ae9b01736_si_001.pdf (551 kB)
One-Minute Joule Annealing Enhances the Thermoelectric Properties of Carbon Nanotube Yarns via the Formation of Graphene at the Interface
journal contribution
posted on 2019-10-17, 14:38 authored by Masaki Hada, Taisuke Hasegawa, Hirotaka Inoue, Makito Takagi, Kazuki Omoto, Daiki Chujo, Shogo Iemoto, Taihei Kuroda, Taiga Morimoto, Takuma Hayashi, Toru Iijima, Tomoharu Tokunaga, Naoshi Ikeda, Kazuhiro Fujimori, Chihiro Itoh, Takeshi Nishikawa, Yoshifumi Yamashita, Toshihiko Kiwa, Shin-ya Koshihara, Satoshi Maeda, Yasuhiko HayashiInterfaces
in nanocarbon materials are highly important, as they determine the
properties of carbon-based devices. In terms of carrier and thermal
transport properties, the interfacial features are often more important
than the intrinsic characteristics. Herein, we describe how 1 min
Joule annealing of carbon nanotube (CNT) yarns can convert the interfacial
amorphous carbon into graphene fragments. After 1 min Joule annealing,
we have obtained multiwalled CNT yarns with extremely high Seebeck
coefficients (±100 μV/K) and high thermoelectric power
factor (400 and 1000 μW/mK2) at room temperature,
both with or without polyethylenimine doping. Theoretical simulations
and experimental measurements helped to determine the optimal annealing
conditions in terms of a rapid transformation of the interfacial amorphous carbon between the bundled
CNTs in the yarn into graphene fragments at ∼2000 K. The present
approach represents significant progress in energy materials science,
as it provides a guiding principle for the design of interfaces in
nanocarbon materials with potential applications in energy-harvesting
systems.