In situ synthesis of nitrogen-doped graphene nanoflakes using non-thermal arc plasma

Abstract

A non-thermal arc plasma process was developed for the in situ synthesis of nitrogen-doped graphene nanoflakes (N-GNFs), which used CH4/C2H4 as the carbon precursor and N2 as both the plasma gas and nitrogen precursor. N-GNFs with nitrogen-doping levels of 1%–3% (atomic percentage) were fabricated in the pressure range of 100–400 kPa. The effect of pressure and carbon precursor on product characteristics was investigated. It was found that a higher pressure favored the N-GNFs with high nitrogen-doping levels and high yield but it aggravated the curling of nanoflakes and reduced the nanoflake size, resulting in increased defects and a lower specific surface area. The nitrogen configuration was mainly determined by the carbon precursor, where pyrrolic N predominated in the N-GNFs synthesized from CH4, while the level of graphitic N was markedly higher when C2H4 was used. Correlations between the product properties and experimental parameters indicate that the variation of the plasma parameters induced by pressure changes and the hydrogen-poor/rich environment (depending on the carbon precursor) were the main factors affecting the product characteristics.