Wettability gradient of photoresponsive electrospun yarns for harp-based fog water harvesting

Abstract

Fog water harvesting offers a solution to water scarcity. Here, we introduce a method to enhance fog water harvesting systems utilizing electrospun yarns featuring a wettability gradient. These yarns, made from polyvinylidene fluoride (PVDF) and titanium dioxide (TiO2), gain photoinduced hydrophilicity under UV light due to TiO2 photocatalytic properties, allowing dynamic shifts from hydrophobic to hydrophilic states. Experiments show that an alternating PVDF-TiO2 harp with a wettability gradient surpasses purely hydrophobic or hydrophilic versions in fog collection. The strategic mix of hydrophobic and hydrophilic sections enhances droplet movement and water capture, achieving a 16% increase in collection rate up to 400 mg cm−2 h−1. This approach introduces a novel method for creating wettability gradients in electrospun yarns via UV irradiation and represents a significant advancement in adaptable fog water harvesting systems.