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Molina Villarino, Andres Abruna, Hector Hanrath, Tobias Muller, David 2024-04-05T18:47:22Z 2024-04-05T18:47:22Z 2023-08 ProQuest Submission ID: 13782 ProQuest Publication ID: 30569515 https://hdl.handle.net/1813/114709 https://doi.org/10.7298/x2fh-k154 16219248 231 pages Growing concerns regarding the energy crisis affecting the world and the environmental consequences of excess CO2 in the Earth’s atmosphere currently motivate a transition to renewable energy sources. However, energy storage and conversion devices are needed for renewables to challenge the uninterrupted, yet finite supply of energy obtained from burning fossil fuels, oil, natural gas, and coal. For the transportation sector, fuel cells and electrolyzers represent excellent alternatives to internal combustion engines and gasoline. Electrolyzers can use electricity from renewables such as wind or solar to split water into its elemental components and produce green hydrogen, which can be stored for future use. In turn, fuel cells can use this hydrogen to electrochemically generate electricity, which can power vehicles.While the water splitting and formation reactions represent an attractive cycle, the kinetics of the oxygen reduction and evolution reactions are quite sluggish. Therefore, any practical application of fuel cells and electrolyzers requires electrocatalysts. In acidic fuel cells, the most common commercial fuel cell used in cars, precious metal electrocatalysts such as Pt, Pt3Co, Pd and others are the standards. In contrast, in alkaline fuel cells non-noble metal electrocatalysts can be employed, making them especially attractive. In this work, I studied the electrochemical performance, stability, and practicality of some non-precious transition metal oxides as candidates for anion exchange membrane fuel cells. These included a series of La-based perovskite oxides and a specific Co-Mn spinel oxide. For characterizing these systems, I employed electrochemical techniques such as cyclic voltammetry and rotating disk electrode voltammetry, physical characterization techniques including thermogravimetric analysis, atomic emission spectroscopy, X-ray diffraction, scanning/transmission electron microscopy, X-ray photoelectron spectroscopy, and devices including fuel cell and electrolyzer membrane electrode assemblies. Contrary to popular opinion, none of the perovskite oxides were found to be sufficiently stable for practical applications as fuel cell electrocatalysts. However, the Co-Mn spinel oxide was confirmed as a promising candidate for practical applications, rivalling Pt in terms of mass activity and cost. Finally, the desire to test these materials for electrolyzer applications led us to design, build, and validate a prep and test station for anion exchange membrane electrolysis, which will open numerous possibilities for future research in our group, university, and research center. en Attribution-NoDerivatives 4.0 International https://creativecommons.org/licenses/by-nd/4.0/ electrocatalysts electrolyzers fuel cells manganese cobalt spinels nanoparticles oxides FIRST ROW TRANSITION METAL OXIDES AS ELECTROCATALYSTS FOR ANION EXCHANGE MEMBRANE FUEL CELLS AND ELECTROLYZERS dissertation or thesis https://newcatalog.library.cornell.edu/catalog/16219248 application/pdf Chemistry and Chemical Biology Cornell University Doctor of Philosophy Ph. D., Chemistry and Chemical Biology https://hdl.handle.net/1813/59810.2 Publication Cornell Theses and Dissertations Molina Villarino, Andres 5893a6ea-7af3-41d7-abc6-04bcd26ab5df open.access open.access <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="0eed2daa-fe72-44e9-8736-d87087a72d36"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>en</Language> <Title>FIRST ROW TRANSITION METAL OXIDES AS ELECTROCATALYSTS FOR ANION EXCHANGE MEMBRANE FUEL CELLS AND ELECTROLYZERS</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2023-08</PublicationDate> <DOI>https://doi.org/10.7298/x2fh-k154</DOI> <Authors> <Author> <DisplayName>Molina Villarino, Andres</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <OrgUnit /> </Publisher> </Publishers> <License>https://creativecommons.org/licenses/by-nd/4.0/</License> <Keyword>electrocatalysts</Keyword> <Keyword>electrolyzers</Keyword> <Keyword>fuel cells</Keyword> <Keyword>manganese cobalt spinels</Keyword> <Keyword>nanoparticles</Keyword> <Keyword>oxides</Keyword> <Abstract>Growing concerns regarding the energy crisis affecting the world and the environmental consequences of excess CO2 in the Earth’s atmosphere currently motivate a transition to renewable energy sources. However, energy storage and conversion devices are needed for renewables to challenge the uninterrupted, yet finite supply of energy obtained from burning fossil fuels, oil, natural gas, and coal. For the transportation sector, fuel cells and electrolyzers represent excellent alternatives to internal combustion engines and gasoline. Electrolyzers can use electricity from renewables such as wind or solar to split water into its elemental components and produce green hydrogen, which can be stored for future use. In turn, fuel cells can use this hydrogen to electrochemically generate electricity, which can power vehicles.While the water splitting and formation reactions represent an attractive cycle, the kinetics of the oxygen reduction and evolution reactions are quite sluggish. Therefore, any practical application of fuel cells and electrolyzers requires electrocatalysts. In acidic fuel cells, the most common commercial fuel cell used in cars, precious metal electrocatalysts such as Pt, Pt3Co, Pd and others are the standards. In contrast, in alkaline fuel cells non-noble metal electrocatalysts can be employed, making them especially attractive. In this work, I studied the electrochemical performance, stability, and practicality of some non-precious transition metal oxides as candidates for anion exchange membrane fuel cells. These included a series of La-based perovskite oxides and a specific Co-Mn spinel oxide. For characterizing these systems, I employed electrochemical techniques such as cyclic voltammetry and rotating disk electrode voltammetry, physical characterization techniques including thermogravimetric analysis, atomic emission spectroscopy, X-ray diffraction, scanning/transmission electron microscopy, X-ray photoelectron spectroscopy, and devices including fuel cell and electrolyzer membrane electrode assemblies. Contrary to popular opinion, none of the perovskite oxides were found to be sufficiently stable for practical applications as fuel cell electrocatalysts. However, the Co-Mn spinel oxide was confirmed as a promising candidate for practical applications, rivalling Pt in terms of mass activity and cost. Finally, the desire to test these materials for electrolyzer applications led us to design, build, and validate a prep and test station for anion exchange membrane electrolysis, which will open numerous possibilities for future research in our group, university, and research center.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>