Influence of Plasma-Generated Species on the Faradaic Efficiency of Plasma-Liquid Systems

Plasma-liquid interactions have drawn the attention of the plasma community due to the promise of wide-range of applications including nanoparticle synthesis, medical therapeutics, and wastewater treatment. The chemical pathways behind these applications are often initiated by highly reactive species such as the solvated electron (e-
aq
), and the hydroxyl radical (OH). However, there is a lack of understanding in their relative concentrations, penetration depth, and effective reaction rates, and how they affect the chemistry in the liquid phase; often, properties are drawn from different systems, without a thorough understanding of their transferability. In this work, we study the reduction of ferricyanide (Fe(CN)6
³
-) in an electrochemical cell by an argon plasma. This system was used to analyze the concentrations of e-
aq
and OH, the penetration depth of e-
aq
, as well as the role that OH plays in liquid chemistry under an inert atmosphere. Additionally, effective reaction times are calculated and their significance in chemical reactions and applications is explored.