The ability to manipulate the flux of ions across membranes is a key aspect of diverse sectors including water desalination, blood ion monitoring, purification, electrochemical energy conversion and storage. Here we illustrate the potential of using daily changes in environmental humidity as a continuous driving force for generating selective ion flux. Specifically, self-assembled membranes featuring channels composed of polycation clusters are sandwiched between two layers of ionic liquids. One ionic liquid layer is kept isolated from the ambient air, whereas the other is exposed directly to the environment. When in contact with ambient air, the device showcases its capacity to spontaneously produce ion current, with promising power density. This result stems from the moisture content difference of ionic liquid layers across the membrane caused by the ongoing process of moisture absorption/desorption, which instigates selective transmembrane ion flux. Cation flux across the polycation clusters is greatly inhibited because of intensified charge repulsion. However, anions transport across polycation clusters is amplified. Our research underscores the potential of daily cycling humidity as a reliable energy source to trigger ion current and convert it into electrical current.
Karst regions face severe water scarcity due to rapid hydrological leakage and complex geological structures. To address this challenge, this study developed a bioinspired porous condensation material by integrating sand-based substrates with optimized hydrophilic-hydrophobic properties and aluminum fiber modifications. Through orthogonal experiments, the optimal formulation (0.3 mL 30 % H 2 O 2 , 3.4 mL water, 0.4 g foam stabilizer) achieved a high porosity of ∼58 % and uniform pore distribution (Féret diameter: 0.83 mm), enabling a water collection rate of 0.066–0.068 g g −1 h −1 . Aluminum fiber incorporation (≤4 g, ≤0.1 mm) enhanced thermal diffusivity by 37.5 %, facilitating rapid heat transfer for efficient vapor condensation. In simulated diurnal humidity-temperature cycles, the modified material exhibited dynamic water adsorption-desorption capabilities, with a 140 % improvement in nighttime water retention (0.06 g g −1 ) and 42.3 % higher daily yield compared to unmodified counterparts. The material's pore-thermal synergy, driven by threshold-controlled fiber networks, balanced capillary-driven water transport and heat-mediated condensation, overcoming structural instability under extreme temperature fluctuations. These results demonstrate a cost-effective strategy for designing environment-responsive water-harvesting materials, offering potential applications in arid regions, micro-irrigation systems, and humidity regulation.
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