Photothermal‐Enhanced Ion Transport in Robust 2D Hybrid Nanofluidic Membranes for Osmotic Energy Conversion

Abstract Multifunctional 2D membranes with interstitial nanofluidic channels are of great significance for controllable ion transport and osmotic energy conversion. Herein, the robust photothermal‐responsive 2D hybrid membranes based on the near‐parallel laminar stacking of black phosphorus (BP) and montmorillonite (MMT) nanosheets reinforced by cellulose nanofibers (CNF) are developed. The resultant hybrid membrane exhibits cationic selectivity and surface‐charge‐governed ion transport properties. The photothermal effect of BP nanosheets increases the surface temperature of the hybrid membrane under illumination, which contributes to enhanced ion transport. This photothermal‐enhanced ion transport boosts the maximum power density of osmotic energy conversion from 4.84 to 5.31 W·m⁻² by 9.7% at a 50‐fold concentration gradient under 400 mW·cm⁻² simulated sunlight. This work reveals the integration of the photothermal effect of BP nanosheets in 2D nanofluidic membranes, providing a possible route to enhance the osmotic energy conversion performance by renewable light energy.