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Abstract

Amid growing climate challenges and the need to decarbonize energy systems, the development of renewable materials has become a cornerstone of bio-innovation. Wood, with its intrinsic hierarchical porosity and mechanical robustness, emerges as a promising candidate for engineering multifunctional materials to meet energy and environmental demands. However, novel applications of wood require enhanced control over light absorption, hygroscopicity, and rigidity, necessitating advanced structural and chemical modifications. This thesis explores the potential of wood, specifically balsa and basswood, as a foundational material for sustainable energy management. The research targets solar energy conversion, thermal regulation, and rainfall energy harvesting through synergistic physical and chemical transformations. By integrating materials science, nanotechnology, and sustainable design principles, the work advances wood-based systems that bridge the gap between renewable feedstocks and high-performance energy technologies. Four interconnected studies illustrate this approach. First, a lightweight, anisotropic foam was engineered from balsa via controlled delignification, microfibrillation, and surface amorphization, resulting in tunable compressibility and enhanced thermal insulation. Second, to harness rainfall as an energy source, an all-wood triboelectric nanogenerator was fabricated through in situ lignin clustering and redistribution, improving both hydrophobicity and electrical output. Third, wood infused with a phase change material (PCM) was developed for solar-thermal energy conversion and storage, demonstrating efficient unidirectional heat transfer and stable cyclic performance for passive building temperature regulation. Lastly, lignin's inherent photothermal properties were valorized to design sustainable, high-efficiency solar absorbers integrated into wood–PCM composites. Overall, this thesis demonstrates how harmonizing wood's architecture with targeted modifications, such as lignin redistribution, anisotropic structuring, and surface functionalization, enables the development of cost-effective, scalable bioproducts for sustainable energy systems.