Title: Effect of Competing Oxidizing Reactions and Transport Limitation on the Faradaic Efficiency in Plasma Electrolysis

Abstract

Plasma electrolysis, where a solid electrode in an electrolytic cell is replaced by a plasma (or gas discharge), differs from conventional electrolysis by not being dictated by the surface characteristics of an electrode, but by the chemical species injected into the solution from the plasma. Reduction in a plasma cathode configuration occurs mostly by plasma-injected solvated electrons (e-aq), which may engage in side reactions, such as the second order recombination of e-aq, that ultimately reduce the faradaic efficiency for the production of a desired product. In this work, we show that the depletion of reactants at the plasma-liquid interface due to insufficient transport can reduce the predicted faradaic efficiency for a plasma cathode at low concentrations. Measurements of the faradaic efficiency using the dissociative electron attachment to chloroacetate and the ferri/ferrocyanide redox couple confirm this behavior. The effect of other mechanisms on the faradaic efficiency, such as competing oxidation reactions with the hydroxyl radical, are also evaluated and found to be far less significant. Unlike conventional electrolysis, stirring the solution does not increase the faradaic efficiency, but increasing the species concentration does.

Authors:

Delgado, Hernan E. ;

• Search DOE PAGES for author "Delgado, Hernan E."
• Search DOE PAGES for ORCID "0000-0001-8969-6523"

Radomsky, Rebecca C.; Martin, Daniel C.; Bartels, David M. ;

• Search DOE PAGES for author "Bartels, David M."
• Search DOE PAGES for ORCID "0000-0003-0552-3110"

Rumbach, Paul ;

• Search DOE PAGES for author "Rumbach, Paul"
• Search DOE PAGES for ORCID "0000-0002-0154-3045"

Go, David B.

• Search DOE PAGES for author "Go, David B."
• Search DOE PAGES for ORCID "0000-0001-8948-1442"

Publication Date:

Tue Apr 09 00:00:00 EDT 2019

Research Org.:

University of Notre Dame, IN (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1505890

Alternate Identifier(s):

OSTI ID: 1609180

Grant/Contract Number:  

FC02-04ER1553; FC02-04ER15533

Resource Type:

Published Article

Journal Name:

Journal of the Electrochemical Society

Additional Journal Information:

Journal Name: Journal of the Electrochemical Society Journal Volume: 166 Journal Issue: 6; Journal ID: ISSN 0013-4651

Publisher:

IOP Publishing - The Electrochemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Electrochemistry; Materials Science