Synergistic Photothermal and Superhydrophobic Metasurface for Passive Radiative Cooling and Anti‐/Deicing

ABSTRACT Passive radiative cooling offers a sustainable pathway for building thermal regulation without energy input, however, the sub‐ambient surface temperatures inevitably promote ice nucleation and accretion in cold climates, creating a fundamental seasonal conflict. In this work, we address this seasonal limitation by hierarchically engineering a synergistic photothermal and superhydrophobic metasurface (SFPS film) that delivers efficient radiative cooling in summer while enabling anti‐icing and de‐icing in winter. The SFPS film integrates self‐assembled hollow glass bead/nano‐SiO 2 supraballs for Mie scattering, a PDMS matrix with pyramidal microstructures for emissivity enhancement, and SiO 2 @Fe 3 O 4 nanospheres with superhydrophobic coating for photothermal conversion and water repellency. The SFPS film exhibits a solar reflectivity of 88%, which is lower than the 97% of the Pyramid‑PDMS/Supraballs film due to absorption by the SiO 2 @Fe 3 O 4 , while maintaining an atmospheric window emissivity of 96%, enabling sub‑ambient cooling of 4°C–6°C under outdoor summer conditions. In winter, the durable superhydrophobic surface together with the photothermal effect synergistically delays freezing by a factor of 4.6 and cuts melting time by 51% compared to bare glass, while also reducing ice adhesion strength to ∼25 kPa. This multifunctional metasurface offers a promising pathway toward all‐season passive thermal management for buildings, transportation, and outdoor infrastructure.