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.