(Invited) Electrodeless Organic Electrosynthesis By Plasma-Liquid Interface

Abstract

The plasma-liquid interface can promote selective redox reactions involving organic molecules without the need for solid electrodes. More specifically, our group’s work on model organic compounds has revealed that selective reduction occurs near the surface of water in contact with an RF plasma jet generated using helium or argon as working gas, for positions located near the centerline of the impinging free jet. The complementary oxidation half reaction occurs further away from the centerline, and the products of reduction and oxidation can be isolated by placing a semipermeable membrane between the reduction and oxidation zones, which are termed electrodeless cathode and anode respectively. The reduction potential in the liquid near the surface at the plasma jet centerline can be tuned by changing the plasma parameters. Correlations between reduction potential and plasma parameters, specifically electron density and temperature as characterized by Thomson scattering, will be presented and a simple model proposed to theoretically connect the two. Finally, envisioned applications for this unique type of electrodeless organic electrosynthesis will be discussed in the fields of water quality, renewable carbon utilization, and pharmaceuticals. The work described in this presentation is collaborative between research groups at Washington University in Saint Louis, Princeton Plasma Physics Laboratory, and the University of Michigan; and was supported by the Department of Energy under award DE-SC0020352, the Princeton Collaborative Low Temperature Plasma Research Facility (PCRF), and the National Science Foundation through grant CBET-2033714.