Cellulose-based electrospun membranes with tuning wettability and flow-guiding structure for enhanced passive fog harvesting

Global freshwater scarcity has intensified interest in passive fog harvesting as a low-energy strategy for decentralized water supply. However, most existing fog-harvesting systems rely on complex structures or extreme wettability gradients, making it difficult to simultaneously optimize droplet capture, growth, and removal. Herein, a synergistic strategy combining wettability regulation and flow-guiding structures is proposed for efficient fog harvesting. Electrospun cellulose acetate nanofibrous membranes were subjected to controllable alkaline deacetylation to regulate surface wettability. Appropriate hydrophilicity promoted droplet nucleation, adhesion, and sustained growth. The membrane treated for 2 h (DCA2 NFM) exhibited balanced wettability and increased the fog collection rate from 1.481 to 2.519 g·cm −2 ·h −1 . Furthermore, parallel copper wire arrays were introduced to construct low-resistance drainage pathways, accelerating gravity-driven droplet transport and surface renewal. As a result, the optimized membrane achieved a fog collection rate of 3.996 g·cm −2 ·h −1 . This work provides a simple and scalable strategy for coordinating droplet capture and drainage in passive fog harvesting.