Organic thermoelectric (TE) materials are very attractive due to easy processing, material abundance, and environmentally-benign characteristics, but their potential is significantly restricted by the inferior thermoelectric properties. In this work, noncovalently functionalized graphene with fullerene by π-π stacking in a liquid-liquid interface was integrated into poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate). Graphene helps to improve electrical conductivity while fullerene enhances the Seebeck coefficient and hinders thermal conductivity, resulting in the synergistic effect on enhancing thermoelectric properties. With the integration of nanohybrids, the electrical conductivity increased from ~10000 to ~70000 S/m, the thermal conductivity changed from 0.2 to 2 W·K−1m−1 while the Seebeck coefficient was enhanced by around 4-fold. As a result, nanohybrids-based polymer composites demonstrated the figure of merit (ZT) as high as 6.7 × 10−2, indicating an enhancement of more than one order of magnitude in comparison to single-phase filler-based polymer composites with ZT at the level of 10−3.
Fullerene-functionalized graphene shows a hierarchical structure, and is promising for many potential applications. In this paper, a new method is presented to synthesize such a novel nanostructure. Graphite flakes were intercalated to graphite oxide, and then functionalized with zero-dimensional fullerene nanocrystals. The resultant compounds were characterized by FT-IR spectroscopy, UV–Vis spectroscopy, atomic force microscopy, and transmission electron microscopy. The characterization results confirmed that fullerene crystals were successfully attached onto the single-layer graphene sheets and significantly facilitated the exfoliation of graphite to monolayer graphene. The fullerene grafted on the graphene surface serves as a space impediment to prevent the re-stacking of exfoliated graphene sheets. This attempt provides an effective route for large-scale exfoliation and functionalization of monolayer graphene, and is expected to significantly facilitate the application of graphene in the electronic devices, energy storage, and functional materials.
We report on the enhancement and possible control of both laser ignition and burn rates of Nitrocellulose (NC) microfilms when doped with graphene oxide (GO). A Nd:YAG (1064 nm, 20 ns) laser is used to ignite GO-doped NC films at low temperatures. The effect of GO on the doping concentration of the activation energies of laser ignition and thermal stability of the NC films is studied. The activation energy of laser ignition decreases with increasing GO/NC weight ratio and attains a constant value with higher concentrations. This behavior is accompanied by an increase in the thermal stability.