Hierarchical SiO₂@Cellulose Nanofiber Aerogels With Synergistic Optical-Thermal Regulation for High-Performance...

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Passive radiative cooling is a sustainable thermal management strategy that minimizes solar absorption and maximizes mid-infrared (MIR) emission.
• Parasitic heat gain significantly reduces the net cooling efficiency of current passive radiative cooling systems.

Purpose of the Study:

• To develop a novel aerogel material that overcomes the limitations of parasitic heat gain in passive radiative cooling.
• To create a material with integrated broadband solar reflectivity, high MIR emissivity, and low thermal conductivity for enhanced cooling performance.

Main Methods:

• Fabrication of hierarchical SiO2@cellulose nanofiber aerogels using a reversible xanthation-mediated strategy.
• In situ anchoring of SiO2 nanospheres onto cellulose nanofibers via xanthation chemistry.
• Utilizing directional ice-templating to construct lamellar hierarchical porous networks for suppressed nonradiative heat transfer.

Main Results:

• The optimized aerogel achieved 95.6% average solar reflectance and 95.3% MIR emissivity within the 8-13 µm atmospheric window.
• Ultralow thermal conductivity of 0.028 W m⁻¹ K⁻¹ was recorded.
• Achieved a time-averaged subambient cooling of 3.7°C and a net temperature reduction of 24.9°C under 1000 W m⁻² solar irradiance.

Conclusions:

• The developed aerogel material demonstrates a promising sustainable solution for energy-efficient buildings, cold-chain logistics, and advanced thermal management.
• The scalable material design framework integrates optical selectivity and thermal insulation, paving the way for next-generation cooling technologies.