Anisotropic nanocellulose-based aerogels for radiative cooling

Area of Science:

• Materials Science
• Sustainable Energy
• Nanotechnology

Background:

• Global energy conservation and emission reduction are critical goals.
• Passive radiation cooling is a promising zero-consumption technology for cooling.
• Developing high-performance, sustainable cooling materials is essential.

Purpose of the Study:

• To create a high-performance passive radiation cooling material using sustainable resources.
• To investigate the properties and cooling effects of a novel aerogel composite.

Main Methods:

• Utilized freeze-casting to fabricate a hydrophobic aerogel from polyvinyl alcohol (PVA) and nanocellulose fibers (CNFs).
• Optimized the aerogel composition (borax/CNFs = 2:5) and processing via directional freezing.
• Characterized mechanical properties, density, hydrophobicity, solar reflectivity, emissivity, and thermal insulation.

Main Results:

• Achieved a low-density (38.1 mg·cm⁻³) aerogel with excellent mechanical strength (291 KPa).
• The hybrid aerogel demonstrated high solar reflectivity (96.8%) and high emissivity (97.2%) within the atmospheric window.
• Exhibited good thermal insulation (34.56 mW·m⁻¹·K⁻¹) and a significant radiative cooling effect, approximately 9 °C cooler than EPS under sunlight.

Conclusions:

• The developed cellulose-based aerogel is a high-performance material for passive radiative cooling.
• Its properties of strength, hydrophobicity, and efficient radiative cooling offer great potential for energy conservation applications.
• This research provides insights into developing advanced, sustainable materials for cooling technologies.