A water-rich system of constructing durable and fluorine-free superhydrophobic surfaces for oil/water separation

[Display omitted] •Superhydrophobic surface was fabricated with a water-rich system.•The surface has self-cleaning ability due to superhydrophobicity and photocatalysis.•The surface shows efficient oil/water separation and water purification ability. Despite the existing efforts, developing a versatile and less-harmful method is of difficulty for the preparation of durable superhydrophobic surfaces. Herein, a mild and water-rich approach is proposed to obtain fluorine-free robust superhydrophobic materials, which is prepared using composite solutions of polydimethylsiloxane (PDMS) and titanium dioxide (TiO2) to reduce the usage of organic solvents. With the optimized PDMS solution/TiO2 aqueous sol mass ratio (2:8), the coated cotton fabric possessed a water contact angle (WCA) of 156.9° and a shedding angle of 6.8°. The resulting superhydrophobic cotton fabric (SCF) also performed well under various harsh conditions. Furthermore, the SCF not only exhibited excellent anti-staining ability, but also could degrade organic pollutant under UV irradiation owing to its photocatalytic activity. More importantly, the SCF could be used repeatedly for oil-water separation and water purification without significant loss in its superhydrophobicity, which provide the prospect of employing in the field of environmental protection. The composite coating can be utilized on different substrates including PET fabric, non-woven fabric and sponge to impart superhydrophobicity to their surfaces. Overall, our work provides a facile, timesaving and less-harmful approach for fabricating multifunctional superhydrophobic fabrics, which have significant advantages in self-cleaning, outdoors and water treatment application.