Perspectives on Plasmas in Contact with Liquids for Chemical Processing and Materials Synthesis

Abstract

Plasmas and gas discharges in contact with liquids have played an important role in the history of chemical processing and scientific inquiry, leading to the discoveries of elements such as argon and compounds such as ozone. Recently-developed atmospheric-pressure plasma sources have renewed the study of plasma–liquid systems with applications in chemical processing, materials synthesis, and chemical analysis. In many cases, these approaches utilize glow discharge electrolysis configurations where a DC plasma replaces one of the metal electrodes in a standard electrolytic cell. These configurations have been used to great effect for the synthesis of various nanomaterials and more recently, in the processing of carbon dioxide. In this work, we overview recent developments using plasmas as electrodes in electrolytic cells for chemical processing, drawing parallels to conventional electrochemistry and electrocatalysis. In particular, we highlight recent studies on the fundamental chemical processes at the plasma–liquid interface, including new interfacial measurement techniques used to probe charge transfer. We conclude with an overview of opportunities for these configurations in the future and highlight the need for further fundamental study.