Three representative freezing pathways for nuclei that start (a) at both interfaces, (b) at the free interface only, and (c) at the ice nucleating particle (here the graphene support). The ice nucleating particles and water droplets are depicted in dark red and light blue, respectively, on a graphene support (green). The number of molecules within the largest crystalline nucleus is given as the order parameter ξ. Each configuration is a progeny of the configuration to its left. Reproduced from1, copyright (2021) American Chemical Society.