Bioinspired Intelligent Solar‐Responsive Thermally Conductive Pyramidal Phase Change Composites with Radially Oriented Layered Structures toward Efficient Solar–Thermal–Electric Energy Conversion

Abstract

AbstractTo remedy the drawbacks of weak solar‐thermal conversion capability, low thermal conductivity, and poor structural stability of phase change materials, pyramidal graphitized chitosan/graphene aerogels (G‐CGAs) with numerous radially oriented layers are constructed, in which the long‐range radial alignment of graphene sheets is achieved by a novel directional‐freezing strategy. A G‐CGA/polyethylene glycol phase change composite exhibits a thermal conductivity of 2.90 W m−1 K−1 with a latent heat of 178.8 J g−1, and achieves a superior solar‐thermal energy conversion and storage efficiency of 90.4% and an attractive maximum temperature of 99.7 °C under a light intensity of 200 mW cm−2. Inspired by waterlilies, solar‐responsive phase change composites (SPCCs) are designed for the first time by assembling the G‐CGA/polyethylene glycol phase change composites with solar‐driven bilayer films, which bloom by day and close by night. The heat preservation effect of the solar‐driven films leads to a higher temperature of SPCC for a longer period at night. The SPCC‐based solar–thermal–electric generator achieves output voltages of 499.2 and 1034.9 mV under light intensities of 200 and 500 mW cm−2, respectively. Even after stopping the solar irradiation, the voltage output still occurs because of the latent heat release and the heat preservation of the films.