的分子與表面之間的相互作用機制，而從頭原子熱力學模型評估了不同溫度和壓力範圍內氫氣的有效吸收。動力學蒙特卡羅模型進一步驗證了熱力學數據並闡明了氫氣吸附/解吸過程中的動力學效應，這是從頭算原子熱力學模型的瓶頸。儘管這些過程很快並且可能與實際的應用時間尺度有些距離，但發現蒙特卡羅動力學結果排除了從頭分子動力學模擬對平衡時的吸附過份樂觀描述。在了解金屬有機骨架中水的吸附，利用密度泛函提出了Mn2(DSBDC)的分解機制。導致這種分解的重要因素有幾個，它們是水分子的容易聚集、強極化吸引力引起的結構扭曲以及插入水以佔據連接鍵。;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.
