Role of Surface Templating on Ice Nucleation Efficiency on a Silver Iodide Surface
Z Liu and C Li and EC Goonetilleke and Y Cui and XH Huang, JOURNAL OF PHYSICAL CHEMISTRY C, 125, 18857-18865 (2021).
Heterogeneous ice nucleation (HIN) can occur with the help of foreign particles or an external gas flow and is ubiquitous in nature. However, the molecular features of the surface that trigger nucleation remain largely elusive. Silver iodide (AgI), being one of the most commonly known ice nucleating agents (INAs), provides a model system to investigate the kinetics of the HIN. In this study, we use extensive all-atom molecular dynamics simulations to elucidate two important molecular features that can promote ice nucleation on the AgI surface: lattice match between the surface and its parallel ice plane and atomic surface roughness that is out-of-plane relative to ice. Specifically, we observe that a perfect lattice match between the surface and the ice plane results in the greatest in-plane templating effect by the AgI surface. Consequently, ice nucleation is enhanced and reaches the maximal nucleation rate. More interestingly, we find that the out-of- plane templating effect due to the atomic surface roughness can also increase the ice nucleation rate by a factor of 2 or 3. These enhancements originate from the underlying AgI surface, which can template a more ice-like first hydration layer with lower energy and subsequently promote ice formation. Our work provides new insights into how the templating effects of the AgI surface impact ice nucleation and sheds light on the rational design of INAs to control crystal nucleation events.
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