Beyond Micro‐/Nanostructures: Close‐Packed Nanostructure Enables Superior Superhydrophobic Anti‐Icing Coatings

ABSTRACT Hierarchical micro‐/nanostructures have long been regarded as the optimal architecture for superhydrophobic anti‐icing surfaces. Here, by constructing superhydrophobic coatings with identical surface chemistry but distinct microscopic architectures, we directly compare the anti‐icing performance of a close‐packed nanostructure and a hierarchical micro‐/nanostructure. Surprisingly, the close‐packed nanostructure consistently outperforms its hierarchical counterpart in static/dynamic superhydrophobicity at room temperature and icing environments, freezing delay, ice adhesion reduction, and freeze/de‐icing cycling stability, etc. Mechanistic investigations reveal that the close‐packed nanostructure generates a higher Laplace‐pressure barrier against water penetration, suppresses contact‐line pinning, and minimizes interfacial energy dissipation during droplet impact. In contrast, micro‐grooves within the hierarchical micro‐/nanostructure act as preferential pathways for water infiltration, promoting Cassie‐to‐Wenzel transitions and interfacial adhesion in icing environments. Moreover, the nanostructured coating maintains robust superhydrophobicity and low ice adhesion after mechanical abrasion, tape‐peeling and long‐term outdoor exposure, etc. These findings challenge the long‐standing “hierarchical‐is‐better” paradigm and identify the close‐packed nanostructure as a more effective structural strategy for durable superhydrophobic anti‐icing surfaces, providing new design guidelines for next‐generation passive icephobic materials.