Fabrication of Radiative Cooling Function on Wood Surface via TCMs@ZnO

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Radiative cooling materials offer passive heat management but often suffer from high cost, complex processing, and poor outdoor durability. Here, a scalable strategy was developed to fabricate thermochromic radiative cooling wood by integrating thermochromic microcapsules (TCMs) and ZnO nanoparticles into a phenolic resin coating on rubberwood ( Hevea brasiliensis ) and fir ( Cunninghamia lanceolata (Lamb.) Hook.). The in situ synthesized ZnO-modified resin formed uniform micro/nano-structured coatings with strong adhesion and reversible thermochromic behavior, increasing the ultraviolet (UV)-visible reflectance by approximately 44.7% when the wood temperature ( T ) exceeded the critical transition temperature ( T c = 28 °C). The hybrid coating enhanced hydrophobicity, self-cleaning, and UV resistance, ensuring long term optical stability. Outdoor tests demonstrated effective thermal regulation performance, with maximum surface and subsurface temperature reductions of 10.4 and 7.2 °C, respectively, while wooden house models achieved surface and indoor temperature decreases of 3.3 and 2.5 °C, respectively. EnergyPlus simulations further indicated annual cooling energy saving rates up to 19.5% in hot climates. This study presents a multifunctional thermochromic radiative cooling wood with integrated dynamic optical regulation, offering a sustainable and scalable route toward energy-efficient and climate-adaptive building materials.