Fabrication of novel slurry containing graphene oxide-modified microencapsulated phase change material for direct absorption solar collector

In this study, a new microencapsulated phase change material, paraffin@titania (TiO2)/graphene oxide (GO), was prepared by in-situ hydrolysis and polycondensation of tetrabutyl titanate and the modification of GO on the TiO2 shell. The paraffin@TiO2/GO composite consisted of spherical particles with the diameters of 2-5 µm. Raman spectra analysis confirmed the compound of GO with the TiO2 shell. The melting temperature and latent heat of the paraffin@TiO2/GO composite were 60.04 °C and 74.99 J g−1, respectively, in which the encapsulation efficiency of paraffin was calculated to be 37.93%. It was noteworthy that the paraffin@TiO2/GO composite displayed better thermal stability than paraffin due to the shell material. Most of all, the novel heat transfer slurry prepared by dispersing the paraffin@TiO2/GO composite into water exhibited higher thermal conductivity, specific heat and light absorption properties along with outstanding photo-thermal conversion performance. The prepared paraffin@TiO2/GO composite with high heat storage capability and excellent photo-thermal conversion performance enable it to be a promising candidate in direct absorption solar collector for solar energy storage.