FIRST ROW TRANSITION METAL OXIDES AS ELECTROCATALYSTS FOR ANION EXCHANGE MEMBRANE FUEL CELLS AND ELECTROLYZERS

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.

Name thesis:degree_name

Ph. D., Chemistry and Chemical Biology

Level thesis:degree_level

Doctor of Philosophy

Discipline thesis:degree_discipline

Chemistry and Chemical Biology

Grantor

Cornell University

Year dc:date.issued

2023

Author dc:creator

• Molina Villarino, Andres

Committee members dc:contributor.committeemember

• Hanrath, Tobias
• Muller, David

• electrocatalysts
• electrolyzers
• fuel cells
• manganese cobalt spinels
• nanoparticles
• oxides

Statement dc:rights

• Attribution-NoDerivatives 4.0 International

Licence dc:rights.uri

• https://creativecommons.org/licenses/by-nd/4.0/

Language dc:language.iso

en

DOI

https://doi.org/10.7298/x2fh-k154

Dc Identifier Other

ProQuest Submission ID: 13782
ProQuest Publication ID: 30569515

OAI identifier oai:identifier

oai:ecommons.cornell.edu:1813/114709