Size of Nanoscale Domains in Inhomogeneous Surfaces Determines Ice Nucleation

The microscopic mechanism of heterogeneous ice nucleation on various material surfaces is essential to controlling the freezing of water for wide applications, but it remains unclear. We investigated the ice nucleation on the inhomogeneous surfaces composed of nanosized hydrophobic and hydrophilic patterns by molecular simulations and found that the ice nucleation preferred a single hydrophobic/hydrophilic pattern rather than crossing over the boundary of neighboring patterns because of the higher freeenergy barrier in the latter in comparison with that in the former. Thus, these nanosized patterns behave as effective active domains of ice nucleation only while the size of the patterns is large enough to hold the critical ice nucleus. We further simulated the graphene oxide surfaces which are modeled by an ideal graphene surface by randomly replacing some carbon atoms with oxygen atoms and verified the picture in which the active nucleation regions of graphene oxide surfaces (the pure carbon or oxygen regions) can obviously promote ice nucleation only while the size is sufficiently large. This study indicates the importance of the nanometer-size structure of material surfaces in regulating the heterogeneous ice nucleation.