Rapid and Persistent Suction Condensation on Hydrophilic Surfaces for High-Efficiency Water Collection

Water
collection by dew condensation emerges as a sustainable solution
to water scarcity. However, the transient condensation process that
involves droplet nucleation, growth, and transport imposes conflicting
requirements on surface properties. It is challenging to satisfy all
benefits for different condensation stages simultaneously. By mimicking
the structures and functions of moss Rhacocarpus,
here, we report the attainment of dropwise condensation for efficient
water collection even on a hydrophilic surface gated by a liquid suction
mechanism. The Rhacocarpus-inspired porous surface
(RIPS), which possesses a three-level wettability gradient, facilitates
a rapid, directional, and persistent droplet suction. Such suction
condensation enables a low nucleation barrier, frequent surface refreshing,
and well-defined maximum droplet shedding radius simultaneously. Thus,
a maximum ∼160% enhancement in water collection performance
compared to the hydrophobic surface is achieved. Our work provides
new insights and a design route for developing engineered materials
for a wide range of water-harvesting and phase-change heat-transfer
applications.