Bio-inspired Nanoarchitectonics of Re-entrant Geometries Toward Transparent Omniphobic Surfaces

Omniphobic coatings provide liquid repellent surfaces by trapping air in their micro nanostructured surfaces and show promise for various applications. However, it remains a formidable challenge to fabricate such coatings in a controllable way. Here, we report facile construction of a series of re-entrant geometries that resemble the skin of springtails. By rationally controlling the parameters of dip-coating operation assisted by a colloidal crystal template, three elaborate structures in the morphology of re-entrant triangular posts, concave quadrilateral posts, and circular holes have been constructed. These nanostructured surfaces exhibit excellent omniphobicity that repel liquids with a wide spectrum of polarity. Impressively, the honeycomb porous re-entrant structures also demonstrate exceptionally high light-harvesting performance derived from their excellent scattering ability. Through this proof of concept, our simple, controllable, and scalable method shows great potential in designing highly efficient omniphobic surfaces for practical solar energy applications.