Date of Graduation

9-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Chemical Engineering

Advisor/Mentor

Beitle, Robert

Committee Member

Cynthia Sides

Second Committee Member

Ed Clausen

Third Committee Member

Michael Ackerson

Fourth Committee Member

Tammy Lutz-Rechtin

Keywords

Bimetallic; Electrochemistry; Iron; Water treatment

Abstract

This dissertation explores the development, characterization, and application of iron-based catalysts for environmental remediation and energy generation. The research focuses on Fe-based nanomaterials for water purification, electrochemical ammonia production, and ethanol oxidation enhancement. The first section of the dissertation investigates the removal of water contaminants using nickel-iron (NiFe) bimetallic nanoparticles. Various NiFe ratios were synthesized and tested for their efficiency in degrading the azo dye (Orange G), with lower Ni content formulations achieving 80–99% dye removal within 60 minutes. Results show that changing the molar ratio of nickel to iron caused different removal rates, as well as the extent of overall elimination of azo dye from water. NiFe alloy nanoparticles were stabilized onto 5 different supports – two commercially available activated carbons and three custom synthesized heteropolyacid functionalized carbon. The carbons did not show an enhancement in dye removal until at the higher 100 gram starting concentration. Post-reaction characterization indicated the structurally disordered catalyst lost the metal at the surface oxidation occurred resulting in oxide and hydroxide presence for Fe and Ni to increase. The study was expanded to the degradation of energetic compounds, specifically TNT and RDX, using Fe(III)-embedded covalent organic frameworks (COFs). A mechanochemical synthesis approach allowed a 10× scale-up of COF production, improving yield efficiency from below 10% to 75%. Fluorescence-based detection enabled the sensitive quantification of TNT and RDX down to 1–4 µg/mL, while sequestration experiments demonstrated 90% TNT and 85% RDX removal within 30 minutes. Additional research focused on the application of Fe-COFs for nutrient and per- and polyfluoroalkyl substance (PFAS) removal. Adsorption studies demonstrated no selectivity for nitrate and phosphate, with Fe-functionalized supports underperforming conventional adsorbents. Electrochemical degradation pathways for PFAS were explored due to the slow adsorption rate for the COFs. The second section of this dissertation examines the role of Fe in electrocatalysis for sustainable energy applications. Ethanol oxidation reaction (EOR) behavior was tested using PtRhNi catalysts in Fe-doped electrolyte solutions. Fe incorporation was shown to increase current density by facilitating hydroxyl radical formation to cleave the C–C bond. This improvement resulted in more efficient ethanol oxidation with greater selectivity toward CO₂ production. Another avenue of research focused on electrochemical nitrogen reduction to ammonia (NRR) as a sustainable alternative to the Haber-Bosch process. However, rigorous control experiments revealed significant ammonia contamination, which compromised reported yields. Experiments were plagued with low production rates and faradaic efficiencies pointing to the need for improved catalyst selectivity. Further studies attempted to enhance NRR selectivity by functionalizing FeNi catalysts with thiol ligands, but results showed no effective binding, prompting a shift toward computational modeling and alternative ligand strategies. A comprehensive review of heterogeneous catalysts for NRR identified Fe-based catalysts with sulfur ligands as promising candidates for enhancing selectivity and reducing hydrogen evolution competition. Overall, this work advances the understanding of Fe-based catalysts for environmental and energy applications. The findings emphasize the need for further optimization in reaction kinetics, catalyst stability, and selectivity to enable large-scale deployment in water treatment and sustainable energy systems.

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