DC arc discharge with a liquid metal anode in hydrocarbon atmosphere*

A direct current (DC) arc discharge is a widely used method for production of metal nanoparticles, core-shell particles, and carbon nanotubes [1]. Here, we deployed an industrially relevant and sustainable approach of the DC arc between metal electrodes in methane atmosphere [2]. Iron nanoparticles were produced by the evaporation of the iron anode, while methane served as a carbon source. Obtained nanomaterials, mainly Fe@C core-shell nanoparticles and carbon nanotubes, were comprehensively characterized ex situ.

The arc and its behavior were investigated using high-speed imaging, spatially-averaged broadband and spatially-/spectrally-resolved optical emission spectroscopy, and thermal imaging of electrodes. The efforts on improving arc stability, which is important for steady-state synthesis conditions [3], will be presented, such as the choice of electrodes material and design, and chemical gas composition. For example, high speed imaging and  I–V curves showed that the metal arc in pure argon is more stable relative to the metal arc in a hydrocarbon-containing gas and than the carbon arc [3].

The discussion will also focus on the peculiar aspects of iron ablation in DC arcs with various inert gases and the challenges associated with measuring the ablation in a hydrocarbon environment due to carburization.

 

[1] C. Journet et al., Nature 388 (1997) 756–758

[2] Predtechenskiy, US patent 2020/0239316 A1, 2020

[3] S. Gershman and Y. Raitses,  J. Phys. D. Appl. Phys. 49, 345201 (2016)