posted on 2022-10-10, 21:05authored byRong Liu, Zhengui Zhou, Xiwei Mo, Pei Liu, Bin Hu, Jiangjiang Duan, Jun Zhou
Passive daytime radiative cooling,
which reflects sunlight
and
simultaneously emits heat into space to cool surfaces without energy
input, is a promising strategy for energy conservation. Integrating
radiative cooling with building systems can tremendously alleviate
electrical cooling, but manufacturing high-efficient and eco-friendly
coatings remains an urgent and challenging task. Here, we present
a simple and scale-up strategy for fabricating ultrawhite coatings
consisting of porous ethyl cellulose matrix–random BaSO4 nanoparticles utilizing green solvents. With the synergistic
effect of the ideal intrinsic properties of the materials and the
strong Mie scattering of the porous structure, the ultrawhite coating
possesses a record solar reflectance of 98.6% and a thermal emittance
of 98.1%, resulting in a subambient temperature drop of over 2.5 °C
under a solar intensity of ∼920 W m–2. Better
yet, our coatings can be conveniently brushed, rolled, or sprayed
onto various types of substrates, with excellent durability, self-cleaning,
and cost-effectiveness, paving an attractive and viable pathway for
large-scale applications in practical buildings.