Efficient fog harvesting on metal surfaces with venation-inspired wetting patterns fabricated via laser-based maskless approach

The issue of global freshwater scarcity has become more pressing as climate change effects intensify. Fog harvesting has emerged as a sustainable and promising solution to address this problem, and wettability-patterned surfaces have shown potential in enhancing fog harvesting efficiency. In this study, two venation-like surface wetting patterns, i.e., the broadleaf and coniferous tree patterns, were directly fabricated on an aluminum alloy (AA6061) using a laser-assisted functionalization method, which offers greater flexibility in creating innovative patterns without the need for a mask. The superhydrophobic region featured low-roughness, isotropic, random nanostructures, while the superhydrophilic regions consisted of highly structured porous microchannels. The resulting surface patterns demonstrated a significant increase of up to 100 % in fog harvesting capability compared to the untreated surface. By adjusting the number of leaves, the fog harvesting efficiency of the venation-like patterns can be further improved while maintaining the same energy investment.