Nano‐Cu Particles Modified Graphene‐Polyvinyl Alcohol Foam Composite Phase Change Materials for Efficient Solar‐Thermal Conversion and Storage

Graphene composite phase change materials (PCMs) show great application potential in solar energy conversion and storage due to their strong light absorption and high thermal conductivity. To further enhance the photothermal conversion and leakage prevention performance of graphene composite PCMs. This article adopts a “point‐surface” modification strategy. Through a hydrothermal reduction self‐assembly method, nanocopper particles are doped into polyvinyl alcohol (PVA) cross‐linked graphene nanosheets to construct a novel graphene nanosheet‐nanosized Cu particle/polyethylene glycol (PEG) composite PCMs. The random distribution of nanocopper particles significantly enhances the spectrum absorption capacity and interfacial heat transfer efficiency of the graphene skeleton. The results show that the thermal conductivity of PEG/PG–Cu 0.06 reaches 0.793 W/m −1 k −1 , which is 317.4% of pure PEG. Its latent heat enthalpy value reaches 185.7 J g −1 , and the enthalpy value attenuation rate after 200 thermal cycles is less than 0.21%. Moreover, when the simulated light intensity was 120 mW cm −2 , the PEG/PG–Cu 0.06 photothermal conversion efficiency is 86.2%. Meanwhile, the cross‐linked network formed by PVA and graphene can effectively inhibit PEG leakage, and the leakage rate of PEG/PG–Cu 0.06 is 21.6%. Additionally, the 3D graphene‐PVA matrix modified by nano‐Cu particles is used to improve the thermal conductivity and the spectrum adsorption capacity of composite PCMs, which have excellent photothermal conversion performance and thermal stability and have great application prospects in solar energy heat storage.