Electrochemical Production of Oxalate and Formate from CO2 by Solvated Electrons Produced Using an Atmospheric-Pressure Plasma

In this work, we use an atmospheric-pressure plasma in argon as a cathode to electrochemically reduce carbon dioxide in aqueous solution. Using optical absorption spectroscopy, we directly show that solvated electrons reduce CO2(aq) to form the carboxyl radical anion CO2- ((aq)), and the reaction obeys 3D bulk reaction kinetics similar to those measured in radiolysis experiments. We then use liquid ion chromatography to show that the CO2- ((aq)) intermediate ultimately reacts to produce oxalate and formate. The overall faradaic efficiency of the reaction is close to 10% for a CO2(aq) concentration of 34 mM. However, given the known reaction kinetics of solvated electrons, this efficiency should approach 100% as the concentration of CO2(aq) is increased. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.