Hierarchical surfaces that aid in the droplet nucleation, growth, and removal is highly
desirable for fog and moisture harvesting applications. Taking inspiration from the
unique architecture of leaf skeletons, we present a multiscale surface capable of
rapidly nucleating, growing, and directional transport of the water droplets. Copper
oxide microtufts were fabricated onto the
Ficus religiosa
leaf
skeletons via electroplating and chemical oxidation techniques. The fabricated surfaces
with microtufts had high wettability and very good fog harvesting ability. CuO surfaces
tend to become hydrophobic over time because of the adsorption of the airborne species.
The surfaces were efficient in fog harvesting even when the hydrophobic coating is
present. The overall water collection efficiencies were determined, and the role of the
microtufts, fractal structures, and the orientation of leaf veins was investigated.
Compared to the planar control surfaces, the noncoated and hydrophobic layer-coated
copper oxide microtufts on the leaf skeletons displayed a significant increase in the
fog harvesting efficiency. For superhydrophilic skeleton surfaces, the water collection
rate was also observed to slightly vary with the vein orientation. The CuO microtufts
along with high surface area fractals allowed an effective and sustainable way to
capture and transport water. The study is expected to provide valuable insights into the
design and fabrication of sustainable and efficient fog harvesting systems.