A Skin‐Effect and Ion‐Pumping Inspired 3D Solar Evaporator With High Salt Resistance for Sustainable Desalination

ABSTRACT Solar‐driven interfacial evaporation holds promise for addressing freshwater scarcity, yet its long‐term performance is compromised by salt fouling. Herein, we present a 3D dispersed interfacial evaporator that synergistically integrates the “skin effect” and “ion‐pumping effect” to enhance vapor generation and salt resistance. The evaporator was prepared by deposition of a chemically crosslinked polyvinyl alcohol/clay composite hydrogel onto polyester aroma sticks to improve hydrophilicity and stabilize capillary channels, and then deposition of Cu‐MOF nanocrystals to provide broad‐spectrum light absorption (>90%). Under 1 kW m −2 illumination, the evaporator achieved average evaporation rates of 4.68 and 4.36 kg m −2 h −1 during 10 h of continuous operation in 3.5 wt.% and 20 wt.% NaCl solutions, respectively. Further structural optimization using ambient wind flow boosts the evaporation rate to 15.82 kg m −2 h −1 at a wind speed of 1 m s −1 . Mechanistic investigations reveal the skin effect mitigates structural degradation by restricting salt crystallization to surface layers, while the ion‐pumping effect promotes ion diffusion to prevent salt accumulation. Outdoor tests verify that ion concentrations in the harvested freshwater comply with the WHO drinking water standards. This study demonstrates a viable strategy for robust, high‐efficiency, salt‐tolerant solar desalination under diverse environmental conditions.