A biomass-derived hierarchical porous carbon-carbonized rice (CNR) with high porosity (80.9%) and large pore volume (3.45 cm3/g) was prepared using natural and accessible biomass rice as template. Then the CNR was applied to pack polyethylene glycol 2000 (PEG2000) phase change material (PCM) via vacuum impregnation method. The phase change property, thermal storage/release and solar photothermal conversion performance of the materials were explored. The results show that the maximum loading of PEG2000 is 75 wt%. Compared with pure PCM, the supercooling degree of PEG2000/CNR composite material is reduced by 57%, that is, CNR promotes the heterogeneous nucleation of PEG2000. The enthalpy value of PEG2000/CNR composite is up to 137.22 J/g with an encapsulation ratio of 81.6%, showing a better thermal performance than commonly used mesoporous silicon-based, carbon-based and metal-organic framework composite PCMs. The biomass-derived CNR can significantly increase the energy storage/release rate and solar photothermal conversion efficiency (54.7%) than that of pure PCM. This work provides a new idea for the design of phase change composite materials with high heat storage density and stability for thermal and solar energy storage.
Keywords biomass-derived, hierarchical porous carbon, polyethylene glycol, composite phase change material, thermal properties, solar photothermal conversion