Strong double networked hybrid cellulosic foam for passive cooling

Area of Science:

• Materials Science
• Sustainable Energy
• Nanotechnology

Background:

• Passive radiative cooling is a key zero-energy technology for environmental protection and energy conservation.
• Traditional radiative cooling materials face challenges in balancing mechanical strength and cooling performance, hindering scalable production.

Purpose of the Study:

• To develop a robust and efficient passive radiative cooling material using biomass.
• To enhance mechanical properties and solar scattering for improved cooling performance.

Main Methods:

• Fabrication of a double-networked hybrid cellulosic foam by crosslinking cellulose nanofibers (CNF) and polyvinyl alcohol (PVA) using a silane coupling agent.
• Incorporation of nano zinc oxide (ZnO) and metal-organic frameworks (MOF) to enhance mechanical strength and solar scattering.
• Utilizing a freeze-drying process for material synthesis.

Main Results:

• The hybrid cellulosic foam achieved high solar reflectivity (0.965) and infrared emissivity (0.94).
• The material exhibited ultrahigh mechanical strength and low thermal conductivity.
• Demonstrated a daytime cooling efficiency of 7.5 °C under direct sunlight in a hot climate.

Conclusions:

• The developed hybrid cellulosic foam is a high-performance material for outdoor thermal regulation.
• Biomass-derived materials show significant potential for thermal management applications.
• This work offers possibilities for energy conservation, environmental protection, and green building materials.