Comparison of UiO-66(Zr) and its derivate in shape stabilized phase change materials: Thermal storage performance and characterizations

In this study, UiO-66(Zr) and its derivative (UiO-66-C) are employed as supports to prepare shape stabilized PCM (U/SA-X and UC /SA-X) for resolving the melting leakage and poor thermal conductivity of stearic acid (SA). Thermal storage performance, including phase change enthalpy, supercooling degree, phase change temperature, thermal conductivity, and shape stability of U/SA-X and UC/SA-X, are compared. Preliminary characterization reveals that the physicochemical property evolution of the support impacts the thermal storage performance of SA. UiO-66 with microporous structure is unfavorable to enhance the shape stability of SA. U/SA-X exhibits low thermal storage efficiency and high supercooling degree owing to nanoconfinement and hydrogen bonding. By contrast, UiO-66-C possesses mesopores and graphitic structure that allows for a remarkable thermal storage performance of UC/SA-X. In detail, UC/SA-50 exhibits an ideal thermal storage performance, where the thermal conductivity (0.531 W/(m center dot K)) center dot K)) increases by 141 % in comparison to SA with a high phase change enthalpy of 93.6 J/g and low supercooling degree of 0.24 degrees C. It also shows satisfying thermal reliability that the thermal property of UC/SA-50 maintains stability even after 100 thermal cycles. In addition, the photothermal conversion efficiency of UC/SA-50 is up to 83.06 %.