Magnetically Driven Cactus Spinelike Superhydrophobic Fe₃O₄ Vertical Array for High-Performance Fog Harvesting

Cactus spinelike materials have attracted much attention due to high fog harvesting efficiency, but great challenges in structure fabrication and structural controllability still remain. In this study, we proposed a magnetically driven spray-coating method to fabricate a cactus spinelike superhydrophobic Fe₃O₄ vertical array on nonwoven cotton fabric. This method is simple and controllable; a mixture containing magnetic Fe₃O₄ particles and organosilicon resin was atomized into tiny droplets and arranged along the magnetic field lines. Different from the traditional method to prepare a cactus spinelike structure via liquid flow under magnet, which is usually accompanied with a big structure size and an unobvious structure feature due to the high viscosity of magnetic liquid. However, if the magnetic liquid is transformed into tiny magnetic droplets by a spraying method, it is promising to prepare micrometer-scale conical structures, and the reduction degree of bionic structures is high. When the fabricated structure is used for fog harvesting, it shows an extremely high efficiency of approximately 6.33 g cm^-2 h^-1, which is superior to most state-of-the-art fog harvesting materials. Considering the advantages of simplicity, structure controllability, and high fog harvesting rate, the reported strategy provides an avenue to build up high-performance fog harvesting materials.