Nanochannel‐Based Ion Transport and Its Application in Osmotic Energy Conversion: A Critical Review

Abstract

Nanochannel‐based ion transport is an important field of study in various disciplines, including physics, chemistry, energy, materials science, biology, and earth science. The unique features of natural nanochannels have inspired numerous innovative designs that seek to achieve high ion permeability, selectivity, and rectification. A notable example is osmotic energy conversion, which harvests sustainable salinity‐gradient energy to generate electricity without moving parts, noise, or carbon emissions and thus serves as a promising alternative to traditional fossil fuel utilization. This review focuses on the fundamental principles, regulatory methods, and practical applications of nanochannel‐based ion transport for osmotic energy conversion. The physical mechanisms of ion transport and the intriguing phenomena of ion behaviors in nanoconfined spaces are discussed first, followed by a thorough examination of the overall process of osmotic power generation from mathematical, numerical, parametric, first‐principles, molecular simulation, and modeling perspectives. Strategies for enhancing the osmotic performance are then discussed to overcome the trade‐off between ion selectivity and ion flux, including the theoretical design of nanochannel geometry and electrification, experimental optimization of nanoporous membranes, and electrolyte thermal enhancement. The existing challenges and opportunities for the future development of nanochannel‐based ion transport and osmotic power generation are addressed at the end.