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Role of Ion-Selective Membranes in the Carbon Balance for CO2 Electroreduction via Gas Diffusion Electrode Reactor Designs

preprint
submitted on 29.04.2020 and posted on 30.04.2020 by Ming Ma, Sangkuk Kim, Ib Chorkendorff, Brian Seger

In this work, the effect of ion-selective membranes on the detailed carbon balance was systematically analyzed for high-rate CO2 reduction in flow electrolyzers. By using different ion-selective membranes, we show nearly identical catalytic selectivity for CO2 reduction, which is primarily due to a similar local reaction environment created at the cathode/electrolyte interface via the introduction of a catholyte layer. In addition, based on a systematic exploration of gases released from electrolytes and the dynamical change of electrolyte speciation, we demonstrate the explicit discrepancy in carbon balance paths for the captured CO2 at the cathode/catholyte interface via reaction with OH- when using different ion-selective membranes: (i) the captured CO2 could transport through an anion exchange membrane in the form of CO32-, subsequently releasing CO2 along with O2 in the anolyte, (ii) with a cation exchange membrane, the captured CO2 would be accumulated in the catholyte in the forms of CO32-, (iii) whereas under the operation of a BPM, the captured CO2 could be released at the catholyte/membrane interface in the form of gaseous CO2. The unique carbon balance path for each type of membrane is linked to ion species transported through membranes.

Funding

Villum Foundation V-SUSTAIN grant 9455 to the Villum Center for the Science of Sustainable Fuels and Chemicals

ECOEthylene project from the Innovation Fund Denmark (Grant# 8057-00018B)

SELECTCO2 project from Horizon 2020 of EU (Grant# 851441)

National Research Foundation of Korea (NRF-2019R1A2C2002156)

History

Email Address of Submitting Author

mingma@fysik.dtu.dk

Institution

Technical University of Denmark

Country

Denmark

ORCID For Submitting Author

0000-0003-3561-5710

Declaration of Conflict of Interest

There are no conflicts to declare.

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