Heat dissipation is a severe barrier for ever‐smaller and more functionalized electronics, necessitating the continuous development of accessible, cost‐effective, and highly efficient cooling solutions. Metals, such as silver and copper, with high thermal conductivity, can efficiently remove heat. However, ultralow infrared thermal emittance (<0.03) severely restricts their radiative heat dissipation capability. Here, a solution‐processed chemical oxidation reaction is demonstrated for transfiguring “infrared‐white” metals (high infrared thermal reflectance) to “infrared‐black” metametals (high infrared thermal emittance). Enabled by strong molecular vibrations of metal‐oxygen chemical bonds, this strategy via assembling nanostructured metal oxide thin films on metal surface yields infrared spectrum manipulation, high and omnidirectional thermal emittance (0.94 from 0 to 60°) with excellent thermomechanical stability. The thin film of metal oxides with relatively high thermal conductivity does not hinder heat dissipation. “Infrared‐black” meta‐aluminum shows a temperature drop of 21.3 °C corresponding to a cooling efficiency of 17.2% enhancement than the pristine aluminum alloy under a heating power of 2418 W m−2. This surface photon‐engineered strategy is compatible with other metals, such as copper and steel, and it broadens its implementation for accelerating heat dissipation.
Radiative cooling is an emerging cooling technology that can passively release heat to the environment. To obtain a subambient cooling effect during the daytime, chemically engineered structural materials are widely explored to simultaneously reject sunlight and preserve strong thermal emission. However, many previously reported fabrication processes involve hazardous chemicals, which can hinder a material's ability to be mass produced. In order to eliminate the hazardous chemicals used in the fabrication of previous works, this article reports a white polydimethylsiloxane (PDMS) sponge fabricated by a sustainable process using microsugar templates. By substituting the chemicals for sugar, the manufacturing procedure produces zero toxic waste and can also be endlessly recycled via methods widely used in the sugar industry. The obtained porous PDMS exhibits strong visible scattering and thermal emission, resulting in an efficient temperature reduction of 4.6 °C and cooling power of 43 W m−2under direct solar irradiation. In addition, due to the air‐filled voids within the PDMS sponge, its thermal conductivity remains low at 0.06 W (m K)−1. This unique combination of radiative cooling and thermal insulation properties can efficiently suppress the heat exchange with the solar‐heated rooftop or the environment, representing a promising future for new energy‐efficient building envelope material.
more » « less- NSF-PAR ID:
- 10378348
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Science
- Volume:
- 8
- Issue:
- 23
- ISSN:
- 2198-3844
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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