Green Hybrid Nanocomposite Gel of Cellulose Nanofibers and Carbon Nanotubes Impregnated With <scp>DES</scp> for Renewable Low‐Grade Heat Energy Harvesting

ABSTRACT In this study, we aim to design a sustainable hybrid gel thermoelectric system with enhanced ionic thermoelectric performance and mechanical robustness. The hybrid gel was prepared by integrating cellulose nanofibers (CNF) and carbon nanotubes (CNT) into a polyvinyl alcohol (PVA) matrix, where tannic acid served as an interfacial strengthener and borax as a crosslinking agent. The incorporation of a deep eutectic solvent (DES) significantly enhances ionic mobility, yielding a Seebeck coefficient of 4.00 mV K −1 , a power factor of 115.09 μW m −1 K −2 , and an ionic conductivity of 10.35 mS cm −1 . Analytical results indicate that ionic diffusion is the dominant transport mechanism governing the improved thermoelectric response. Additionally, the CTC‐X gels retain stable mechanical integrity and display self‐healing behavior, contributing to multifunctional performance. Overall, this hybrid system demonstrates strong potential as an environmentally friendly thermoelectric material for efficient low‐grade heat harvesting.