A new Janus mesh membrane with ultrafast directional water transportation and improved fog collection

Fog collection materials have been intensively investigated and can potentially be used to alleviate freshwater shortages. However, developing highly efficient fog collection materials remains challenging. Requisite improvements in fog collection technology are the ultrafast transportation of captured water and the effective regeneration of fresh regions on the surfaces of fog collection materials. Herein, a novel Janus mesh membrane (JMM) with an alternating hydrophobic–superhydrophilic-patterned hydrophobic surface and asymmetric wettability interface is prepared by a selective liquid-phase surface oxidation strategy. The unique structure and high-contrast wettability of the JMM enabled ultrafast directional transportation of tiny water droplets (< 0.1 μL), thereby achieving an excellent water collection efficiency of 15.28 g h−1 cm−2, which is much higher than those of conventional Janus membranes. The JMM functioned as a versatile fog collector and maintained continuous fog collection regardless of the fog flow direction. This study offers a novel approach for preparing innovative fog collection materials and establishes a foundation for developing advanced fog collection systems suitable for diverse applications.