Ratio Oxalate to Formate Tuned by pH During CO2 Reduction Driven by Solvated Electron at the Electrified Plasma/Liquid Interface

Abstract

The electrified plasma/liquid interface (PLI) promotes the CO2 reduction (CO2R) with a spectrum of products distinct from that of other electrochemical platforms. However, the lack of fundamental understanding greatly disables the preconize of its industrial potential. In particular, the inaccurate reaction mechanism of CO2R via electrified PLI brings imprecision on the theoretical predictions of selectivities in acid electrolytes. For this reason, the present work categorically considers the proton as a reactant and the proton concentration as an essential parameter for the dynamical model describing the CO2RR via electrified PLI. Two new routes toward formic acid production are proposed, namely, the disproportionation-like and radical cross-combination reactions. Both were capable of significantly reproducing the feature observed with real-life experiments for the final product proportions; however, the cross-combination reaction adjusts the most. With these reasonably assertive mechanisms of CO2RR in acid media, it was possible to predict that an extremely acid pH (~ 1) is required to attain concentration ratio oxalate to formate equal to 50 to 50 and 10 to 90 when considering the disproportionation-like and cross-combination reaction, respectively.