Advances in molecular dynamics simulation on heterogeneous nucleation of gas hydrate

Gas hydrate is a nonstoichiometric crystalline material. It is attracting more and more attention not only because natural gas hydrate is a potential energy resource, but also because hydrate-based technologies can be potentially applied to the industry of energy and environment such as energy storage, carbon sequestration, etc. The nucleation mechanism of gas hydrate is a key issue in studying reservoir formation of natural gas hydrate and the kinetic properties of gas hydrate as an energy-storage media. Molecular dynamics simulation can provide microscopic insights into molecular-scale understanding of hydrate nucleation. In this review, the advances on the study of heterogeneous hydrate nucleation by molecular dynamics simulation are summarized, with a specific focus on the factors affecting nucleation processes. The interfacial energy barrier for nucleation will be lowered by molecular structure of interfacial water between hydrate and solid substrate. The interface and surface properties of solid substrate, including hydrophilicity and hydrophobicity, surface roughness, layer-accumulated adsorption potential, crystallinity and surface layer-charge are also recognized as being associated with the process of hydrate nucleation by influencing the dynamics of gas and water molecules. In case of hydrate nucleation in confined pore space, confinement effect, pore size and elasticity are identified as the controlling factors.