Waxberry-liked micro-nanostructured, superhydrophobic surfaces with enhanced photothermal de-icing and passive anti-icing properties

Superhydrophobic surfaces (SHSs), as one of the most promising passive anti-icing materials, suffer from unavoidable icing under high-humidity cool environment. Photothermal de-icing capability with robust light absorption feature is thereby necessitated to integrate into SHSs to ensure maximum icephobic performance. Herein, a facile strategy of using polyurethane and synthesized waxberry-liked Co3O4 nanoparticles (WCNPs) to construct hierarchical micro-nanostructured composites exhibiting superhydrophobic, photothermal and "lighttrapping" properties is proposed. WCNPs self-assemble from nanoscale spheres, inherently possessing a hierarchical micro-nano structure. Sophisticated surface structure created by abundant WCNPs with unique intrinsic hierarchical morphology provides the composites with both excellent water repellency and impressive "lighttrapping" capability of 92.7 % light absorptivity. Besides, WCNPs are covered by self-polymerized tannic acid layer interconnected with octadecylamine, which further facilitates the hydrophobic properties. In highhumidity (95 %) environments at -10 degrees C, ice delay time can be enhanced to 802 s, while the melting time under 1 sun irradiation for ice crystal and layer are only 156 s and 370 s, respectively. Furthermore, reliabilities of the coating are verified by comprehensive durability assessments, including wear resistance, adhesion and icing/deicing cycle tests. This study constructs a surface micro-nano layer structure to absorb the abundant solar energy in nature and transform it into heat, providing a promising solution in anti-icing and de-icing fields.