Erythritol supported by carbon nanotubes reinforced alumina-silica aerogels as novel form-stable phase change materials with high photothermal conversion efficiency and greatly suppressed supercooling

Form-stable phase change materials (FSPCMs) with excellent photothermal conversion efficiency could achieve simultaneously conversion of solar energy to thermal energy and storage of the obtained thermal energy, and thus are beneficial for alleviating energy crises and environmental pollution. In the presented work, acid treated multiwalled carbon nanotubes (ACNTs) reinforced alumina-silica aerogels were synthesized via ambient pressure drying followed by heat treatment. Then the combination of photothermal conversion and phase change latent heat storage was realized by confining erythritol (ET) in the composite aerogels via vacuum infiltration. The obtained FSPCMs had a high ET loading of 90 wt% with high melting enthalpies of ∼280 J/g, and exhibited high photothermal conversion efficiency due to the doping of ACNTs. Specifically, when the aerogel skeleton contained 5 wt% ACNTs of its own mass, the corresponding FSPCM showed an excellent photothermal conversion efficiency of 74.03 %. Moreover, the prepared FSPCMs in grams level solidified at around 104 °C, indicated that the severe supercooling of the FSPCMs was greatly suppressed. Besides, the FSPCMs also possessed better thermal conductivity than pure ET. When the aerogel skeleton was reinforced by 4 wt% ACNTs of its own mass, the obtained FSPCM exhibited an improved thermal conductivity of 55.6 % higher than pure ET. Meanwhile, the FSPCMs showed good thermal reliability over 80 melting/crystallizing cycles. Consequently, the FSPCMs reported here have potential applications in solar thermal applications and latent heat storage systems.