Purification and Nitrogen Doping of Nanothin Exfoliated Graphite Through RF Thermal Plasma Treatment

Byung-Koo Son; Kyu-Hang Lee; Tae-Hee Kim; Myung-Sun Shin; Sun-Yong Choi; Guangsup Cho

doi:10.3390/nano9070995

Purification and Nitrogen Doping of Nanothin Exfoliated Graphite Through RF Thermal Plasma Treatment

Nanomaterials (Basel). 2019 Jul 10;9(7):995. doi: 10.3390/nano9070995.

Authors

Byung-Koo Son^{1

2}, Kyu-Hang Lee^{1

2}, Tae-Hee Kim³, Myung-Sun Shin^{1

2}, Sun-Yong Choi², Guangsup Cho⁴

Affiliations

¹ Department of Electrical and Biological Physics, Kwangwoon University, Seoul 01897, Korea.
² Division of Plasma Convergence R&BD, Cheorwon Plasma Research Institute, Cheorwon 24047, Korea.
³ Institute for Nuclear Science and Technology, Jeju National University, Jeju 63243, Korea.
⁴ Department of Electrical and Biological Physics, Kwangwoon University, Seoul 01897, Korea. gscho@kw.ac.kr.

Abstract

A mixture of nanothin exfoliated (NTE) graphite and urea (CO(NH₂)₂) powder was treated with radio frequency (RF) thermal plasma to achieve in situ purification and nitrogen doping of NTE graphite using the high-temperature flame of the RF plasma. Reactive species such as NH₃, NH₂, and HCNO generated by the thermolysis of urea play an important role in the purification and nitrogen doping of NTE graphite. The nitrogen content of NTE graphite subjected to plasma treatment increased by 5 times compared with that of raw NTE graphite. Three types of nitrogen species, namely, quaternary N, pyridinic N, and pyrrolic N, were observed after N doping with plasma treatment. The sheet resistance of N-doped NTE graphite reduced to 12-21% compared to that of the untreated NTE graphite, with the corresponding resistivity being ~7 × 10^-6 Ω m.

Keywords: N doping; RF thermal plasma; nanothin exfoliated graphite; nitrogen-doped graphite; purification.