In Situ Formation of SiO₂ Nanospheres on Common Fabrics for Broadband Radiative Cooling

Abstract

Radiative cooling materials are attracting more and more attention because of their intrinsic advantages in energy saving and environmental protection, especially radiative cooling fabrics. In this paper, we used tetraethyl orthosilicate (TEOS) as the silicon source and prepared radiative cooling fabrics by in situ synthesizing SiO 2 microspheres on polyester cloth. The in situ formation of SiO 2 microspheres results in strong bonding with polyester fibers, solving the problem of powder peeling. The fabrics we prepared have a high emissivity of more than 95% in the midinfrared band and a relatively high reflectivity of ∼70% in the visible−near infrared band and can realize effective radiative cooling. The cooling effect would vary with the amount of TEOS added, and the sample with the optimal performance could achieve a maximal temperature drop of 11.2 °C under direct sunlight (10:00 a.m. to 16:00 p.m.) when compared with the surrounding environment. Such cooling fabrics can be made from commonly used fabrics on a large area, suggesting their potential use in fields such as outdoor cooling clothing and refrigerated shipments and thus opened up a way for the preparation and application of radiative cooling fabrics.

Colloidal inorganic nano- and microparticles for passive daytime radiative cooling

“…Furthermore, the application of RCMs to fabrics or textiles has been reported by researchers by incorporating NPs or MPs in the matrix to allow for efficient personal thermal management [ 21 ]. These RC fabrics have tremendous potential in many emerging applications such as packaging [ 61 , 75 ], transportation [ 76 , 77 ], vehicle cooling [ 16 , 22 ], and smart devices [ 48 , 50 , 59 , 60 ]. Owing to the high dispersity of colloidal NPs and MPs in various types of solvents or polymer mediums, RC particles can be easily incorporated into fabric or textiles.…”

“…Moreover, it caused a temperature drop of 6 ℃ under direct sunlight with an average radiative cooling power density of 61 W/m 2 . Fabric-format RCMs can be fabricated simply through in situ synthesis of SiO 2 NPs in polyester cloth [ 60 ]. By using the Stober method, which is well known as a synthetic method for silica, SiO 2 NPs can be formed in-situ on polyester cloth through hydrolysis and condensation of the silane monomer in the presence of ammonia solution (Fig.…”

Superhydrophobic SiO2–Glass Bubbles Composite Coating for Stable and Highly Efficient Daytime Radiative Cooling

“…Over the last few years, PDRC has been well developed by designing materials with high reflectivity and emissivity. These include inorganic photonic crystal structures, − inorganic powders, , porous metal oxides, , metal–polymer, , polymer porous films, , nanoparticle textiles, , and metamaterials . For example, Fan’s group first proposed the use of metal–dielectric photonic structures for PDRC structure design in 2013 to achieve daytime cooling radiation through specific photonic crystal structures.…”

“…The phonon-polariton Mie resonance produced by SiO 2 emits thermal radiation strongly into the universe, thus achieving a cooling of 10.6 °C in direct sunlight. In order to enhance the reflectivity of radiation-cooled materials, the introduction of inorganic particles such as Al 2 O 3 , SiO 2 , TiO 2 , and ZrO 2 into other materials to reconstruct the structure has also been investigated. ,,, If all the materials reported could be utilized on a large scale in real life, their unique properties could play a major role in mitigating the urban heat island effect.…”

“…In order to enhance the reflectivity of radiation-cooled materials, the introduction of inorganic particles such as Al 2 O 3 , SiO 2 , TiO 2 , and ZrO 2 into other materials to reconstruct the structure has also been investigated. 20,21,34,35 If all the materials reported could be utilized on a large scale in real life, their unique properties could play a major role in mitigating the urban heat island effect. However, advanced cooling materials are still very limited in practical applications due to their poor weather resistance.…”