Polyethylene glycol (PEG)/silicon dioxide grafted aminopropyl group and carboxylic multi-walled carbon nanotubes (SAM) composite as phase change material for light-to-heat energy conversion and storage

The development of light-to-heat energy conversion and storage materials with high thermal conductivity and stability is very helpful to overcome limitations of using solar energy. Herein, novel light-induced phase change materials (PCMs) were synthesized by sol-gel method using polyethylene glycol (PEG) as phase change material, silicon dioxide (SiO2) network with aminopropyl group and carboxylic multi-walled carbon nanotubes (MWCNTs-COOH) as supporting material (SAM). The developed PEG/SAM have many advantages, including improved thermal conductivities (43.5–108.7% increase as compared to PEG), high energy storage densities (116–133 J/g), high light-to-heat energy conversion and storage efficiency (85.8–88.3%), and good form-stable performance. Moreover, the PEG/SAM maintained excellent chemical stability and thermal performance durability after 500-cycle thermal experiments and 200 cycles light-induced phase transitions. Thus, the developed light-to-heat energy conversion and storage PCMs have the potential for many applications and the efficient utilisation of solar energy.