Probing Electrochemical Reactions at a Plasma-Liquid Interface
Final rept. 9 Jun 2014-8 Mar 2015
NOTRE DAME UNIV IN
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The goal of this ARO STIR was to conduct preliminary investigations toward understanding electrochemical reactions promoted by microplasmas at the interface of aqueous solutions. We developed a novel total internal reflection absorption spectroscopy experiment directly at the plasma-solution interface leading to the first ever measurement and detection of plasma-generated solvated electrons. We found that the plasma-liquid interfacial environment produces different solvated electron behavior than other approaches to generating solvated electrons e.g., pulse radiolysis including a blue-shifted and narrower absorption spectrum as well as different reaction rate coefficients. We attribute these differences to the electrochemical configuration of the plasma-solution system such as the strong electric field in the Debye layer of the plasma-liquid interface. We also developed a method to precipitate, separate, and weigh solid silver produced by plasma-initiated electrolytical reduction of silver cations Ag, leading to the first estimates of the efficiency 80 for the reduction of Ag by a plasma process. These results reveal that inherent competing chemical pathways must be accounted for when using plasmasolution systems, as effects such as second order recombination in the liquid phase or electron scavenging in the gas phase compete with direct cation reduction.
- Physical Chemistry