Enhanced Light‐Thermal Absorption and Conversion Capacity of Diatomite‐Based Polyethylene Glycol Composites Phase Change Materials by Introducing Polydopamine

ABSTRACT The application of phase change energy storage techniques effectively addresses energy shortages. By combining photothermal conversion materials with phase change materials, this approach yields composite phase change energy storage materials with superior photothermal conversion performance and high phase change enthalpy. Porous raw diatomite (RD) was used as a substrate to initiate the self‐polymerization of dopamine hydrochloride, forming a polydopamine (PDA) layer on the RD surface. Subsequently, the substrate was impregnated with polyethylene glycol (PEG) under vacuum to synthesize the RD/PDA/PEG composite phase change energy storage material. This study demonstrated that PDA‐functionalized RD enhances PEG encapsulation and improves the light absorption efficiency of the RD/PDA/PEG composite. Furthermore, the incorporation of PDA significantly boosts the photothermal absorption and conversion efficiency of the composite material. Notably, the photothermal conversion efficiency of RD/PDA/PEG‐12 reached 78.8%.