3D Hierarchical Water‐Salt Transport Networks for Highly Efficient Solar‐Driven Interfacial Evaporation

Abstract

ABSTRACT Solar‐driven interfacial evaporation (SDIE) offers a sustainable pathway for freshwater production, yet conventional hydrogel evaporators are hindered by high pore tortuosity, prolonged diffusion pathways, and interfacial salt accumulation that severely compromise long‐term operational stability. Herein, we report a bilayer fabric‐hydrogel composite (CPF/PF‐H) that integrates a 3D hierarchical architecture with molecular‐level interfacial engineering to decouple water and salt transport. The design features vertically aligned fabric macrochannels for low‐tortuosity water transport, radially distributed interstitial pores for supplementary water supply, and microporous hydrogel networks for localized salt confinement. Meanwhile, polydopamine (PDA) reinforces interfacial bonding between the fabric framework and the hydrogel matrix, ensuring robust mechanical integrity and structural stability under harsh operating conditions. As a result, the CPF/PF‐H evaporator achieves a good evaporation rate of 2.36 kg m −2 h −1 with high efficiency of 92.76% in water and maintains stable performance in 20 wt% NaCl brine (1.99 kg m −2 h −1 for over 8 h) under 1‐sun irradiation. Additionally, it exhibits excellent cycling stability across varying salinities (3.5–20 wt%) and pH (3–11). This work establishes a universal strategy for designing scalable, high‐efficiency hydrogel‐based SDIE systems through synergistic materials architecture and interfacial engineering, offering a practical pathway toward sustainable desalination.