Varghese Binu, Sathian Sarith P
Department of Applied Mechanics, Indian Institute of Technology, Madras, Chennai, Tamil Nadu, India.
Phys Chem Chem Phys. 2022 Sep 21;24(36):22298-22308. doi: 10.1039/d2cp03357g.
The development of the interfacial gas enrichment layer at the solid-liquid interface is coupled with the stability of surface nanobubbles. Depending upon the concentration of gas molecules, solid-liquid-gas interaction strengths, and other thermodynamic parameters, gas molecules can take several different forms such as dense gas layer, bulk and surface nanobubble, and other gaseous domains. Using molecular dynamics simulations we study the characteristics of gas accumulation into a dense gas layer, surface nanobubble and local gas aggregation at the graphene-water interface with no pinning sites. We find that gas molecules can migrate over the solid surface and can collect together to take the morphological form of a surface nanobubble. The developed nanobubble is mobile and can move over the homogeneous hydrophobic solid surface without losing its shape. We find that the gas adsorption on surfaces in the presence of a solvent is strongly affected by the wetting characteristics of the solid. In the absence of a solvent, gas adsorption is found to be universal for all surface types. Individual gas adsorption is found to be prominent and occurs in a short period, and is essential for the stability of the formed gaseous domains. Simulation results show gas adsorption density on surfaces to have a strong dependence on the solid-liquid interaction parameter than on solid-gas interaction strength.
固液界面处界面气体富集层的形成与表面纳米气泡的稳定性相关联。根据气体分子的浓度、固液气相互作用强度以及其他热力学参数，气体分子可以呈现几种不同的形式，如致密气体层、本体和表面纳米气泡以及其他气态区域。利用分子动力学模拟，我们研究了在没有钉扎位点的石墨烯 - 水界面处气体积累形成致密气体层、表面纳米气泡和局部气体聚集的特性。我们发现气体分子可以在固体表面迁移，并能够聚集在一起形成表面纳米气泡的形态。形成的纳米气泡是可移动的，并且可以在均匀的疏水固体表面上移动而不改变其形状。我们发现，在有溶剂存在的情况下，气体在表面上的吸附受到固体润湿性的强烈影响。在没有溶剂的情况下，发现气体吸附对于所有表面类型都是普遍存在的。单个气体吸附很显著且在短时间内发生，并且对于形成的气态区域的稳定性至关重要。模拟结果表明，表面上的气体吸附密度对固液相互作用参数的依赖性比对固气相互作用强度的依赖性更强。
