Polyvinylpyrrolidone-bridged MXene skeleton constructed by photothermal assisted sacrificial template method for phase change materials with form stability and photothermal conversion

To realize the efficient storage and conversion of solar energy, it is still a great challenge to fabricate multifunctional phase change materials (PCMs) via green and environment-friendly technologies. In this work, robust MXene@polyvinylpyrrolidone (PVP) skeleton (MP) was constructed via photothermal assisted sacrificial template method. Then, vacuum impregnation of polyethylene glycol (PEG) was performed to obtain MXene@PVP/PEG composite PCMs (MPP). The results indicate that owing to the hydrogen bond bridging effect of PVP, the MP skeleton with high interconnection and uniform pore size overcomes the problem of fragile frameworks. The composite M1P1P with the same mass fraction of MXene and PVP possesses the optimum comprehensive properties, which has high latent heat of 140.5 J/g, favorable shape stability and photothermal conversion efficiency of 96.2%. Owing to the heterogeneous nucleation sites provided by the MXene nanosheets bridged by PVP through hydrogen bonds, the nucleation activation energy of PEG is reduced. In addition, the relative enthalpy efficiency of the composite M1P1P only slightly decreased by 0.9% and 1.6% even after 100 heating–cooling cycles and 20 photothermal cycles. This research provides a new strategy for preparing multifunctional PCMs with facile and energy-saving process, showing the promising prospects in solar energy conversion and storage and comprehensive utilization of waste heat.