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Conducting Polymer Electrodes for Oxygen Reduction Reaction
Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Both the pollution level of the environment and the increasing energy demands have stimulated intense research on the development of low-cost environmentally-friendly energy conversion and storage systems with high efficiency, such as metal-air batteries and fuel cells.

One of the most essential parts of both fuel cells and metal–air batteries is the air-electrode which is responsible for the reduction of O2. The air-electrode can use O2 from air facilitating the layout of the device; however, the process taking place on it is significantly complex. Currently, platinum (Pt) is the benchmark for air-electrodes in such technologies, although it is expensive and exhibits other important disadvantages which diminish the fuel cell performance. Therefore, extensive research has been devoted to reduce the amount of Pt used in air-electrodes and to develop a noble metal-free version of these electrodes.

The area of printed electronics could facilitate the development of low-cost electrodes produced in high volume for such applications. Conducting polymers are attractive materials for this technology because they may combine several desired properties, like electronic conduction, ionic conduction and catalysis of electrochemical reactions.

Among other conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) emerged as an alternative cathode catalyst material to Pt, due to its ability to effectively catalyze the oxygen reduction reaction (ORR), while it also exhibits high electrical and ionic conductivity.

The focus of this thesis is to study the electrocatalytic activity and mechanism of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) when employed as an airelectrode in energy storage devices, such as fuel cells and metal-air batteries. Although PEDOT is extensively studied during the last decade as an air-electrode for fuel cell and metal-air batteries, vital pieces of the catalytic mechanism that PEDOT follows remain unknown, namely: (i) the sites of PEDOT on which O2 interacts and (ii) the intermediate species which are formed during the ORR. The content of this thesis tackles these topics, both from experimental and theoretical point of view. Moreover, it investigates the use of PEDOT as an active electrocatalyst in a polymer exchange membrane (PEM) fuel cell, by embedding the polymer in a cellulose matrix, aiming to fabricate a gas diffusion electrode for the ORR side of the device. Finally, the goal of the thesis surpasses the limit of the p-doped PEDOT and undertakes the evaluation of a n-type conjugated polymer of high electron affinity as a cathode in reduction processes.  

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2018. , p. 103
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1915
National Category
Other Chemical Engineering
Identifiers
URN: urn:nbn:se:liu:diva-147720ISBN: 9789176853450 (print)OAI: oai:DiVA.org:liu-147720DiVA, id: diva2:1204290
Public defence
2018-06-01, K3, Kåkenhus, Campus Norrköping, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2018-05-07Bibliographically approved
List of papers
1. Solution processed liquid metal-conducting polymer hybrid thin films as electrochemical pH-threshold indicators
Open this publication in new window or tab >>Solution processed liquid metal-conducting polymer hybrid thin films as electrochemical pH-threshold indicators
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2015 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 29, p. 7604-7611Article in journal (Refereed) Published
Abstract [en]

A global and accurate mapping of the environment could be achieved if sensors and indicators are mass-produced at low cost. Printed electronics using polymeric (semi) conductors offer a platform for such sensor/indicator based circuits. Herein, we present the material concept for an electrochemical pH-threshold indicator based on a printable hybrid electrode which comprises a liquid metal alloy (GaInSn) embedded in a conducting polymer matrix (PEDOT). This hybrid electrode displays a large variation in open circuit potential versus pH in an electrochemical cell, which when connected to the gate of an electrochemical transistor leads to a dramatic change in the drain current in a narrow range of pH.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2015
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-120667 (URN)10.1039/c5tc00753d (DOI)000358228400010 ()
Note

Funding Agencies|European Research Council (ERC-starting-grant) [307596]; European Commission; Region Wallonne (FEDER Revetements Fonctionnels program) [475225-579695]; BELSPO [IAP 7/05]; OPTI2MAT Excellence program of Region Wallonne [816925]; FNRS-FRFC

Available from: 2015-08-20 Created: 2015-08-20 Last updated: 2018-08-20
2. Oxygen-induced doping on reduced PEDOT
Open this publication in new window or tab >>Oxygen-induced doping on reduced PEDOT
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2017 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 9, p. 4404-4412Article in journal (Refereed) Published
Abstract [en]

The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) has shown promise as air electrode in renewable energy technologies like metal-air batteries and fuel cells. PEDOT is based on atomic elements of high abundance and is synthesized at low temperature from solution. The mechanism of oxygen reduction reaction (ORR) over chemically polymerized PEDOT: Cl still remains controversial with eventual role of transition metal impurities. However, regardless of the mechanistic route, we here demonstrate yet another key active role of PEDOT in the ORR mechanism. Our study demonstrates the decoupling of conductivity (intrinsic property) from electrocatalysis (as an extrinsic phenomenon) yielding the evidence of doping of the polymer by oxygen during ORR. Hence, the PEDOT electrode is electrochemically reduced (undoped) in the voltage range of ORR regime, but O-2 keeps it conducting; ensuring PEDOT to act as an electrode for the ORR. The interaction of oxygen with the polymer electrode is investigated with a battery of spectroscopic techniques.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-136229 (URN)10.1039/c6ta10521a (DOI)000395926100019 ()
Note

Funding Agencies|European Research Council (ERC) [307596]; Knut and Alice Wallenberg foundation; Wenner-Gren Foundations; Swedish Research Council; Swedish Foundation for Strategic Research [0-3D]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]

Available from: 2017-03-31 Created: 2017-03-31 Last updated: 2018-05-07

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