Author
Elrefaie, Ahmad
Other Contributors
Chakrapani, Vidhya; Shi, Sufei; Hedden, Ronald;
Date Issued
2020-12
Subject
Chemical engineering
Degree
MS;
Terms of Use
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute (RPI), Troy, NY. Copyright of original work retained by author.;
Abstract
An emphasis on the search for alternatives to fossil fuels which maintain energy storage capacities in performance similar to fossil fuels has driven research attempts at the development of batteries such as metal-air batteries, which require the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) to function. The focus of the thesis work was to determine if Mn2+ dissolution and redeposition during electrochemical polarization played an important role in catalytic OER and ORR processes on birnessite (δ-MnO2). It was our hypothesis that formation of Mn2+ occurred during negative (ORR) polarization. Given the high solubility and mobility of Mn2+, the as-formed Mn2+ will likely dissolve from δ-MnO2 electrode into the electrolyte. In contrast, positive polarization should result in the redeposition of dissolved Mn2+ back on the electrode surface, where the ions likely undergo oxidation to Mn3+. Therefore, we expected to see the concentration of Mn2+ in the electrolyte to show a potential-dependent trend. The results of our experiments agreed with the proposed hypothesis and showed an increase in the concentration of Mn2+ after the electrochemical charging of δ-MnO2 in 1 M KOH electrolyte at ORR potentials. This conclusion therefore provides insight and support to the possibility that Mn2+ acts as an active site during the catalysis of ORR on birnessite.;
Description
December 2020; School of Engineering
Department
Dept. of Chemical and Biological Engineering;
Publisher
Rensselaer Polytechnic Institute, Troy, NY
Relationships
Rensselaer Theses and Dissertations Online Collection;
Access
Restricted to current Rensselaer faculty, staff and students in accordance with the
Rensselaer Standard license. Access inquiries may be directed to the Rensselaer Libraries.;