纳米石墨纤维的高热电性能
High thermoelectric performance of graphite nanofibers
摘要：
石墨纳米纤维（GNF）已被证明是一种很有前途的材料，用于电子设备中的储氢和热管理。在这里，通过第一性原理和输运模拟，我们表明，GNF也可以是一个很好的热电应用材料，这要归功于层间弱范德华相互作用，诱导低热导率和台阶状的形状，在电子传输与微间隙，这是必要的成分，以实现高热电性能。该研究揭示了石墨层垂直于纤维轴的片状形式的GNF可以表现出优异的热电性能，在直径为0.5 nm的纤维中，ZT值达到3.55，对于直径为1.1 nm的纤维，ZT值达到1.1。有趣的是，通过引入14C同位素掺杂，ZT甚至可以提高到5以上，如果我们考虑有限声子平均自由程的影响，则可以提高到8以上，这表明了GNF的惊人的热电潜力。
英文摘要：
Graphite nanofibers (GNFs) have been demonstrated to be a promising material for hydrogen storage and heat management in electronic devices. Here, by means of first-principles and transport simulations, we show that GNFs can also be an excellent material for thermoelectric applications thanks to the interlayer weak van der Waals interaction that induces low thermal conductance and a step-like shape in the electronic transmission with mini-gaps, which are necessary ingredients to achieve high thermoelectric performance. This study unveils that the platelet form of GNFs in which graphite layers are perpendicular to the fiber axis can exhibit outstanding thermoelectric properties with a figure of merit ZT reaching 3.55 in a 0.5 nm diameter fiber and 1.1 for a 1.1 nm diameter one. Interestingly, by introducing 14C isotope doping, ZT can even be enhanced up to more than 5, and more than 8 if we include the effect of finite phonon mean-free path, which demonstrates the amazing thermoelectric potential of GNFs.
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