Superhydrophobicity from composite nano/microstructures: Carbon fabrics coated with silica nanoparticles

This study demonstrates the hydrophobic coating of silica nanoparticles onto microscaled carbon fabrics (CFs) and investigates the superhydrophobic behavior of composite nano/microstructures. The two-tier composite surfaces are based on regularly ordered carbon fibers (8–10 µm in diameter) that are coated with SiO2 nanoparticles with an average size of 300–500 nm. The microscale fiber is used here as the primary surface roughness, while the silica nanoparticles serve as the secondary roughness, mimicking the lotus leaf in nature. Increasing the density of silica on CFs showed significant effects on the enhancement of static contact angle, decrease of contact angle hysteresis, and superhydrophobic stability. The results can be attributed to the fact that the higher density of silica coating results in more tortuous three-phase contact line, thus facilitating the self-cleaning effect.