▎ 摘　　要

Understanding and control of the methane hydrate formation are of central importance for applications ranging from natural gas exploitation to transportation. Fabricated carbon nanomaterials, owing to their outstanding physicochemical properties, are increasingly considered as additives to manipulate the hydrate formation, whereas little is known about the underlying molecular mechanism. Here, we investigate the methane hydrate formation in the presence of graphene nanosheets (GNs) using molecular dynamics simulations. Particular attention is placed on the effects of size, aggregation, and oxidation of GNs. Individual GNs are found to play roles in a size-dependent manner, as sharp corners of GNs are preferentially anchored into cavities at the hydrate surface, exposing other segment in a solvent to disturb the local hydrate structure. Once GNs form aggregates exceeding a critical size, methane molecules can be recruited to promote formation of nanobubbles, thus retarding the hydrate formation due to depletion of methane in the aqueous phase. Graphene oxide forms hydrogen bonds with water both in the aqueous phase and at the hydrate surface, thus reducing the water activity to obstruct the hydrate growth. Our results have important consequences for regulating the methane hydrate formation and open up new avenues for the energy application of graphene family nanomaterials.