The reinforced photothermal effect of conjugated dye/graphene oxide-based phase change materials: Fluorescence resonance energy transfer and applications in solar-thermal energy storage

The development of shape-stabilized phase change materials (ss-PCMs) with efficient solar energy conversion performance, large energy storage capacity, and high thermal conductivity is essential for solar energy utilization. Here, novel photo-driven composite ss-PCMs were successfully fabricated by grafting blue anthraquinone dyes (Bdye) on carboxylated graphene oxide (GO) and impregnating poly(ethylene glycol) (PEG) into Bdye-grafted GO nanoconjugate system (GO-co-Bdye). The connection between grafting Bdye and GO was close enough for fluorescence resonance energy transfer from Bdye to GO. The GO-co-Bdye with a three-dimensional (3D) interconnected network structure prevented the leakage of PEG above its melting point, improved the crystalline nature, thermal stability, and thermal conductivity of composite PCMs. The composite displayed an excellent photothermal conversion capacity of 86.6% and improved thermal conductivity of 98.0% compared with the pristine PEG. The thermogravimetric analysis and differential scanning calorimetry showed that the composite PCMs exhibite high thermal stability and thermal storage performance.