Enhancement of Structural Stability of Graphene Aerogel for Thermal Energy Harvesting

In this work, a modified graphene aerogel with high mechanical properties is synthesized. Structural stability is a general problem of graphene aerogels. Graphene oxide (GO) is employed to provide functional groups on the surface by the oxidation of potassium permanganate (KMnO4). The internal structure of the graphene aerogel is successfully cross-linked using a cysteamine vapor method. The cross-linked graphene/cysteamine aerogel (GCA) is strong enough to reduce volume shrinkage during the phase change material (PCM) infiltration process. Furthermore, the GCA can hold some additional pure PCM into the internal space without any structural damage. To consider the application in external environments, we adopt solar light, and the GCA-supported PCM composites can readily absorb solar light with various intensities to transfer the thermal energy. PCM composite constructed PN junction thermoelectric power generator (PN TEG) can produce electrical energy according to the light-on/-off process, where the thermoelectric energy harvesting efficiencies are 67.92 and 41.72%, respectively. To demonstrate the experimental results, the finite numerical calculation method is utilized.