  The scattering of light by resonant nanoparticles is a key process for
enhancing the solar reflectance in daylight radiative cooling. Here, we
investigate the impact of material dispersion on the scattering performance of
popular nanoparticles for radiative cooling applications. We show that, due to
material dispersion, nanoparticles with a qualitatively similar response at
visible frequencies exhibit fundamentally different scattering properties at
infrared frequencies. It is found that dispersive nanoparticles exhibit
suppressed-scattering windows, allowing for selective thermal emission within
an highly reflective sample. The existence of suppressed-scattering windows
solely depends on material dispersion, and they appear pinned to the same
wavelength even in random composite materials and periodic metasurfaces.
Finally, we investigate calcium-silicate-hydrate (CSH), the main phase of
concrete, as an example of a dispersive host, illustrating that the co-design
of nanoparticles and host allows for tuning of the suppressed-scattering
windows. Our results indicate that controlled nanoporosities would enable
concrete with daylight passive radiative cooling capabilities.
