Polypyrrole decorated radish-derived porous skeleton supported composite phase change material for efficient Joule heating and photothermal conversion

The development of multifunctional composite phase change materials (PCMs) with integrated 3D porous frameworks has emerged as a critical research frontier, aiming to concurrently address leakage suppression and versatile energy conversion capabilities for smart thermal management. In this study, a biomass-derived porous scaffold was constructed through eco-friendly freeze-drying of radish (Ra) slices, followed by in-situ polymerization of pyrrole (Py) monomers to form polypyrrole(PPy)-coated 3D honeycomb architecture. The prepared Ra@PPy/PEG composite achieved a polyethylene glycol (PEG) loading content of 91.22%. Compared to Ra/PEG, Ra@PPy/PEG shows significant improvements in PEG adsorption, shape stability, latent enthalpy, photothermal conversion, and electrothermal conversion. The latent heat capacity significantly increased from 84.92 J/g (Ra/PEG) to 146.57 J/g (Ra@PPy/PEG). The results reveal that the polymerization time (1−10 h) critically modulates the PPy coating structure and interfacial bonding strength, ultimately governing the composite's thermal/electrical performance. This bio-based composite material achieves 95.34% photothermal efficiency through broadband absorption of PPy, and 88.03% electrothermal efficiency through three-dimensional conductive network (0.79 S/cm). The developed composites show stable multi-scenario energy conversion capabilities, providing practical solutions for active and passive thermal management systems.