Enhanced solar thermal energy storage of phase change composites supported by copper foam modified with metal–organic-frameworks-derived multi-walled carbon nanotube networks

The limited thermal conductivity, inadequate photothermal conversion efficiency, and poor shape stability of organic phase change materials (PCMs) such as paraffin wax hinder their practical application in solar thermal energy storage and thermal management systems. To address these challenges, this study introduces a novel phase change composite by integrating copper foam modified with metal–organic framework-derived multi-walled carbon nanotube networks. The copper foam surface was functionalized through spontaneous crystallization of MOFs followed by carbonization, forming a hierarchical porous structure that enhances thermal conductivity, solar absorption, and PCM encapsulation. Experimental results demonstrate that the optimized phase change composite achieves a thermal conductivity of 7.3 W/(m·K)—36.5 times higher than pure paraffin wax and 2.9 times greater than unmodified composites. The multi-walled carbon nanotube networks −modified copper foam synergistically improves photothermal conversion, achieving a maximum temperature of 88.5 °C under 1 sun irradiation, 37.4 °C higher than pure paraffin wax. Additionally, the composite exhibits exceptional shape stability with 99.2 % mass retention after leakage testing, attributed to the enhanced capillary forces and porous structure. This work advances PCM technology by uniquely combining metal–organic framework −derived carbon networks with copper foam, offering a scalable and cost-effective strategy to overcome existing limitations in thermal storage materials. The developed phase change composite demonstrates significant potential for applications in solar energy harvesting, electronic thermal management, and industrial waste heat recovery.