Synergistic Encapsulation of Phase‐Change Materials With Two Modified Biomass Carbons for Superior Thermal Performance

In this work, a novel biomass‐derived composite material is developed for advanced thermal energy storage, addressing key limitations of organic phase‐change materials (PCMs), such as low thermal conductivity and leakage. Hierarchically porous carbon scaffolds were fabricated through the carbonization of towel gourd (TLG) and wax gourd (WG) biowastes at varying temperatures. These sustainable carbon matrices were subsequently utilized to efficiently encapsulate myristic acid (MA) and tetradecanol (TD), leading to the successful synthesis of four distinct bio‐based composite PCMs (CPCMs) with enhanced structural stability and performance. The results indicate that the high‐temperature pyrolysis can increase the specific surface area of biomass; the specific surface area of TLGB950 and WGB950 reached 157.078 and 166.995 m 2 /g, and the phase transition temperatures of MA/TLGB950, MA/WGB950, TD/TLGB950, and TD/WGB950 were 52.00°C, 52.02°C, 36.32°C, and 36.58°C, with the latent heat of change being 110.38, 108.37, 154.56, and 169.36 J/g, respectively. After 500 cycles, it still exhibits satisfactory shape stability, thermal stability, and heat storage capacity, demonstrating the excellent encapsulation capability of biomass porous carbon. This work not only provides a novel pathway for the valorization of biomass waste but also underscores the significant application potential of these biomass‐based CPCMs in low‐ to medium‐temperature thermal management, especially for electronics and building integration.