Ion Hydration under Nanoscale Confinement: Dimensionality and Scale Effects

How ions are hydrated in nanoconfined spaces is crucial for understanding many natural phenomena and practical applications, such as biological functionalities and energy conversion devices. In real systems, nanoconfinement shows structural diversity, but the influence of dimensionality and scale on ion hydration remains considerably unrevealed. Here, we study ion hydration under various confinements by systematic molecular dynamics simulations. In a given dimension, the structure and dynamics of water molecules in the first hydration shell are altered to a degree inversely correlated with the confinement scale, as long as there is no central bulk-like region. Further comparison of ion hydration among different dimensional systems shows that this scale effect becomes more pronounced in systems with lower dimensionality, due to a more significant water layering effect and lower probability for ions to stay away from confining surfaces. These findings provide a qualitatively new understanding of ion transport in biological channels and are instrumental for the design of functional nanofluidic devices.

Automated summary

The hydration of ions in nanoconfined spaces is influenced by the dimensionality and scale of the confinement. Lower dimensionality leads to a greater impact on ion hydration due to water layering effects and reduced probability of ions staying away from confining surfaces. These findings are significant for understanding ion transport in biological channels and designing functional nanofluidic devices.