Heterogeneous network of 2D MOFs decorated 1D CNTs imparting multiple functionalities to composite phase change materials

Advanced multifunctional composite phase change materials (PCMs) for integrating energy storage, photothermal conversion and microwave absorption can promote the development of next-generation miniaturized electronic devices. Here, we report paraffin wax (PW)-based multifunctional composite PCMs with a hierarchical network structure assembled by two‐dimensional (2D) nickel-based metal-organic frameworks (Ni-MOFs) decorated carbon nanotubes (CNTs). The PW/CNTs@Ni-MOF composite PCMs yield an excellent photothermal energy conversion efficiency of 93.2%, as well as a good phase change enthalpy of 126.5 J/g and prominent thermal stability. Preferably, the composite PCMs also present great microwave absorption with –25.32 dB minimum reflection loss (RL_min) at 9.85 GHz. The remarkable features of the composite PCMs lie in their hierarchical network architecture and the synergistic enhancement of CNTs and MOFs, giving rise to the increased surface area, accelerated photon capture and transmission, and enhanced dielectric loss caused by polarization effects and multiple reflections, thus further boosting the latent energy storage capacity, photothermal kinetics, and microwave reflection loss. This work provides a facile and scalable approach to regulating the multifunction of composite PCMs.