Multifunctional composite phase change materials with CNTs/SiC-modified epoxy coating for synergistically enhanced solar energy storage and photothermal conversion

• Introduced modified epoxy resin and carbon foam multistage encapsulation of phase change materials. • The composite maintained a high latent heat of 143.1J⋅g −1 with excellent thermal stability after 200 thermal cycles. • Photothermal conversion coating demonstrated significant potential for long-term solar thermal energy storage applications. • The composite exhibited enhanced mechanical strength and compressive performance due to the synergistic structure. Developing multifunctional composite phase change materials (PCMs) featuring enhanced photothermal energy conversion and storage performance is of vital importance, yet traditional organic PCMs suffer from inherent drawbacks, including leakage and poor thermal conductivity throughout the phase change process. To solve this problem, a new PCM design is provided, where stearic acid (SA) was employed as a latent heat storage unit, and carbon foam (CF) was served as a supporting framework. In this design, CNTs/SiC composite nanoparticles were uniformly dispersed into epoxy resin (ER) to fabricate a photothermal conversion coating. The modified epoxy resin (MER) coating acted as a protective effect for the internal PCMs, effectively mitigating leakage during phase transitions. With the incorporation of 9 wt% CNTs/SiC, the prepared composite PCMs retained the high latent heat (143.5J⋅g −1 ) and excellent photothermal conversion efficiency (96.76 %). Furthermore, the latent heat of the material showed a minimal reduction of only 0.4 % following 200 thermal cycles. These results demonstrate the potential of composite PCMs for efficient solar energy harvesting and storage in thermal regulation systems.