Molecular Insights into the Effect of Nanoscale Surface Roughness on CO2 Hydrate Nucleation: Implications for Carbon...

Hydrate-based CO2 sequestration is a promising carbon storage technology, but its practical application is hindered by slow formation kinetics. Understanding the nucleation mechanism at a molecular level is crucial for optimizing this process. Herein, systematic microsecond molecular dynamics simulations are employed to investigate the effect of nanoscale surface roughness on CO2 hydrate nucleation. These results indicate that nanoscale surface roughness acts as a kinetic promoter for CO2 hydrate nucleation. A clear inverse relationship between the degree of nanoscale surface roughness and the induction time is observed, with the most topographically complex surface reducing the nucleation induction time by over 60% compared to a perfectly smooth surface. The underlying molecular mechanism operates via an indirect kinetic promotion pathway where the rough topographies disrupt the stable accumulation of gas films on the substrate. By geometrically hindering dense CO2 surface packing, the nanoscale corrugations accelerate gas dissolution into the bulk aqueous phase, establishing higher early-stage supersaturation levels that lower the barrier for clathrate cage crystallization. Concurrently, the topographical corrugations restrict dense gas film formation and modulate interfacial fluid dynamics, facilitating rapid gas transfer into the aqueous domain and driving clathrate crystallization near the bubble boundary. These molecular insights further broaden the understanding of hydrate-based CO2 sequestration, especially in reservoir engineering or the selection of suitable CO2 sequestration sites.