Polyimide/phosphorene hybrid aerogel-based composite phase change materials for high-efficient solar energy capture and photothermal conversion

Solar energy is the cleanest and most abundant renewable energy source that can be utilized to displace fossil fuels and provide an effective solution for future energy shortage and climate change. Aiming at enhancing the capture efficiency of solar photothermal energy, we developed a novel type of phase-change composites based on polyimide (PI)/phosphorene (PR) hybrid aerogel and polyethylene glycol (PEG). The composites were prepared by fabricating a series of PI/PR hybrid aerogels with different loadings of PR nanosheets using freeze-drying and thermal imidization techniques, followed by vacuum impregnation of PEG as a phase change material into the aerogel framework. The obtained hybrid aerogels exhibited a lightweight nature with a density of 21.9 mg·cm−3 when 16 wt% PR nanosheets were incorporated, resulting in an extremely high PEG loading of 4067% in the aerogel system. The combination of PI and PR nanosheets leads to a significant enhancement in solar light absorption and photothermal energy conversion for the hybrid aerogel/PEG composites. The loading amount of PEG was also improved remarkably due to an increase in the volume capacity of the hybrid aerogels resulting from the introduction of PR nanosheets. The resultant hybrid aerogel/PEG composites not only exhibit a high latent-heat capacity of over 170 J·g−1 and a high photothermal conversion efficiency of 82.5%, but also show good thermal impact resistance to keep their original shape and form well after heating at 80 °C for 20 min and maintain a high thermal cycle stability after thermally cycled for 500 times. These superior performances make the hybrid aerogel/PEG composites capable of dealing with a wide range of applications in solar photothermal energy capture and storage. This study provides a promising strategy for the design and development of high-performance and lightweight composite PCMs to meet the requirement of applications for efficient utilization of solar energy.