A combination structure of microblock and nanohair fabricated by chemical etching for excellent water repellency and icephobicity

Icephobic/anti-icing materials have received growing attentions due to their great potential in reducing energy consumption. The aim of this presented work is to propose a superhydrophobic surface with microblock-nanohair hierarchical structures, and verify its water repellence and icephobic capacity. The hierarchical structures were fabricated by means of a combined method of electrochemical etching and hydrothermal treatment. Following this, the fluoridation modification was performed to obtain the superhydrophobicity with the water contact angle reaching 164° and the sliding angle of 1.5°. The dynamic droplet impacting on the hierarchical structure surface can rapidly rebounce off with the shorter contact time of 9.8 ms, displaying the robust dynamic water repellency. Comparing with the untreated substrate, the resultant superhydrophobic surface exhibited higher anti-icing property with the freezing time of a 4 μL reference droplet increasing from 11.3 s to ∼1700 s at −10 °C, and the ice adhesion force reducing to ∼35 kPa. Furthermore, the comparative studies with the other single-tier structure (i.e., microblock and nanohair structure) surfaces provided the necessary assistance to reveal the underlying action mechanism that the hierarchical micro-nanostructure induced more air pockets underneath droplets to produce the higher hydrophobicity and icephobic capacity.