Analysis of Mass Flows and Membrane Crossover in CO2 Reduction at High Current Densities in a MEA-Type Electrolyzer

Gastón O Larrazábal, Patrick Strøm-Hansen, Jens P. Heli, Kevin Zeiter, Kasper T. Therkildsen, Ib Chorkendorff, Brian Seger*

*Corresponding author for this work

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Abstract

Cell designs that integrate membrane-electrode assemblies (MEAs) with highly selective catalysts are a promising route to reduce ohmic losses and achieve high energy efficiency in CO2 reduction at industrially relevant current densities. In this work, porous silver filtration membranes are demonstrated as simple and efficient gas-diffusion electrodes for CO2 reduction to CO at high current densities in a MEA-type device. A partial current density for CO of up to ca. 200 mA cm-2 was achieved at a cell voltage of ca. 3.3 V, in tandem with minimal H2 production. However, the analysis of cathodic and anodic outlet streams revealed that CO2 crossover across the AEM, mostly in the form of CO32- but partially as HCOO- generated over the cathode, actually exceeds the amount of CO2 converted to the target product, resulting in a poor utilization of the reactant and in the early onset of mass transfer limitations. In addition, COcrossover leads to non-stoichiometric decrease of the outlet flow rate from the cathodic compartment that can lead to a substantial overestimation of catalytic performance if the inlet flow rate of CO2 is used as reference for calculating partial current densities and Faradaic efficiencies. The results of this work highlight the importance of carrying out a carbon balance, in addition to traditional measurements of activity and selectivity, to adequately assess the performance of CO2 reduction devices at high current densities, and inform future efforts aimed at mitigating membrane crossover in MEA-type electrolyzers for CO2 reduction.
Original languageEnglish
JournalACS Applied Materials and Interfaces
Volume11
Issue number44
Pages (from-to)41281-41288
Number of pages8
ISSN1944-8244
DOIs
Publication statusPublished - 2019

Keywords

  • Electrocatalysis
  • CO2 reduction
  • Silver
  • Anion-exchange membrane
  • Membrane-electrolyde assembly
  • Electrolyzer

Cite this

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title = "Analysis of Mass Flows and Membrane Crossover in CO2 Reduction at High Current Densities in a MEA-Type Electrolyzer",
abstract = "Cell designs that integrate membrane-electrode assemblies (MEAs) with highly selective catalysts are a promising route to reduce ohmic losses and achieve high energy efficiency in CO2 reduction at industrially relevant current densities. In this work, porous silver filtration membranes are demonstrated as simple and efficient gas-diffusion electrodes for CO2 reduction to CO at high current densities in a MEA-type device. A partial current density for CO of up to ca. 200 mA cm-2 was achieved at a cell voltage of ca. 3.3 V, in tandem with minimal H2 production. However, the analysis of cathodic and anodic outlet streams revealed that CO2 crossover across the AEM, mostly in the form of CO32- but partially as HCOO- generated over the cathode, actually exceeds the amount of CO2 converted to the target product, resulting in a poor utilization of the reactant and in the early onset of mass transfer limitations. In addition, CO2 crossover leads to non-stoichiometric decrease of the outlet flow rate from the cathodic compartment that can lead to a substantial overestimation of catalytic performance if the inlet flow rate of CO2 is used as reference for calculating partial current densities and Faradaic efficiencies. The results of this work highlight the importance of carrying out a carbon balance, in addition to traditional measurements of activity and selectivity, to adequately assess the performance of CO2 reduction devices at high current densities, and inform future efforts aimed at mitigating membrane crossover in MEA-type electrolyzers for CO2 reduction.",
keywords = "Electrocatalysis, CO2 reduction, Silver, Anion-exchange membrane, Membrane-electrolyde assembly, Electrolyzer",
author = "Larraz{\'a}bal, {Gast{\'o}n O} and Patrick Str{\o}m-Hansen and Heli, {Jens P.} and Kevin Zeiter and Therkildsen, {Kasper T.} and Ib Chorkendorff and Brian Seger",
year = "2019",
doi = "10.1021/acsami.9b13081",
language = "English",
volume = "11",
pages = "41281--41288",
journal = "A C S Applied Materials and Interfaces",
issn = "1944-8244",
publisher = "American Chemical Society",
number = "44",

}

Analysis of Mass Flows and Membrane Crossover in CO2 Reduction at High Current Densities in a MEA-Type Electrolyzer. / Larrazábal, Gastón O; Strøm-Hansen, Patrick; Heli, Jens P.; Zeiter, Kevin; Therkildsen, Kasper T.; Chorkendorff, Ib; Seger, Brian.

In: ACS Applied Materials and Interfaces, Vol. 11, No. 44, 2019, p. 41281-41288.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Analysis of Mass Flows and Membrane Crossover in CO2 Reduction at High Current Densities in a MEA-Type Electrolyzer

AU - Larrazábal, Gastón O

AU - Strøm-Hansen, Patrick

AU - Heli, Jens P.

AU - Zeiter, Kevin

AU - Therkildsen, Kasper T.

AU - Chorkendorff, Ib

AU - Seger, Brian

PY - 2019

Y1 - 2019

N2 - Cell designs that integrate membrane-electrode assemblies (MEAs) with highly selective catalysts are a promising route to reduce ohmic losses and achieve high energy efficiency in CO2 reduction at industrially relevant current densities. In this work, porous silver filtration membranes are demonstrated as simple and efficient gas-diffusion electrodes for CO2 reduction to CO at high current densities in a MEA-type device. A partial current density for CO of up to ca. 200 mA cm-2 was achieved at a cell voltage of ca. 3.3 V, in tandem with minimal H2 production. However, the analysis of cathodic and anodic outlet streams revealed that CO2 crossover across the AEM, mostly in the form of CO32- but partially as HCOO- generated over the cathode, actually exceeds the amount of CO2 converted to the target product, resulting in a poor utilization of the reactant and in the early onset of mass transfer limitations. In addition, CO2 crossover leads to non-stoichiometric decrease of the outlet flow rate from the cathodic compartment that can lead to a substantial overestimation of catalytic performance if the inlet flow rate of CO2 is used as reference for calculating partial current densities and Faradaic efficiencies. The results of this work highlight the importance of carrying out a carbon balance, in addition to traditional measurements of activity and selectivity, to adequately assess the performance of CO2 reduction devices at high current densities, and inform future efforts aimed at mitigating membrane crossover in MEA-type electrolyzers for CO2 reduction.

AB - Cell designs that integrate membrane-electrode assemblies (MEAs) with highly selective catalysts are a promising route to reduce ohmic losses and achieve high energy efficiency in CO2 reduction at industrially relevant current densities. In this work, porous silver filtration membranes are demonstrated as simple and efficient gas-diffusion electrodes for CO2 reduction to CO at high current densities in a MEA-type device. A partial current density for CO of up to ca. 200 mA cm-2 was achieved at a cell voltage of ca. 3.3 V, in tandem with minimal H2 production. However, the analysis of cathodic and anodic outlet streams revealed that CO2 crossover across the AEM, mostly in the form of CO32- but partially as HCOO- generated over the cathode, actually exceeds the amount of CO2 converted to the target product, resulting in a poor utilization of the reactant and in the early onset of mass transfer limitations. In addition, CO2 crossover leads to non-stoichiometric decrease of the outlet flow rate from the cathodic compartment that can lead to a substantial overestimation of catalytic performance if the inlet flow rate of CO2 is used as reference for calculating partial current densities and Faradaic efficiencies. The results of this work highlight the importance of carrying out a carbon balance, in addition to traditional measurements of activity and selectivity, to adequately assess the performance of CO2 reduction devices at high current densities, and inform future efforts aimed at mitigating membrane crossover in MEA-type electrolyzers for CO2 reduction.

KW - Electrocatalysis

KW - CO2 reduction

KW - Silver

KW - Anion-exchange membrane

KW - Membrane-electrolyde assembly

KW - Electrolyzer

U2 - 10.1021/acsami.9b13081

DO - 10.1021/acsami.9b13081

M3 - Journal article

VL - 11

SP - 41281

EP - 41288

JO - A C S Applied Materials and Interfaces

JF - A C S Applied Materials and Interfaces

SN - 1944-8244

IS - 44

ER -