MXene/rGO grafted sponge with an integrated hydrophobic structure towards light-driven phase change composites

While phase change materials (PCMs) have great potential for use in solar energy storage, they suffer from a lack of shape stability and energy conversion ability. In this study, proper amination of melamine sponge (MS) was designed to construct an integrated MXene and reduced graphene oxide (rGO) structure. The MXene/rGO layer is sufficiently robust to endure the capillary pressure caused by solvent evaporation during the airdrying process. In addition, the reduction of GO using oleylamine (OA) contributes to the protection of MXene from oxidation by preventing the surface of MXene nanosheets from being exposed to oxygen and moisture. The as-designed MXene/rGO sponges have been shown to effectively enhance the thermophysical and photo absorption properties of paraffin wax (PW) in the composite PCM. The composite with the highest amount of MXene/rGO maintained 93.3% of the latent heat of pure PW. The photothermal storage efficiency can reach as high as 93.0% at an MXene content of around 1%. A thermal conductivity enhancement of 66.9% can be achieved compared to the pure MS/PW composite. Therefore, this study presents a new approach for designing of high-performance phase change composites for waste-heat recovery and solar thermal energy storage applications.