An All-In-One Hollow NiC/Reduced Graphene Oxide Aerogel as a Multifunctional Platform for Composite Phase-Change Materials with Superior Synergistic Thermal Storage, Photothermal Conversion, and Remarkable Microwave Absorption

High-performance electronics and renewable energy systems increasingly demand phase-change materials (PCMs) capable of both thermal regulation and electromagnetic interference mitigation. However, conventional PCMs offer only single functionality. Here, we report all-in-one multifunctional composite PCMs (CPCMs) that overcome this limitation by integrating high-capacity thermal storage, efficient photothermal conversion, and exceptional microwave absorption. These CPCMs were fabricated via electrostatic self-assembly of a layered porous reduced graphene oxide (RGO)/NiC aerogel network, followed by vacuum impregnation of paraffin wax (PW). The optimized PW@RGO/NiC composite exhibits a remarkable melting enthalpy of 203.9 J·g –1 with outstanding cycling stability. The rationally designed RGO/NiC network serves as an efficient phonon transfer bridge, enhancing thermal conductivity to 0.3804 W·m –1 ·K –1, a 242% improvement over pure paraffin. The composite also achieves an exceptional solar-thermal conversion efficiency of 95.08%, enabling effective solar energy harvesting. Notably, its porous architecture provides superior impedance matching, yielding strong electromagnetic wave attenuation with a minimum reflection loss of −55.39 dB at 12.89 GHz. This work establishes a material platform for integrated thermal and electromagnetic management, holding significant promises for advanced electronics and sustainable energy systems.