Electrochemical characterization of electrolyte purity for CO2 reduction studies

In this work, we put forward a simple electrochemical approach to conveniently determine the purity of the electrolyte solution which improves the reproducibility and reliability of electrochemical CO2 reduction data such that experimental outcomes can be readily compared across research groups. The method uses a polycrystalline Au electrode as a probe to detect electrolyte impurities that can readily be adsorbed to surfaces even when ultrahigh-purity (99.999%) commercial chemicals are used as received. Herein, we show how the extent of trace contamination alters the measured activity during CO2 reduction and demonstrate electrochemical methods to capture these trace contaminants, such that CO2 reduction activity can be reproduced reliably.