Observation of novel carbon nanocorals during the synthesis of graphene and investigations on their composition, morphological and structural properties

Novel carbon nanocorals (CNCs) are observed during the synthesis of graphene on copper substrates by thermal chemical vapor deposition, using precursor gas acetylene (C₂H₂) and carrier gas argon (Ar). CNCs have unique structure and investigations are carried out on structural and elemental compositions by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES), energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), and high resolution transmission electron microscopy (HRTEM). The graphitic nature of the CNCs is evident from characteristic D, G, and 2D bands obtained from Raman spectrum. Elemental composition analysis by XPS shows presence of sp² and sp³ hybridized carbon whereas XAES quantifies percentage of sp² and sp³ hybridized carbon. FESEM micrographs show a uniform distribution of densely packed CNCs throughout the sample, and formation of groups of CNCs with distinct contours on the surface. The cross-sectional FESEM shows stacking of large number of graphene layers with dendrites. HRTEM analysis further supports observations of FESEM and elaborates structural morphology of the CNCs. Synthesis, characterization and analysis of the properties of carbon nanocorals are reported here, for the first time.