Design And Performances Of Multifunctional Phase Change Materials Based On Porous Support

Phase change materials（PCMs）,which possess advantages such as large energy storage capacity,good maintenance of temperature during phase change,and high security,are potential energy harvesting and saving materials.Among various PCMs,organic PCMs（OPCMs）have gained considerable interest due to their suitable phase change temperatures for daily use.However,the single thermal energy storage function of traditional OPCMs cannot fully satisfy the diversified requirements of various fields.Therefore,the development of multifunctional OPCMs is necessary.Herein,considering porous supports with large specific area are easy to be modified,several functional supports are fabricated for constructing multifunctional OPCMs by decorating functional fillers in the pores of porous supports.The details are illustrated below:（1）A novel carbonized Cu-coated melamine foam（MF）/reduced graphene oxide（r GO）framework（MF/r GO/Cu-C）is constructed as a support for fabricating stabilized multifunctional OPCMs.MF serves as the supporting material,while r GO and Cu act as functional reinforcements.As a thermal energy storage material,polyethylene glycol（PEG）is encapsulated into MF/r GO/Cu-C through a vacuum-assisted impregnation method to obtain PEG@MF/r GO/Cu-C composite with excellent comprehensive performance.PEG@MF/r GO/Cu-C exhibits high phase change enthalpies of 148.3 J g^-1（melting）and143.9 J g^-1（crystallization）,corresponding to a high energy storage capability of 92.7%.Simultaneously,MF/r GO/Cu-C endues the composite with an enhanced thermal conductivity of 0.4621 W m^-1 K^-1,which increases by 463%compared to PEG@MF.Furthermore,PEG@MF/r GO/Cu-C displays great light-to-thermal and electric-to-thermal conversion capabilities,thermal cycle stability,light-to-thermal cycle stability,and shape stability,showing promising application prospects in energy conversion and storage aspects.（2）A functional Mo S₂-decorated carbonized MF（CMF）/r GO network（CMF/r GO/Mo S₂）for developing multifunctional OPCMs is designed,in which CMF acts as a template,while r GO and Mo S₂ serve as functional fillers.PEG is introduced into the network as an OPCM using a vacuum-assisted impregnation method.The obtained PEG@CMF/r GO/Mo S₂ composite has a high PEG content of 92.1 wt.%,which contributes to its large melting and crystallization enthalpies of 169.3 and 165.9 J g^-1,respectively.Simultaneously,the hybrid of r GO and Mo S₂ with great photon harvesting and electrically conductive properties endows the composite with light-to-thermal and electric-to-thermal energy conversion functions.Moreover,the synergistic effect of the three-dimensional porous structure and high dielectric loss capability of CMF/r GO/Mo S₂ renders the composite a microwave absorbing material.As a result,the minimum reflection loss and maximum efficient bandwidth of PEG@CMF/r GO/Mo S₂ achieve-32.49 d B and 6.16 GHz at thicknesses of 2.1 and 2.4 mm,respectively.Overall,PEG@CMF/r GO/Mo S₂simultaneously exhibits excellent thermal energy storage,energy conversion,and microwave absorbing properties,possessing great prospects in energy storage and microwave absorbing applications.