Interfacial ice on graphene has attracted much attention because it is a model system to study two-dimensional (2D) ice structures on chemically inert substrates. While water-graphene interaction was usually assumed to be negligible, the structures of the 2D ice are believed to be not appreciably perturbed by the graphene substrate. Here we report atomic-resolved characterizations of an exotic 2D ice structure on graphene built from water molecular chains with finite lengths. Our experiments demonstrated that the water molecular chains are exactly orientated along zigzag directions of the graphene substrate, which evidences an anomalously strong interlayer interaction between the 2D ice and the graphene substrate. Moreover, the length of the water molecular chains closely links to the number of graphene layers, indicating layer-number-dependent water-graphene interfacial interactions. Our work highlights the important role of the 2D ice structures on the water-graphene interfacial interactions.
An established procedure for the estimation of ice-water interfacial energy based on evaluation of the slope of the experimental ice nucleation rate data versus scaled temperature is critically analyzed in this work. An inconsistent estimate of the ice-water interfacial energy is found in the work of Murray et al. [Phys. Chem. Chem. Phys., 2010, 12, 10380-10387]. The source of the inconsistency is identified in an inappropriate regression method used for experimental ice nucleation data fitting, a correct estimate of the ice-water interfacial energy is presented, and limits of the slope method…
We reanalyzed the measurements made by Asakawa et al. [1] of the growth velocities of single-molecule-high steps on basal ice surfaces, as we believe the authors made a number of incorrect assumptions regarding ice growth parameters and bulk diffusion in their experiments. Applying what we believe are more accurate assumptions, we used the data in [1] to derive a surface diffusion length of approximately 10 nm for water molecules on basal ice surfaces at -8.4 C, about 500 times lower than what was reported in [1]. Moreover, in our analysis we found that no information about the height of the E…
Few compounds feature ice-shaping properties. The only compound reported to have ice-shaping properties similar to that of ice-shaping proteins, encountered in many organisms living at low temperature, is Zirconium Acetate. When a Zirconium Acetate solution is frozen, oriented and perfectly hexagonal ice crystals can be formed and their growth follows the temperature gradient. To shed light on the water/ice phase transition while freezing Zirconium Acetate solution we carried out differential scanning calorimetry measurements. From our results, we estimate how many water molecules do not freez…
The main idea of the interstitial-ice model is that liquid water consists of an intact hexagonal lattice with both vacant lattice positions and interstitial water molecules. Narten, Danford and Levy derived the model parameters from the X-ray diffraction patterns of liquid water. However, their results were counter-intuitive: their model had almost no vacancies, the interstitial concentration was temperature independent and the ice lattice was deformed resulting in extra anisotropy. To overcome these problems, we refined the model and derived the model parameters from the proton nuclear magnet…
I consider the kinetics of water freezing and show that, at small sub-zero temperatures, (i) the time of ice nucleation within the bulk water environment is enormous and therefore cannot take place either in lakes of in living cells; (ii) that the ice nucleation needs some ice-binding surfaces to occur, but (iii) even this kind of ice nucleation can take place, as a rule, only at the temperatures that are a few degrees below 0oC. Further, I discuss factors that can drastically reduce the ice nucleation time at nearly-zero temperatures both in open reservoirs, where water contacts with air, and…
Graphene-water interaction has been under scrutiny ever since graphene discovery and realization of its exceptional properties. Several computational and experimental reports exist that have tried to look into the interactions involved, however, none of them addresses the issue in its entirety. We have tested the inherent hydrophobic behavior of a small graphene in water droplet by the means of MD simulations. The analysis has been extended to multiple graphene flakes in water and their respective size dependent responses to water droplet. Graphene retreats from water droplet to encapsulate it…
Water confined between two layers with separation of a few Angstrom forms layered two- dimensional ice structure. Using large scale molecular dynamics simulations with the adoptable ReaxFF interatomic potential we found that flat monolayer ice with a rhombic-square structure nucleates between graphene layers which is non-polar and non-ferroelectric. Two layers of water are found to crystallize into a square lattice close to the experimental found AA-stacking [G. Algara- Siller et al. Nature 519, 443445 (2015)]. Each layer has a net dipole moment which are in opposite direction. Bilayer ice is …
A mechanism for ice growth on the surface of a spherical water droplet
Nanchang University（南昌大学）；John A. Logan College（约翰·A·洛根学院）；Norwegian University of Science and Technology（挪威科技大学）；KTH Royal Institute of Technology（瑞典皇家理工学院）；Qingyuan Innovation Laboratory（清远创新实验室）；Centre of Excellence ENSEMBLE3 Sp. z o. o.（ENSEMBLE3卓越中心有限公司）；University of Warsaw（华沙大学）
We explore the Casimir-Lifshitz free energy theory for surface freezing of methane gas hydrates near the freezing point of water. The theory enables us to explore different pathways, resulting in anomalous (stabilising) ice layers on methane hydrate surfaces via energy minimization. Notably, we will contrast the gas hydrate material properties, under which thin ice films can form in water vapor, with those required in the presence of liquid water. It is predicted that methane hydrates in water vapor near the freezing point of water nucleate ice films but not water films.
Nuclear quantum effects lead to an anomalous shift of the volume of hexagonal ice; heavy ice has a larger volume than light ice. This anomaly in ice increases with temperature and persists in liquid water up to the boiling point. We study nuclear quantum effects on the density and compressibility of several ice-like structures and crystalline ice phases. By calculating the anisotropic contributions to the stain tensor, we analyze how the compressibility changes along different directions in hexagonal ice, and find that hexagonal ice is softer along the x-y plane than the z-direction. Furthermo…
Adsorbed layers of water are ubiquitously present at surfaces and fill in microscopic pores, playing a central role in many phenomena in such diverse fields as materials science, geology, biology, tribology, nanotechnology. Despite such importance, the crystal structure of nanoconfined water remains largely unknown. Here we report high-resolution electron microscopy of mono- and few- layers of water confined between two graphene sheets, an archetypal example of hydrophobic confinement. Confined water is found to form square ice at room temperature - a phase with symmetry principally different …
Determining the electronic and dielectric properties of water at high pressure and temperature is an essential prerequisite to understand the physical and chemical properties of aqueous environments under supercritical conditions, e.g. in the Earth interior. However optical measurements of compressed ice and water remain challenging and it has been common practice to assume that their band gap is inversely correlated to the measured refractive index, consistent with observations reported for hundreds of materials. Here we report ab initio molecular dynamics and electronic structure calculation…
With numerical simulations of the mW model of water, we investigate the energetic stability of crystalline clusters for both Ice I (cubic and hexagonal ice) and for the metastable Ice 0 phase as a function of the cluster size. Under a large variety of forming conditions, we find that the most stable cluster changes as a function of size: at small sizes the Ice 0 phase produces the most stable clusters, while at large sizes there is a crossover to Ice I clusters. We further investigate the growth of crystalline clusters with the seeding technique and study the growth patterns of different cryst…
When an ice crystal is born from liquid water two key changes occur: (i) the molecules order; and (ii) the mobility of the molecules drops as they adopt their lattice positions. Most research on ice nucleation (and crystallization in general) has focused on understanding the former with less attention paid to the latter. However, supercooled water exhibits fascinating and complex dynamical behavior, most notably dynamical heterogeneity (DH), a phenomenon where spatially separated domains of relatively mobile and immobile particles coexist. Strikingly, the microscopic connection between the DH …
The study of atmospheric ice nuclei is vital for understanding the formation of precipitation and the development of cloud systems as it reveals how these tiny particles grow. A mechanism of such growth when the nuclei are in a mixed ice/water phase and quantum vacuum fluctuation-induced Casimir-Lifshitz interaction highlights the complexity and interconnection of the atmospheric processes with quantum theory. Initially of the order of $0.1\sim10\rmμm$ in size, atmospheric ice nuclei can expand by the accumulation of water molecules from the surrounding water vapor.
We study the phase equilibrium between liquid water and ice Ih modeled by the TIP4P/Ice interatomic potential using enhanced sampling molecular dynamics simulations. Our approach is based on the calculation of ice Ih-liquid free energy differences from simulations that visit reversibly both phases. The reversible interconversion is achieved by introducing a static bias potential as a function of an order parameter. The order parameter was tailored to crystallize the hexagonal diamond structure of oxygen in ice Ih. We analyze the effect of the system size on the ice Ih-liquid free energy differ…
The interfacial behaviour of water remains a central question to fields as diverse as protein folding, friction and ice formation[1,2]. While the structural and dynamical properties of water at interfaces differ strongly from those in the bulk, major gaps in our knowledge at the molecular level still prevent us from understanding these ubiquitous chemical processes. Information concerning the microscopic motion of water comes mostly from computational simulation[3,4] but the dynamics of molecules, on the atomic scale, is largely unexplored by experiment. Here we present experimental results co…
