Design and synthesis of SiO2/TiO2/PDA functionalized phase change microcapsules for efficient solar-driven energy storage

To improve the solar-thermal conversion efficiency of encapsulated phase change materials (PCM), a novel hierarchical SiO2/TiO2/polydopamine (ES-T-PDA) composite shell was designed and synthesized through interlayer arrangement on an encapsulated PCM. The corresponding structures, chemical compositions, crystallinity, and thermal induction capacity of the ES-T-PDA nano/microcapsule shell was extensively investigated. The articulated system attained phase-change enthalpies around 125.92 J/g, with a thermal heating increase of ~2.16 ± 0.34 °C due to stimulated light-driven localized heating for efficient solar energy storage. This study confirmed that the combination of SiO2, TiO2 and PDA layered shell was a practical way not only to enhance the structural stability, durability and solar photocatalytic activity but also to promote localized surface photothermal effect due to light scattering effect and visible light absorption. By coupling these two features, the structural design developed in this work displays a considerable prospect for straightforward solar energy employment in various PCM solar-thermal conversion applications such as temperature management of greenhouses, solar water heating systems, solar cookers, and solar-thermal electricity generating systems.