Controlled regulation of the transformation of carbon nanomaterials under H2 mixture atmosphere by arc plasma.

[Display omitted] • H 2 regulates carbon materials structural transformation and N doping by arc plasma. • Morphological control ability is in order of H 2 > N 2 > Ar. • C-H amounts lead to structural transformation by stable structure from curved growth. Hydrogen plays a pivotal role in carbon nanomaterials synthesis by arc plasma. However, the effect of hydrogen on morphological regulation of carbon nanomaterials has received little attention. In this paper, carbon nanomaterials synthesized under mixed H 2 /Ar, H 2 /N 2 , and Ar/N 2 atmospheres with different ratios were investigated in detail to tackle the issue. Graphene, carbon nanocages, polyhedral graphite particles, amorphous carbon nanoballs, and carbon nanohorns underwent structural transformation as hydrogen content reduced. As a result of varying hydrogen concentration, the number of C-H bond sites at the edge of graphene islands differed, leading to the structural transformation of carbon nanomaterials originating from the formation of various types of precursors. Meanwhile, X-ray photoelectron spectroscopy results revealed that hydrogen impeded nitrogen doping because it tended to bond with electronegative nitrogen. Moreover, morphology control capability followed the order of H 2 > N 2 > Ar during the preparation of carbon nanomaterials through arc plasma under a mixed atmosphere. [ABSTRACT FROM AUTHOR]