Wood products with advanced solar-to-thermal conversion and phase change energy storage

Abstract Naturally porous wood, which has the potential to incorporate photothermal absorbers and phase-change materials, has proven to be a valuable scaffold for advanced solar-to-thermal materials and heat management technologies. Nonetheless, the light-absorbing role of lignins, which contain numerous polyaromatic rings, has been largely overlooked. Our study presents a straightforward approach to enhance solar light absorption by wood through in-situ complexation of Fe 3+ with the phenolic hydroxyl groups found in demethylated wood lignin. Phase change energy storage is subsequently achieved by in situ polymerization of polyethylene glycol and hexamethylene diisocyanate to form polyurethane in the cell lumen. This effective combination of solar-to-thermal energy conversion and phase change energy storage exploits the polyaromatic rings of lignin to enhance light-harvesting and utilizes the porous structure of natural wood for the accommodation of phase change materials. The resultant wood shows a real-life application for long-lasting solar-to-thermal conversion, thermal insulation and solar-thermal-electric conversion. This smart wood product provides a cost-effective, highly stable, and easy-to-implement solution for energy conversion and thermal management technologies.