Water collecting carbon nanotube yarn with biomimetic composition and structure

The unique features of chemical composition and surface roughness in biological systems, such as spider capture silk and cactus, enable them with excellent water retention characteristics. Inspired by biological designs, this work developed a living fog collecting yarn with excellent water retention and collection capacity by using carbon nanotube yarn (CNTY) and ionic silk fibroin glue (ISFG) as starting materials. Through dip-coating, a glycoprotein-like ISFG was attached to CNT yarn for capturing water molecules from the surrounding foggy environment. Using the yarn-twisting technique, the cactus spine-like microgroove structure was created on the surface of CNT yarn, which provided the driving forces for the directional movement of water droplets. The chemical and structural synergetic effects allow the fog-collecting CNTY to absorb the fog, gather water, and directionally transmit the droplets to the ends of yarn. These merits of fog-collecting CNTY for water absorption capacity (0.33 mg cm−1) and fog collecting rate (29.8 mg cm−1 within 420 s) make them promising tools for water collection in the arid environment and sewage purification in polluted conditions. In addition, the theoretical structure-function relation of this bioinspired fog-collecting CNTY was also elaborated to guide the design of performance-optimized fog collecting fibers.