Bridging Hydration-Shell Exchange Kinetics and Ion Translocation Energy Barriers across Graphene Nanopores

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Abstract
Ion transport across angstrom-scale graphene nanopores is governed by hydration-shell dynamics, yet the kinetic origin of the associated translocation energy barrier remains unresolved. Here, we bridge hydration-shell exchange kinetics and ion translocation energy barriers by resolving water residence events during pore crossing. Ionic conductance measurements establish the angstrom-scale confinement regime of graphene nanopores, within which molecular dynamics simulations are employed to analyze hydration-shell dynamics. We implement a residence-time analysis that decomposes hydration-shell water behavior into confinement-induced dehydration, regular water exchange, and thermal fluctuations. This analysis enables a quantitative determination of the number of hydration waters irreversibly removed during translocation. For both K+ and Mg2+, the extent of irreversible dehydration increases monotonically with the translocation energy barrier. These results identify hydration-shell exchange kinetics as the molecular-level determinant of ion transport barriers, providing a dynamically grounded and physically transparent picture of ionic transport under extreme nanoconfinement.
Funding Information
  • Fundamental Research Funds for the Central Universities (WK2090000087)
  • National Natural Science Foundation of China (12241203)
  • National Natural Science Foundation of China (12474026)
  • Natural Science Foundation of Guangdong Province (2025A1515011749)
  • Scientific Research Innovation Capability Support Project for Young Faculty (SRICSPYF-ZY2025050)

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