Brilliant colorful daytime radiative cooling coating mimicking scarab beetle

Passive daytime radiative cooling is regarded as a promising technology to achieve all-day subambient cooling without energy consumption and pollution. The installation of monotonous white radiative cooling coating on the facades of buildings poses challenges in terms of aesthetic integration. Fabricating radiative cooling coatings with different colors and high cooling efficiency at a low cost is an optimal solution for their broad adoption and commercialization. Here, inspired by the elytra of the scarab beetle, we design a hierarchically porous nested structured radiative cooling film with high subambient cooling efficiency and flexible color tunability. This film exhibits both high solar reflectance (93.4%) and superior thermal emissivity (92.3%), realizing subambient cooling of ∼10.2°C at night and ∼7.2°C at midday. Its color is brilliant, stable, and flexible. Additionally, this film is self-cleaning and can reduce noise, which suggests possibilities for the development of multifunctional radiative cooling surfaces in building envelopes, automobile coatings, and clothes.