Cellulose based hierarchical structural colored wood composite material for daytime radiative cooling

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Daytime radiative cooling (DRC) offers a sustainable alternative to energy-intensive cooling methods, aiding carbon neutrality.
• Current DRC materials often have limited aesthetic applications due to their white or mirror-like appearances.

Purpose of the Study:

• To develop a novel, aesthetically versatile photonic radiative cooling material using delignified wood.
• To explore the potential of cellulose nanocrystal (CNC) and xylan self-assembly for creating tunable structural colors on wood substrates.

Main Methods:

• Utilizing delignified wood as a cellulosic base for the radiative cooling material.
• Employing bottom-up self-assembly of CNC and xylan to create a structural colored photonic layer with tunable visible spectrum appearance.
• Incorporating PDMS to enhance hydrophobicity without compromising cooling performance.

Main Results:

• The developed material exhibits high solar reflectance (95.0%) and high atmospheric window emittance (93.0%), leading to efficient radiative cooling.
• Structural colored CNC films and wood materials achieved outdoor cooling effects of 2.1°C and 4.3°C, respectively.
• Patterned CNC coatings on wood demonstrated dual functionality as decorative and cooling materials.

Conclusions:

• Hierarchically structured, color-tunable wood-based materials offer a promising solution for efficient daytime radiative cooling.
• These materials provide a viable option for energy-saving, decorative building materials, contributing to sustainable architecture.