Synthesis of chain-like carbon nano-onions by a flame assisted pyrolysis technique using different collecting plates

A flame assisted pyrolysis method was used to synthesize chain-like graphitic carbon nano-onions from ghee oil as a carbon precursor (CNOs; ca. d <= 60 nm), collected over both brass and glass collecting plates. While the gram scale yields of CNOs produced from both procedures were similar, the carbons nanomaterials displayed different chemical and structural morphological properties. For instance, high magnification TEM micrographs revealed that the produced CNOs were quasi-spherical nanomaterials with varying average diameters, i.e. ca. 37 +/- 3.3 nm (from brass) and ca. 55 +/- 4.1 nm (from glass). The BET analysis showed that the surface areas of the pristine CNOs (pCNOs) were similar for both materials (brass, similar to 59 m(2)/g; glass, similar to 53 m(2)/g). The thermal analysis data revealed that pCNOs product collected using the brass collecting plate (BCP) was different from those produced using a glass collecting plate (GCP). Furthermore, the thermal treatment of pCNOs produced from both collecting plates (at 900 degrees C, under Ar) resulted in different TGA data in which the CNOs produced using a GCP showed broader first order derivative peaks than those collected using a BCP. Raman analysis showed a lower defect density ratio (I-D/I-G, ca. similar to 0.89) for the pCNOs synthesized using a BCP, indicating that they were more graphitic than those obtained using a GCP (ca. similar to 1.00). It is thus clear that control of the thermal properties of the collector device plays an important role is determining the characteristics of CNOs.