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Bioinspired Switchable Passive Daytime Radiative Cooling Coatings
Tiancheng Wang1, Yuzhe Xiao2,3, Jonathan L King2
1Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
ACS Applied Materials & Interfaces
|October 9, 2023
Summary
Researchers developed a novel bioinspired coating for passive daytime radiative cooling (PDRC). This thin, robust material mimics nature to reflect sunlight and emit heat, offering an eco-friendly alternative to air conditioning.
Area of Science:
- Materials Science
- Nanotechnology
- Sustainable Energy
Background:
- Passive daytime radiative cooling (PDRC) offers an eco-friendly alternative to traditional electrical air conditioning (AC).
- Optimizing PDRC coatings requires balancing multiple performance aspects for practical application.
- Nature provides bio-inspired models for advanced material functionalities.
Purpose of the Study:
- To develop a high-performance PDRC coating inspired by natural structures.
- To achieve excellent solar reflectance, LWIR emissivity, and mechanical robustness in a thin coating.
- To demonstrate the potential of bioinspired designs for scalable and tunable cooling solutions.
Main Methods:
- Fabrication of a PDRC coating using bicontinuous interfacially jammed emulsion gels (bijels) as a template.
- Characterization of the coating's optical properties (solar reflectance and LWIR emissivity).
- Evaluation of the coating's thermal performance under direct sunlight and assessment of its mechanical properties.
Main Results:
- The bioinspired bijel PDRC coating achieved high solar reflectance (≳0.97) and LWIR emissivity (≳0.93).
- A thin coating (130 μm) demonstrated a significant subambient temperature drop of ~5.6 °C under direct sunlight.
- The PDRC coating exhibited switchable cooling capabilities and mechanical robustness, inspired by beetle exoskeletons and spongy bone.
Conclusions:
- Bioinspired PDRC coatings based on bijels offer a promising, high-performance solution for sustainable cooling.
- The developed material demonstrates excellent optical and thermal properties, along with desirable mechanical characteristics.
- This approach highlights the potential of biomimicry for creating advanced, scalable radiative cooling technologies.
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