Enhanced condensation on multihole-decorated slippery surfaces.

HYPOTHESIS: Efficient dropwise condensation is vital for water harvesting, heat transfer, and other applications. For all of these, it is essential to design surfaces that promote rapid droplet growth and enable quick shedding, such as structured superhydrophobic and slippery surfaces. However, conventional methods rely on precisely engineered micro/nanostructures, which limits their large-scale fabrication and practical applications. Drawing inspiration from the spatial limiting effect of leaf stomata and the slippery surface of the Nepenthes pitcher plant, it should be possible to achieve enhanced condensation on multihole-decorated slippery surfaces.

EXPERIMENTS: Multihole-decorated slippery surfaces were fabricated on aluminum alloys by laser drilling, boiling water etching, low-surface-energy treatment and oil immersion in turn. The condensation dynamics on the flat slippery surface and multihole-decorated slippery surfaces were systematically compared. Further, a water collection experiment was conducted to demonstrate the advantage of multihole-decorated slippery surfaces in enhancing condensation.

FINDINGS: The microholes create an energy barrier between the flat surface and hole regions, guiding droplets toward neighbors to promote coalescence. The slippery interface facilitates droplet departure. This design increases departure frequency by 1.6 times compared to flat slippery surfaces. Consequently，the multihole-decorated slippery surface increases the water collection rate and the heat-transfer coefficient compared the flat slippery surface. This fundamental understanding and design approach are applicable to various water harvesting and phase-change heat transfer applications.