Cyclized polyacrylonitrile@carbon nanotubes reinforced graphene aerogel phase change composites for efficient solar-thermal-electric energy conversion

Phase change materials (PCM) have great potential in storing and releasing thermal energy, but the poor light absorption, low thermal conductivity, and weak shape stability severely restrict the absorption, conversion, and utilization of solar energy. In this study, inspired by the articular structure, we prepared cyclized polyacrylonitrile@carbon nanotubes (CPAN@CNT)/graphene hybrid aerogel (CPAN@CNT/GA). The introduction of CPAN@CNT enhanced the mechanical properties and thermal conductivity of the aerogels, establishing continuous and stable heat transfer pathways and ensuring stable encapsulation of PCMs in the following step. Under a compressive strain of 50%, the compressive strength of CPAN@CNT/GA increased to 7.8 kPa, demonstrating stable compression resilience. Paraffin wax (PW) as the PCM was integrated into CPAN@CNT/GA by vacuum impregnation to fabricate PW/CPAN@CNT/GA shape-stabilized phase change materials (SSPCMs). PW/CPAN@CNT/GA exhibited a high latent heat (190.1 J g -1 ), a high thermal conductivity (0.764 W m -1 K -1 ), and exceptional photothermal conversion efficiency (93.7%). PW/CPAN@CNT/GA also showed its advanced solar-thermal-electric energy conversion potential. The output voltage was sufficient to power the electronic devices with a rated voltage of 2V under simulated sunlight (2 kW m -2 ), and provided additional operating time even in the absence of light. This study presents a feasible and effective method for fabricating SSPCMs with high latent heat retention, possessing efficient solar-thermal-electric energy conversion.