Molecular Dynamics for Nanoconfined Ion and Water Transport: Mechanisms and Applications in Functional Nanofluidic Devices

Water and ion transport in nanoconfined spaces exhibits a range of anomalous phenomena, such as spontaneous water filling, dielectrophoretic compression, ultrafast flow, ion selectivity, ionic rectification, and memristive behavior, that differ fundamentally from classical macroscale transport. These transport phenomena underpin emerging applications in advanced desalination membranes, high-sensitivity nanofluidic sensors, and bioinspired neuromorphic devices. A comprehensive understanding of these transport mechanisms is critical for the rational design and optimization of nanofluidic systems for real-world applications in water purification, biosensing, and nanofluidic iontronics. While experimental techniques struggle to resolve the real-time dynamics of molecular and ionic transport in nanometer and subnanometer channels, molecular dynamics (MD) simulations provide atomistic insights by tracking atomic motions on the femtosecond time scale. This enables the detailed exploration of structural, energetic, and kinetic mechanisms that are otherwise inaccessible to experiments. This Review presents a comprehensive overview of recent advances in MD-based investigations of nanoconfined ion and water transport. It highlights how simulation-driven understanding of confinement effects, interfacial interactions, and external field modulation provides a foundation for the rational design of functional nanofluidic devices. The goal is to bridge fundamental transport mechanisms with practical applications in ion-selective membranes, ionic transistors, and bioinspired iontronic systems.