Molecular Insight into the Processes and Mechanisms of N₂ Adsorption and Accumulation at the Hydrophobic Solid/Liquid...

In this study, molecular dynamics (MD) simulations were employed to elucidate the processes and underlying mechanisms that govern the adsorption and accumulation of gas (represented by N₂) at the hydrophobic solid-liquid interface, using the GROMACS program with an AMBER force field. Our findings indicate that, regardless of surface roughness, the presence of water molecules is a prerequisite for the adsorption and aggregation of N₂ molecules on solid surfaces. N₂ molecules dissolved in water can cluster even without a solid substrate. In the gas-solid-liquid system, the exclusion of water molecules at the hydrophobic solid-liquid interface and the adsorption of N₂ molecules do not occur simultaneously. A loosely arranged layer of water molecules is initially formed on the hydrophobic solid surface. The two-stage process of N₂ molecule adsorption and accumulation at the hydrophobic solid/liquid interface involves initial adsorption to the solid surface, displacing water molecules, followed by N₂ accumulation via self-interaction after saturating the substrate's surface. The process and underlying mechanisms of gas adsorption and accumulation at hydrophobic solid/liquid interfaces elucidated in this study offer a molecular-level understanding of nano-gas layer formation.