Coordinating the processes of droplet capture, transport, and shedding during fog harvesting remains a significant challenge. In this study, we prepared a copper mesh with varying wettability through chemical etching and thiol modification. The Cu(OH)2 needle structures on the surface of the samples were characterized using field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS). Additionally, the surface chemistry of the samples was analyzed using infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). A Janus membrane matchbox fog collector with directional transport properties was designed and assembled, effectively enhancing fog capture efficiency while facilitating the directional transport of fog droplets across a grid. We constructed a fog harvesting test rig in the laboratory and evaluated the samples at a fog flow rate of 0.8 m•s⁻¹. The highest observed fog harvesting efficiency reached 6.9 g•h⁻¹•cm⁻², demonstrating the potential for sustained and efficient fog harvesting even in dynamically changing fog environments. This study introduces a novel Janus membrane material that offers broad applications for developing green, low-cost, and efficient fog harvesting strategies.
