Biochar-infused cellulose foams with PEG-based phase change materials for enhanced thermal energy storage and photothermal performance.

This study presents cellulose-based foams reinforced with biochar and integrated with polyethylene glycol (PEG)-based phase change materials (PCMs) to enhance thermal energy storage and photothermal performance. The foams were fabricated using an energy-efficient, non-freeze-drying method, leveraging cellulose's inherent porosity and structural integrity to create a sustainable and scalable material platform. The optimized cellulose foams exhibited a well-balanced combination of high porosity (85 %), low density (66 kg·m), and minimal shrinkage (5 %), ensuring stability across multiple applications. The hydrophilic-hydrophobic interactions between cellulose, PEG, and biochar played a crucial role in achieving uniform PCM dispersion, enabling effective thermal energy storage (130 J·g) and temperature regulation. Durability tests confirmed the stability of phase-change properties over 100 thermal cycles, demonstrating long-term material resilience. The incorporation of biochar significantly improved photothermal efficiency (85 %) by enhancing light absorption and thermal conductivity while also reinforcing the cellulose matrix. A life cycle assessment (LCA) highlighted the environmental trade-offs, where biochar contributed to carbon sequestration, while PEG introduced a higher carbon footprint but offset other environmental burdens. This work underscores the multifunctional role of cellulose in developing sustainable, bio-based thermal management materials, providing an eco-friendly alternative to conventional insulation and energy storage systems.