Thermal energy harvesting and storage with phase change materials (PCMs) have attracted extensive exploration in solar-thermal utilization. Solving leakage issue of PCMs and improving the energy absorption, storage and transport are facing great challenges. As a typical aerogel with porous structure and strong light absorption, carbon aerogel (CA) becomes an attractive support material for PCMs. In this work, the carbon aerogels reinforced melamine foam (CA/Foam) were prepared by sol-gel polymerization, freeze drying and carbonization. To further optimize the pore structure and optical properties, CO2 activation is implemented to obtain the super black reinforced melamine foam, which is named as activated CA/Foam (ACA/Foam). After vacuum adsorption of PW, the prepared paraffin wax/activated carbon aerogel/foam (PW/ACA/Foam) maintains high thermal storage density of 143.4 J/g and shows excellent thermal stability, which can effectively solve the shortcoming of PCMs leakage due to rich pore structure. Encouragingly, the photothermal conversion efficiency of PW/ACA/Foam composite material can reach 92.1% with 5% weight fraction of resorcinol and formaldehyde in the precursor solution. The thermal conductivity of PW/ACA/Foam is 0.71 W/(m·K), 97.2% higher than pure PW, which will be the potential material for composite PCMs applied in solar energy utilization.
Carbon aerogel; Photothermal conversion; Phase change material; Photothermal energy storage