Ponente
Descripción
Carbon nanostructures (CNS) are materials with varied applications in electronics, medicine and industry. Submerged Arc Discharge in Water (SADW) is one of the most widespread methods for the synthesis of CNS but it involves complex processes of nucleation and growth that are influenced by factors such as arc current, electric field, mechanical stability and temperature quenching. In this study, we synthesized multiwall carbon nanotubes (MWCNTs), carbon onions (CNOs), graphene oxide (GO), and carbon quantum dots (CQDs) using the SADW method at arc currents of 30, 40 and 50A and characterized their structure and properties using various techniques such as Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). The increase in current causes an increase in the crystallite sizes La and in the presence of vacancy-type defects. It was also found that the synthesis current has a strong effect on the order and orientation of the CNS graphitic layers. For the CNOs and MWCNTs, an increase in the current produces an increase in the turbostratic character and the presence of folds and curvatures. Behavior contrary to that of GOs and CQDs, which experience a decrease in this type of disorder. This is because SADW method involves not only homogeneous nucleation of carbon vapor but also exfoliation of graphite and graphene fragments that contribute to the formation of various nanostructures like polyhedral CNOs and impurities like Large Polyhedral Particles (LPP). These exfoliated structures also react with water vapor they form the GOs and CQDs. The study provides a general model for the nucleation and growth mechanisms of carbon nanostructures in the SADW method and offers guidelines for the optimal synthesis.
