Hybrid wettability surfaces with hydrophobicity and hydrophilicity for fog harvesting

Fog harvesting has gained increasing attention because it can effectively alleviate the shortage of fresh water resources. In this study, a simple atomization-assisted nonsolvent induced phase separation combined with high pressure spraying method was used to fabricate a micro-nano composite porous membrane with hybrid wettability for fog collection. The driving force generated by the surface energy gradient between the superhydrophilic and superhydrophobic regions is beneficial to improve the fog collection efficiency. The fog collection efficiency was found to be dependent on the surface microstructure and the coverage of hydrophobic region, which could be well adjusted by tuning the atomization pretreatment and the high pressure PDMS spraying time. The optimized fog collection efficiency was 46.2 mg·cm−2·min−1 when the atomization pretreatment time was 30 s and the high pressure spraying time was 1 s. The membrane also exhibited excellent structural stability when being used for oil water separation. This work provides a new idea for the preparation of membranes with hybrid wettability surface and their application in the field of fog collection.