Temperature-dependent kinetic pathways of heterogeneous ice nucleation competing between classical and non-classical nucleation

Abstract

Ice nucleation on the surface plays a vital role in diverse areas, ranging from physics and cryobiology to atmospheric science. Compared to ice nucleation in the bulk, the water-surface interactions present in heterogeneous ice nucleation complicate the nucleation process, making heterogeneous ice nucleation less comprehended, especially the relationship between the kinetics and the structures of the critical ice nucleus. Here we combine Markov State Models and transition path theory to elucidate the ensemble pathways of heterogeneous ice nucleation. Our Markov State Models reveal that the classical one-step and non-classical two-step nucleation pathways can surprisingly co-exist with comparable fluxes at T = 230 K. Interestingly, we find that the disordered mixing of rhombic and hexagonal ice leads to a favorable configurational entropy that stabilizes the critical nucleus, facilitating the non-classical pathway. In contrast, the favorable energetics promotes the formation of hexagonal ice, resulting in the classical pathway. Furthermore, we discover that, at elevated temperatures, the nucleation process prefers to proceed via the classical pathway, as opposed to the non-classical pathway, since the potential energy contributions override the configurational entropy compensation. This study provides insights into the mechanisms of heterogeneous ice nucleation and sheds light on the rational designs to control crystallization processes.

Mesoscale clusters of organic solutes in solution and their role in crystal nucleation

“…90 For heterogeneous nucleation of ice, Markov state MD modelling suggests that the relative rates of classical and two-step nucleation can depend on temperature, with a transition point above which classical mechanism is predicted to dominate. 91…”

Size of Nanoscale Domains in Inhomogeneous Surfaces Determines Ice Nucleation

“…As shown in Figure S3, the free-energy profiles of ice nucleation on the chessboard-like surface with different sizes contain only one barrier, indicating that the nucleation process follows the picture of classical nucleation theory. Li et al , reported that on the hydrophilic wurtzite-structured surfaces the first water layer can form rhombic and hexagonal ice patches. The ice nucleation on these wurtzite-structured surfaces adopts complex pathways with the coexistence of classical and nonclassical nucleation pathways.…”

“Nanoreactors” for Boosting Gas Hydrate Formation toward Energy Storage Applications

“…This capability of forming a 3-D structure depends on the configuration of the first monolayer. When water molecules in the first monolayer have dangling OHs pointing away (Figure a), developing a 3-D network is possible because the dangling OHs can form interlayer hydrogen bonds to connect to the second monolayer of water . Then, from the second layer of water, the third layer can develop, and so forth.…”

“…When water molecules in the first monolayer have dangling OHs pointing away (Figure 11a), developing a 3-D network is possible because the dangling OHs can form interlayer hydrogen bonds to connect to the second monolayer of water. 80 Then, from the second layer of water, the third layer can develop, and so forth. In this case, the solid surface is playing a seeding role in the creation of a 3-D structure of water such as the nucleation of gas hydrates and ice.…”

“…In contrast, when water molecules in the first monolayer only form intralayer hydrogen bonds, and no dangling OHs are available for forming interlayer hydrogen bonds to the second monolayer of water (Figure 11b), the construction of a 3-D water structure is not possible. In this case, the second layer of water remains in a liquid state, 80 and the solid surface does not have any seeding roles. Therefore, two key factors enabling a solid surface to seed gas hydrate nucleation are (1) suitable solid−water interaction and (2) the ice-like molecular arrangement of the surface.…”