Enhancing the thermal conductivity of n-eicosane/silica phase change materials by reduced graphene oxide

Reduced graphene oxide (rGO) sheets prepared by different methods are incorporated to boost the thermal conductivity of organic phase change materials (n-eicosane) in silica microcapsules. Low concentration (1 wt%) of graphene dosing already results in notable increase of the thermal conductivity. The preparation methods of rGO significantly affect the thermal properties of the composite. With 1 wt% dosing, sodium borohydride (NaBH₄) reduced rGO increases the thermal conductivity by 83% and decrease the phase change enthalpy by 6%. On the other hand, the thermal reduced rGO increases the thermal conductivity by 193% but leads to a 15% loss of the phase enthalpy. The difference is attributed to the different surface morphology and functional groups of the rGO sheets.