Electrochemical CO₂ Reduction in the Presence of Impurities: Influences and Mitigation Strategies

Abstract

The electrochemical conversion of waste CO 2 into useful fuels and chemical products is a promising approach to reduce CO 2 emissions; however, several challenges still remain to be addressed. Thus far, most CO 2 reduction studies use pure CO 2 as the gas reactant, but CO 2 emissions typically contain a number of gas impurities, such as nitrogen oxides, oxygen gas, and sulfur oxides. Gas impurities in CO 2 can pose a significant obstacle for efficient CO 2 electrolysis because they can influence the reaction and catalyst. This Minireview highlights early examples of CO 2 reduction studies using mixed-gas feeds, explores strategies to sustain CO 2 reduction in the presence of gas impurities, and discusses their implications for future progress in this emerging field.

Stability Issues in Electrochemical CO2Reduction: Recent Advances in Fundamental Understanding and Design Strategies

“…These impurities include trace amounts of heavy metal ions in catalysts or electrolyte, organic substances in water, and impurities in gaseous CO 2 . [101] Early works by Hori et al indicated that trace metal ions in the electrolyte (such as Fe 2+ , Zn 2+ ) would be deposited on Cu surface under cathodic potential to induce the electrode deactivation. [102,103] The use of Ag/AgCl reference electrode may bring Ag contamination.…”

Advancements in Environmentally Sustainable Technologies for Ethylene Production

“…The limited concentration (10−15%) of CO 2 in the flue gas restricts ethylene production due to mass-transfer limitation, which does not allow the reactor to achieve a current density >0.3 μA/cm 2 . Harmon et al 190 investigated electrochemical CO 2 reduction, its susceptibility to various impurities, and potential mitigation strategies. Flue gas composition significantly influenced the catalytic activity and selectivity of the electrochemically active CO 2 reduction process.…”

Pure and Metal‐confining Carbon Nanotubes through Electrochemical Reduction of Carbon Dioxide in Ca‐based Molten Salts

“…Impurities in industrial CO 2 -containing flue gas generally impose negative effects on CO 2 conversion. [17] Metal oxides (MO x ) are the main dusts in industrial CO 2 -containing flue gas. [18] Elimination of MO x dusts from industrial flue gas becomes mandatory prior to be piped into membrane CO 2 electrolyzers.…”