A novel bio-based composite: High-performance shape-stabilized phase change material for solar thermal collection

To address limitations of organic phase change materials (PCMs) applied in solar energy applications, such as leakage, low thermal conductivity, and inefficient photothermal conversion, this paper presented a novel biomass-based composite PCM fabricated via an environmentally friendly method. The composite material (PCB@SA) was constructed using a κ-carrageenan (KC)/potassium alginate (PA) matrix embedded with polydopamine (PDA)-functionalized hexagonal boron nitride (h-BN), followed by vacuum-assisted impregnation with stearic acid (SA). Among them, the composite material achieved a loading rate of 76 % for SA, exhibiting a high enthalpy value of 160.96 J/g and an enthalpy efficiency of 97.24 %. The resulting composite achieved a high thermal conductivity of 0.91 W/(m·K) while maintaining exceptional thermal reliability, with 97.46 % enthalpy retention over 200 cycles and 99.5 % mass retention after 30 min at 100 °C. Notably, the composite exhibited outstanding photothermal conversion performance reaching an efficiency of 86.74 %. Therefore, this composite material, with its green fabrication process and outstanding overall advantages, holds strong potential for applications in solar energy and other fields.