Molecular insights into surface wettability for heterogeneous ice nucleation of seawater on solid surfaces

Heterogeneous ice nucleation (HIN) of seawater on solid surfaces with varying wettability is a crucial stage in ice formation, which is common in nature and industrial applications. However, little research has focused on the effect of surface wettability on the HIN of seawater and its underlying mechanisms. In this study, the molecular dynamics method is employed to investigate the HIN characteristics of salt solutions on surfaces with varying wettability and clarify the effect of surface wettability. The results show that both the nucleation temperature and the nucleation rate of the salt solutions on solid surfaces increase with increasing surface wettability, which is attributed to the reduction of the free energy barrier. With the enhancement of binding energy between the salt ions and the solid surface, ion occupancy (the inhibition of the HIN) first increases and then tends to stabilize, thus the nucleation temperature of the salt solution first decreases and then keeps stable. The competition between the binding interactions of water molecules and salt ions with the solid surface determines the difficulty of the HIN of the salt solution. These findings contribute to a deeper understanding of the characteristics and physical mechanisms of the HIN of seawater on solid surfaces, providing valuable insights for the development of freeze desalination.