Jump to main content
Jump to site search

Issue 10, 2016
Previous Article Next Article

The effect of electrolyte composition on the electroreduction of CO2 to CO on Ag based gas diffusion electrodes

Author affiliations

Abstract

The electroreduction of CO2 to C1–C2 chemicals can be a potential strategy for utilizing CO2 as a carbon feedstock. In this work, we investigate the effect of electrolytes on the electroreduction of CO2 to CO on Ag based gas diffusion electrodes. Electrolyte concentration was found to play a major role in the process for the electrolytes (KOH, KCl, and KHCO3) studied here. Several fold improvements in partial current densities of CO (jCO) were observed on moving from 0.5 M to 3.0 M electrolyte solution independent of the nature of the anion. jCO values as high as 440 mA cm−2 with an energy efficiency (EE) of ≈ 42% and 230 mA cm−2 with EE ≈ 54% were observed when using 3.0 M KOH. Electrochemical impedance spectroscopy showed that both the charge transfer resistance (Rct) and the cell resistance (Rcell) decreased on moving from a 0.5 M to a 3.0 M KOH electrolyte. Anions were found to play an important role with respect to reducing the onset potential of CO in the order OH (−0.13 V vs. RHE) < HCO3 (−0.46 V vs. RHE) < Cl (−0.60 V vs. RHE). A decrease in Rct upon increasing electrolyte concentration and the effect of anions on the cathode can be explained by an interplay of different interactions in the electrical double layer that can either stabilize or destabilize the rate limiting CO2˙ radical. EMIM based ionic liquids and 1 : 2 choline Cl urea based deep eutectic solvents (DESs) have been used for CO2 capture but exhibit low conductivity. Here, we investigate if the addition of KCl to such solutions can improve conductivity and hence jCO. Electrolytes containing KCl in combination with EMIM Cl, choline Cl, or DESs showed a two to three fold improvement in jCO in comparison to those without KCl. Using such mixtures can be a strategy for integrating the process of CO2 capture with CO2 conversion.

Graphical abstract: The effect of electrolyte composition on the electroreduction of CO2 to CO on Ag based gas diffusion electrodes

Back to tab navigation

Supplementary files

Publication details

The article was received on 21 Sep 2015, accepted on 20 Nov 2015 and first published on 23 Nov 2015


Article type: Paper
DOI: 10.1039/C5CP05665A
Author version
available:
Download author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2016,18, 7075-7084
  •   Request permissions

    The effect of electrolyte composition on the electroreduction of CO2 to CO on Ag based gas diffusion electrodes

    S. Verma, X. Lu, S. Ma, R. I. Masel and P. J. A. Kenis, Phys. Chem. Chem. Phys., 2016, 18, 7075
    DOI: 10.1039/C5CP05665A

Search articles by author

Spotlight

Advertisements