Dual-path suppression of thermal and wetting-driven steel corrosion for marine structure

nanoparticles enhance solar reflectance (94.6%) and mid-infrared emittance (92.8%), enabling efficient passive cooling. Integrated with the hydrophobic overlayer for waterproofing, this protective bi-coating achieves a sub-ambient cooling (4.13 °C) under direct sunlight and excellent anti-wetting property (water contact angle of 151.3°), effectively mitigating solar thermal loading and chloride penetration. Furthermore, after 30 days of cyclic solar illumination-salt spray exposure, the protective layer can significantly reduce corrosion initiation time and current density, demonstrating double-effect protection for reinforced concrete through ion-blocking and cooling-enabled corrosion buffering. This work pioneers a passive strategy that synergizes radiative cooling, chemical compatibility, and ion-blocking functionality to extend the service life of marine infrastructure under coupled thermo-chemo degradation.