Photo-to-thermal conversion and energy storage of polyethylene glycol/copper sulfide composite PCMs

A novel composite PCM was facilely synthesized, which exhibited enhanced absorption peaks at visible and near-infrared region, and the photothermal conversion and storage efficiency was outstanding under simulated and actual sunlight irradiation. The latent heat storage of PCMs has gained increasing attention in the solar energy application field due to their high thermal energy storage density. However, the lack of energy conversion ability of the organic PCMs results in the low utilization efficiency of solar energy. Herein, we report a novel PEG/Ti 3 C 2 T x layered composite PCM with superior photothermal storage capability, which consists of stacked Ti 3 C 2 T x nanosheets and PEG filled within the spaces between the flakes. The resulting composites exhibited a strong absorption capacity for electromagnetic waves at the UV-Vis-NIR region. Notably, there are two enhanced absorption bands at the visible and near-infrared regions due to the localized surface plasmon resonance (LSPR) effect of the Ti 3 C 2 T x nanosheets, which endows the composite PCM with excellent photo-to-thermal storage efficiencies (up to 94.5%) under actual solar light irradiation. In addition, the composite PCM also possesses a high energy storage density and form-stable property before and after the phase transition. These results indicate that the synthesized composite presents superior comprehensive properties suitable for solar energy storage applications.