The Electrified Plasma/Liquid Interface as a Platform for Highly Efficient CO₂ Electroreduction to Oxalate

The electrified plasma/liquid interface (PLI) serves as a unique electrosynthesis platform for the CO 2 reduction reaction (CO2RR). This work aims to highlight the potential of such an electrosynthesis platform. For this reason, the CO2RR mechanism is postulated by considering the volume beneath the electrified PLI, termed the nanoreactor, and its chemical dynamics are evaluated by computational experiments. The commonalities noted between the reactant species in the electrified PLI and the field of radiolysis help to postulate the mechanism. The chemical dynamics not only explain the preferential synthesis of oxalate due to the promotion of a carbon–carbon bond by the high local concentration of the carboxyl radical anion (CO 2 –• (aq)) but also elucidate the depletion of the dissolved CO 2 (CO 2 (aq)) at the nanoreactor within the initial 0.043 s of continuous discharge, with hydrogen being produced only afterward. This work estimates ca. 98% CO2RR efficiency; of this, 97% is selective to oxalate if a flow cell is used as the electrolyte flow refills the CO 2 (aq) content into the nanoreactor. This study postulates a radiolysis-based mechanism for CO2RR via the electrified PLI, which provides insight in order to develop processes in the field of plasma electrochemistry.