The Arc Current Effect on the Structure and Resistance of Nanoparticles

Abstract

This study investigates the influence of arc discharge current on the morphological, electrical, and plasma characteristics of carbon nanoparticles synthesized via submerged plasma arc discharge in deionized water. Arc currents of 40 A, 70 A, and 100 A were applied to graphite electrodes, and the resulting nanostructures were characterized using transmission electron microscopy (TEM), current-voltage (I–V) electrical measurements, and ionization energy analysis derived from time-resolved arc current behavior. The findings demonstrate that increasing the arc current significantly alters the morphology of the carbon products, transitioning from predominantly spherical carbon nano-onions (CNOs) at 40 A to multi-walled carbon nanotubes (MWCNTs) at 100 A. Concurrently, I–V characterization reveals an increasing trend in electrical resistance, rising from ~20 kΩ at 40 A to ~90 kΩ at 100 A, suggesting a strong correlation between nanostructure geometry and macroscopic conductivity. Ionization energy distributions derived from arc current dynamics further reveal a transition from continuous energy profiles at 40 A to highly discrete peaks at 100 A, indicating a shift in plasma species and energy transfer mechanisms. These discrete ionization profiles at higher currents are proposed to facilitate anisotropic carbon growth, favoring CNT formation through directed energy delivery and ion-assisted crystallization. This work elucidates the coupled roles of arc current, plasma behavior, and nanoparticle morphology in determining the structure and electrical properties of carbon nanomaterials synthesized via arc discharge.