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Revealing Mechanistic Processes in Gas-Diffusion Electrodes During CO2 Reduction via Impedance Spectroscopy

Bienen, Fabian and Kopljar, Dennis and Löwe, Armin and Geiger, Simon and Wagner, Norbert and Klemm, Elias and Friedrich, Kaspar Andreas (2020) Revealing Mechanistic Processes in Gas-Diffusion Electrodes During CO2 Reduction via Impedance Spectroscopy. ACS Sustainable Chemistry and Engineering, 8 (36), pp. 13759-13768. American Chemical society (ACS). DOI: 10.1021/acssuschemeng.0c04451 ISSN 2168-0485

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Official URL: http://dx.doi.org/10.1021/acssuschemeng.0c04451


The use of gas-diffusion electrodes (GDEs) as CO2 converting electrodes increases the achieved current densities for the CO2 reduction reaction (CO2RR) by a multiple (>100 mA cm−2) compared to planar electrodes (10 mA cm−2), whereas the long-time stability of the employed GDEs is a crucial factor for the industrial realization of this technology. We investigated carbon-supported tin-based GDEs by electrochemical impedance spectroscopy with the goal to identify the underlying physical processes by varying the applied current density, temperature, CO2 partial pressure, and electrolyte, an unexplored task so far. The spectrum displays four features which we interpreted as (i) ionic and electronic conductivity in the porous system, (ii) reaction of CO2 with OH− to form bicarbonate, (iii) charge transfer converting CO2 (aq) to CO2 •−, and (iv) liquid phase diffusion of CO2 (aq). Besides the assignment of the physical processes to the features obtained in the spectrum, we conclude that the observed spectrum shape is affected by CO2RR and hydrogen evolution reaction, whereby the shape dominating reaction switches with varying experimental conditions such as temperature, CO2 volume fraction, current density, and electrolyte.

Item URL in elib:https://elib.dlr.de/136695/
Document Type:Article
Title:Revealing Mechanistic Processes in Gas-Diffusion Electrodes During CO2 Reduction via Impedance Spectroscopy
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Bienen, FabianFabian.Bienen (at) dlr.dehttps://orcid.org/0000-0002-4660-8826
Kopljar, DennisDennis.Kopljar (at) dlr.dehttps://orcid.org/0000-0002-2228-2016
Löwe, Arminarmin.loewe (at) itc.uni-stuttgart.dehttps://orcid.org/0000-0001-5149-781X
Geiger, Simonsimon.geiger (at) dlr.dehttps://orcid.org/0000-0002-2968-5029
Wagner, NorbertNorbert.Wagner (at) dlr.dehttps://orcid.org/0000-0002-2596-8689
Friedrich, Kaspar AndreasAndreas.Friedrich (at) dlr.dehttps://orcid.org/0000-0002-2968-5029
Date:20 August 2020
Journal or Publication Title:ACS Sustainable Chemistry and Engineering
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1021/acssuschemeng.0c04451
Page Range:pp. 13759-13768
Publisher:American Chemical society (ACS)
Keywords:CO2 electrolysis, CO2RR, electrochemical impedance spectroscopy, tin, gas-diffusion electrode, GDE, CO2
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Electrolysis and Hydrogen
DLR - Research area:Energy
DLR - Program:E SP - Energy Storage
DLR - Research theme (Project):E - Elektrochemical Processes (Electrolysis)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Bienen, Fabian
Deposited On:23 Oct 2020 11:34
Last Modified:23 Oct 2020 11:34

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