Water freezing remains a perennial topic of great relevance to many important aspects of our lives; from the climate to human society and from economics to medicine, frozen water profoundly influences our living environment and life activities. There have been numerous publications on water freezing; however, confusion regarding the process of freezing remains. In this review, we mainly focused on the nucleation aspects of water freezing; in particular, we focused on the effect of the surface morphology and nanostructure of foreign bodies. This review covers the recent progress in ice nucleation and anti-freezing strategies within the framework of nucleation principles. In this regard, we first summarize the crystal nucleation theories. Due to high interfacial energy, ice crystallization is primarily controlled by heterogeneous nucleation events, because the homogeneous nucleation barrier of ice is extremely high. In addition to the interfacial energy, the interfacial morphology or nanostructure of foreign bodies plays a diverse role under different supercooling regimes due to the Gibbs–Thomson effect. This effect gives rise to the inverse homogeneous-like nucleation phenomenon, in which foreign bodies have little influence on the nucleation barrier. This ensures the accurate measurement of the nucleation barrier, critical size, and water–ice interfacial energy, in agreement with the latest studies based on a microemulsions approach, metadynamics, the mW model, etc. As a consequence, anti-freezing strategies can be implemented by reducing the nucleation rate through restriction of the contact area of the water/substrate interface, by increasing the heterogeneous nucleation barrier through modification of the interfacial properties of foreign particles, including the interfacial structure and the interaction between the water and foreign particles and by kink kinetics. Within this context, the anti-freezing mechanism of superhydrophobic substrates was reviewed. Therefore, it follows that by significantly reducing the contact area between the water and substrate, superhydrophobic materials can effectively reduce the heterogeneous nucleation rate. We hope that this review will provide a unified picture and guidance for future work on water freezing.

Study shows the repair of enamel via a biomimetic growth frontier that is constructed from calcium phosphate ion clusters.

Clathrate hydrates find diverse significant applications including but not limited to future energy resources, gas storage and transport, gas separation, water desalination, and refrigeration. Studies on the nucleation, growth, dissociation, and micro/nanoscale properties of clathrate hydrates that are of utmost importance for those applications are challenging by experiments but can be accessible by molecular simulations. By this method, however, identification of cage structures to extract useful insights is highly required. Herein, we introduce a hierarchical topology ring (HTR) algorithm to recognize cage structures with high efficiency and high accuracy. The HTR algorithm can identify all types of complete cages and is particularly optimized for hydrate identification in large-scale systems composed of millions of water molecules. Moreover, topological isomers of cages and n × guest@cage can be uniquely identified. Besides, we validate the use of HTR for the identification of cages of clathrate hydrates upon mechanical loads to failure.