One-step synthesis of graphene-based composite phase change materials with high solar-thermal conversion efficiency

Graphene-based composite phase change materials (PCMs) exhibit great potential applications in the field of solar-thermal energy conversion and storage, recently, due to their attracting capability of endowing the PCMs with superior light absorption ability and preventing the liquid phase leakage during the transition process. However, current synthesis methods of graphene-based composite PCMs usually involve complicated multi‐step procedures, greatly hindering its large-scale preparation for the practical application of the solar-thermal energy utilization technique. Herein, we report a facile and straightforward one-step strategy of constructing graphene-based shape-stable composite PCMs with polyethylene glycol (PEG) in situ filled into a graphene oxide (GO) network structure hydrogel. Using this one-step strategy, we achieve a high PEG loading capacity up to 95 wt% in the graphene-based composite PCMs. The composite PCMs also have a relatively constant phase change enthalpy of 162.8 J/g even after 1000 heating–cooling cycles. Most importantly, the composites exhibit a superior solar-thermal conversion ability with the conversion efficiency as high as 93.7%. Compared with the currently reported synthetic routes, the complicated processing steps are greatly reduced in this one-step synthesis strategy. This work proposes a simple and efficient method of synthesizing graphene-based composite PCMs with superior solar-thermal conversion efficiency, which may have great potential applications in the field of solar-thermal energy conversion and storage.