Polypyrrole-boosted photothermal energy storage in MOF-based phase change materials

Infiltrating phase change materials(PCMs)into nanoporous metal–organicframeworks(MOFs)is accepted as a cutting-edge thermal energy storageconcept.However,weak photon capture capability of pristine MOF-basedcomposite PCMs is a stumbling block in solar energy utilization.Towards thisgoal,we prepared advanced high-performance pristine MOF-based photothermalcomposite PCMs by simultaneously integrating photon absorber guest(polypyrrole[PPy])and thermal storage guest(1-octadecanol[ODA])intoan MOF host(Cr-MIL-101-NH2).The coated PPy layer on the surface ofODA@MOF not only serves as a photon harvester,but also serves as a phononenhancer.Resultantly,ODA@MOF/PPy composite PCMs exhibit intense andbroadband light absorption characteristic in the ultraviolet–visible–nearinfraredregion,and higher heat transfer ability than ODA@MOF.Importantly,the photothermal conversion and storage efficiency of ODA@MOF/PPy-6%is up to 88.3%.Additionally,our developed MOF-based photothermalcomposite PCMs also exhibit long-standing antileakage stability,energystorage stability,and photothermal conversion stability.The proposed coatingstrategy and in-depth understanding mechanism are expected to facilitate thedevelopment of high-efficiency MOF-based photothermal composite PCMs insolar energy utilization.