Superhydrophobic and Abrasion-Resistant Coatings for Above-Ambient Passive Daytime Radiative Cooling via the Scalable Spraying Process

Passive daytime radiative cooling (PDRC) offers an energy-free cooling strategy by reflecting solar radiation and emitting thermal radiation through an atmospheric window. However, existing PDRC materials face challenges, such as contamination, mechanical damage, and durability issues. Herein, a superhydrophobic and abrasion-resistant PDRC coating is developed using a fluorinated acrylic polymer matrix with SiO2 and TiO2 nanoparticles, fabricated via a simple one-step spraying process. By regulating the content of different components, the optimal coating achieves high solar reflectivity (91.1%) and atmospheric window emissivity (93.7%) and has a superhydrophobicity of 157°, preventing dust and water adhesion. The coating maintains excellent durability and optical performance after 3000 abrasion cycles under a 250 g load. The coating can also be processed into colored variants without compromising its high reflectivity and emissivity. Moreover, it demonstrates excellent above-ambient cooling performance at daytime and achieves a temperature reduction of 1.8 °C at daytime and 1.7 °C at nighttime compared with the commercial coating. These results highlight a scalable and cost-effective solution for sustainable cooling applications.