Mass Transport Mechanisms in 2D Laminar Nanofluidic Membranes for Separation and Energy Conversion

Two‐dimensional (2D) lamellar structures have attracted significant attention due to their scalability and tunability, enabling versatile applications such as ion separation, water purification and osmotic energy conversion. This review discusses the mass transport mechanisms in 2D laminate membranes that govern selectivity and permeation in osmotic energy applications. We discuss how membrane structure, transport pathways, concentration gradients and medium pH influence ionic and molecular transport and identify key factors for sustainable separations. Furthermore, we highlight recent strategies to tailor nanofluidic performance and overcome the selectivity–permeability trade‐off, including cation intercalation, functional group incorporation and stimulus‐responsive polymer integration. We then relate these improvements to the underlying mass‐transport behaviour and highlight emerging applications in osmotic energy harvesting, desalination and lithium‐ion selective separation. This review provides an outlook that guides the development of 2D nanofluidic membranes for energy technologies.