Green-Manufactured and Recyclable Coatings for Subambient Daytime Radiative Cooling

Abstract

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 BaSO 4 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.

Corrosion-Resistant Hydrophobic Thermal Barrier Composite Coating on Metal Strip: A New Dimension to Steel Strips for Roofing Segment

“…In this study, the solar reflectance characteristics were not studied; the focus was on developing a coating having low thermal conductivity and using a thick coating. Comparing the temperature drop in this report with the previous studies [12][13][14][15]19 indicates that the use of hollow spheres does not always give a higher-temperature drop; probably, their distribution in the coating and inherent thermal conductivity is important.…”

Ag Nanoparticles-Coated Shish-Kebab Superstructure Film for Wearable Heater

“…The distribution of SKF skewer diameters, as depicted in Figure S2a, indicates that they range from 0.5 to 1 μm, with a majority falling within the range of 0.65 to 0.85 μm, which can strongly scatter visible light. 9 From Figure 2b,c, it is apparent that the PDA and AgNPs have dispersed over the surface of the SKF and joined into a network. The experimental results depicted in Figure 2d demonstrate that AgNPs with a diameter of 50 nm are attached to PDA with a diameter of 300 nm, which proves the feasibility of PDA as a binder to modify ASKF films.…”

“…The SKF was fabricated according to our previous work. 9 The modified SKF was prepared using the following procedure. Initially, the polydopamine-shishkebab superstructure films (PSKF) were obtained by immersing the SKF in a dopamine solution at room temperature for 6 h. The dopamine solution was prepared by dissolving 0.12 g of Tris powder and 0.2 g of dopamine hydrochloride in deionized water.…”

“…Polyethylene is frequently utilized in the manufacturing of cooling materials due to its excellent infrared transmission qualities. 9,26−30 In our previous work, 9 we prepared a shishkebab superstructure film (SKF), which, due to the specificity of the structure, has an extremely strong scattering effect on visible light, giving SKFs the ability to provide passive radiative cooling. In order to expand the functionality of SKF, a series of modifications were made, hoping that it could be used as an all-weather heating and thermal management material.…”

Recent progress in organic-based radiative cooling materials: fabrication methods and thermal management properties

“…7c) have 98.6% solar reflectivity and 98.1% thermal emission. 94 In addition, the low UV absorption and fire resistance of 2D hexagonal boron nitride (h-BN, bandgap = 5.96 eV) can be a desirable feature for applications in the building sector. Li et al 95 reported a method for introducing h-BN dielectric nanoplates into PDMS to prepare a scalable photonic film.…”