Nanocomposite coatings with plasmonic structural colors for subambient daytime radiative cooling

Daytime radiative cooling is an innovative passive cooling technology to realize energy saving and counter global warming. To fulfill the demand for aesthetic appearance and effective display in real-life situations, coloration should be incorporated with daytime radiative cooling. Moreover, all of the reported subambient daytime colorful radiative coolers rely on the metal layered reflector, which prevents them from many applications. In this work, we propose a series of colorful radiative cooling coatings consisting of metallic nanoparticles (plain Ag and TiO2@Ag core–shell nanoparticles) for coloration, Y2O3 submicron particles with 30% volume fraction for solar radiation reflection, and polymethyl methacrylate resin as the matrix. A theoretical model on radiative properties of these cooling coatings is proposed by considering the dependent scattering effects among Y2O3 scatterers and localized surface plasmon resonance of metallic nanoparticles. Afterwards, we conduct a parametric study on the coloration and cooling performance of these coatings with different volume fractions and size distributions of embedded particles. Based on numerical simulations, we show these coatings can present a variety of colors and realize temperature drops of 2.0–3.9 °C and net cooling power of 23–47 W/m2 at a total metallic nanoparticles volume fraction of 0.0002%. This work provides pathway for large-scale-manufacturable colorful radiative cooling coatings with potential applications in eco-friendly buildings and outdoor facilities.