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La0.1Ca0.9MnO3/Co3O4 for oxygen reduction and evolution reactions (ORER) in alkaline electrolyte
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.ORCID iD: 0000-0002-4671-205x
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.ORCID iD: 0000-0002-6212-4194
2018 (English)In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, p. 1-14Article in journal, Editorial material (Refereed) Published
Abstract [en]

Non-precious metal bifunctional catalysts are of great interest for metal–air batteries, electrolysis, and regenerative fuel cell systems due to their performance and cost benefits compared to the Pt group metals (PGM). In this work, metal oxides of La0.1Ca0.9MnO3 and nano Co3O47 catalyst as bifunctional catalysts were used in oxygen reduction and evolution reactions (ORER). The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption isotherms. The electrocatalytic activity of the perovskite-type La0.1Ca0.9MnO3 and Co3O4 catalysts both as single and mixtures of both were assessed in alkaline solutions at room temperature. Electrocatalyst activity, stability, and electrode kinetics were studied using cyclic voltammetry (CV) and rotating disk electrode (RDE). This study shows that the bifunctional performance of the mixed La0.1Ca0.9MnO3 and nano Co3O4 was superior in comparison to either La0.1Ca0.9MnO3 or nano Co3O4 alone for ORER. The improved activity is due to the synergistic effect between the La0.1Ca0.9MnO3 and nano Co3O4 structural and surface properties. This work illustrates that hybridization between these two metal oxides results in the excellent bifunctional oxygen redox activity, stability, and cyclability, leading to a cost-effective application in energy conversion and storage, albeit to the cost of higher catalyst loadings.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2018. p. 1-14
National Category
Chemical Engineering
Research subject
Chemical Engineering; Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-222516DOI: 10.1007/s10008-017-3862-2ISI: 000431668000007Scopus ID: 2-s2.0-85040363046OAI: oai:DiVA.org:kth-222516DiVA, id: diva2:1181937
Funder
Swedish Energy Agency, 39078-01
Note

QC 20180212

Available from: 2018-02-12 Created: 2018-02-12 Last updated: 2019-01-24Bibliographically approved
In thesis
1. Studies on Rechargeable Fe-air electrodes in Alkaline electrolyte
Open this publication in new window or tab >>Studies on Rechargeable Fe-air electrodes in Alkaline electrolyte
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Energy storage system is an important component in the energy system based on variable renewable energy sources into the grid. Energy storage system could contribute to decarbonization, energy security, offset the demand and supply of the electricity sector, especially for the electric grid. These can be either mechanical, electrochemical, chemical, electromagnetic or thermal devices. The most important functional characteristics of an energy storage system are capital cost, roundtrip efficiency, energy and power rating, response times and cycle life. Electrochemical energy storage systems (EES) have the following edge over the other systems: fast response time, relatively short duration of storage, size, high efficiency, a decentralized installation which is closer to generation or consumption site.

The focus of this thesis is on the development of cost-effective iron anode materials and electrocatalytic air electrodes for Fe-air batteries that potentially could become as an energy storage system. Iron-based systems are attractive due to their safety, cheapness, non-toxicity and ubiquitous availability of materials. However, both the anode and cathode parts have numerous drawbacks that need to be addressed. The anode exhibits poor charge efficiency, rate capability and low capacity utilization while the cathode has sluggish kinetics, poor activity, structural stability and the numbers of active non-noble metal catalysts are limited.

This work utilized Cu and Sn-doped iron nanomaterials and different additives (Bi2S3, CNT, LiOH) to enhance the performance of the iron electrode. The performance of the electrodes were evaluated using the charge/discharge cycling, rate capability, cyclic voltammetry (CV), galvanostatic and potentiodynamic polarization measurements, in operando charging measurements combined with mass spectrometry. The fresh and cycled electrodes and powders were characterized by ex-situ XRD, BET, SEM, TEM , XPS and Raman spectroscopy. The most striking results are the prevention of nanoparticle agglomeration, increased charging efficiency (80-91%), effect of Cu and Sn dopants on specific capacity (367-603 mAh g-1) and improved performance of the electrodes at high charge current densities.

In the subsequent air electrode part, non-precious metal La-doped CaMnOx, nano Co3O4 and NiFeOX electrocatalysts were synthesized using co-precipitation and hydrothermal methods. Both the single and mixed catalysts were used as bi-functional catalysts for oxygen reduction and evolution reactions (ORER). The catalysts were characterized by XRD, SEM, TEM, BET, Raman and XPS. The electrocatalytic activity and stability were assessed in alkaline solutions on gas diffusion electrodes and glassy carbon electrode by linear sweep voltammetry (LSV), CV and rotating disk electrode (RDE). Furthermore, the mixed catalyst and NiFeOX showed excellent bifunctional performance such as high activity and stability achieved by the hybridization of the two catalysts and the effect of catalyst loading on the electrocatalytic performance. These findings can help to develop a cost-effective material for Fe-air batteries.

Place, publisher, year, edition, pages
Stockholm: KTH, 2019. p. 108
Keywords
Fe-air battery; Cu/Sn-doped nanostructured iron electrodes, Alkaline electrolytes, Bi-functional OER/ORR catalyst, perovskite/spinel catalyst, NiFeOx, air electrode
National Category
Engineering and Technology Chemical Process Engineering Chemical Sciences
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-241534 (URN)978-91-7873-087-2 (ISBN)
Public defence
2019-03-01, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency, 39078-1
Note

QC 20190124

Available from: 2019-01-24 Created: 2019-01-23 Last updated: 2019-02-22Bibliographically approved

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Paulraj, Alagar R.Kiros, Yohannes

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