Plasma Electrochemistry for Electrolytic Processing Seminar

In the conventional picture of electrolytic processing, two metal electrodes are submerged into a electrolyte solution and an applied potential drives redox reactions at the cathode and anode,respectively. Plasma electrochemistry, also called glow discharge electrolysis, changes this convention by replacing one or both of the solid electrodes with a gas discharge. As such, reduction and oxidation reactions are no longer mediated by a solid/liquid interface but by a gaseous/liquid interface, requiring that free charges traverse from the gas to liquid and vice versa. For the past several years, we have been studying a plasma cathode configuration, where an atmospheric-pressure microhollow cathode glow discharge replaces the cathode in an electrolytic cell. In this configuration, free gaseous electrons in the plasma must be injected into the solution phase to initiate reduction reactions at the “cathode”. In this talk, I will overview our efforts at understanding and using this charge transfer process for electroylitc processing. The discussion will include using plasma electrochemistry systems for the production of nanomaterials and carbon dioxide (CO2) processing, and well as our efforts to understand electron injection from the plasma phase into the liquid phase and the ensuing electron-driven chemistry. I will cover both indirect measurements of long-lived products and more precise direct measurements of the electrons in the solution in a solvated state. In particular, I will present how the chemistry in these systems perhaps more closely reflects radiation chemistry than electrochemistry. Finally, I will discuss some new modeling results that aim to resolve some unanswered questions in this field, while perhaps raising new questions that require further study.