Investigation of Redox Active Compounds for Use in Electrochemical Energy Devices

Author

Nathan Henry Mitchell, Louisiana State University and Agricultural and Mechanical CollegeFollow

Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Electrochemical energy devices such as redox flow batteries and CO₂ electrolyzers have the promise of being hugely beneficial in combating the extant anthropogenic CO₂ in our atmosphere and for dealing with our continual formation of anthropogenic CO₂. Redox flow batteries can help to ease the transition away from fossil fuels as an energy source, thereby minimizing future production of CO₂. CO₂ electrolyzers can not only remove CO₂ from the atmosphere but can transform the greenhouse gas into valuable feedstock chemicals. In the following work, we will examine an iron(III) porphyrin for use as a redox flow battery energy carrier and several electrocatalysts for CO₂ reduction.

Fe(III)TPP-Cl, which has long been used as an electrocatalyst for CO₂ reduction in NBu₄PF₆ in DMF. In this project, we aimed to determine if it could be used as an energy carrier in a nonaqueous redox flow battery system. Through this work, we were able to highlight an overlooked but important interaction that occurs between common tetralkylammonium support electrolytes and the most reduced form of Fe(III)TPP-Cl. We were then able to determine methods to bypass this unwanted reaction by charge/discharge cycling in KPF₆.

We then probed the effect of methylation of the bipyridine ring of Mn(bpy)(CO)₃Br to determine the ideal functionalization to facilitate immobilization on a working electrode. Throught this work, we were able to identify the methylation position which caused the least unwanted changes in the electrochemical properties of the parent complex.

In the final major project, we probed a combination of a molecular Iron(II) porphyrin immobilized alongside Copper nanoparticles on a carbon paper electrode for use in CO₂ electrolyzers. The effect of tandem electrocatalysis was examined in which the Iron(III) porphyrin produces CO at lower overpotentials and the CO is then shuttled to active copper sites where they can be further reduced to C₂₊products. In this work, we determined what effect the tandem electrocatalyst system has on electrocatalytic activity toward CO₂ reduction and production distribution.

Date

4-18-2025

Recommended Citation

Mitchell, Nathan Henry, "Investigation of Redox Active Compounds for Use in Electrochemical Energy Devices" (2025). LSU Doctoral Dissertations. 6742.
https://repository.lsu.edu/gradschool_dissertations/6742

Committee Chair

Elgrishi, Noémie