Design and fabrication of bifunctional microcapsules for solar thermal energy storage and solar photocatalysis by encapsulating paraffin phase change material into cuprous oxide

摘要

Abstract This article reported the design and fabrication of bifunctional microcapsules for solar photocatalysis and solar thermal energy storage by using cuprous oxide (Cu2O) as an inorganic shell to encapsulate a paraffin-type phase change material (PCM), n-eicosane. Such a new type of microcapsules was synthesized successfully by using an emulsion templating self-assembly method along with in-situ precipitation. The chemical structures of the resultant microcapsules were determined by Fourier-transform infrared spectroscopy, and the elemental distributions of microcapsule shell were confirmed by X–ray photoelectron spectroscopy and energy-dispersive X–ray spectroscopy. The scanning and transmission electronic microscopic observations demonstrated that the microstructures and morphologies of microcapsules were influenced significantly by the surfactant and alkali concentrations as well as the portion of cupper source for the synthesis. After the synthetic condition was optimized, the obtained microcapsules exhibited an interesting octahedral morphology and a typical core-shell structure. The thermal analysis results suggested that the microcapsules synthesized at the optimum condition not only obtained high encapsulation and energy-storage efficiencies but also presented a high thermal stability and phase-change reliability. Most of all, the microcapsules obtained a solar thermal energy-storage capability through solar photothermal conversion and also exhibited a high solar photocatalytic activity to organic dyes u