Date of Award
5-1-2026
Document Type
Dissertation
Degree Name
Ph.D. in Chemistry
First Advisor
Jonah W. Jurss
Second Advisor
David A. Colby
Third Advisor
Saumen Chakraborty
School
University of Mississippi
Relational Format
dissertation/thesis
Abstract
Modern life depends on a steady and reliable supply of energy, yet meeting this demand sustainably remains one of the defining challenges of our time. While the Sun provides an immense and continuous source of energy, humanity has long relied on indirect forms of this energy stored in fossil fuels such as coal, oil, and natural gas. This dependence has come at a significant environmental cost. The large-scale combustion of fossil fuels releases vast amounts of carbon dioxide (CO2), a key greenhouse gas responsible for global warming, rising sea levels, and negative impacts on human health. Today, atmospheric CO2 levels have surpassed 422 ppm, far above pre-industrial levels of below 300 ppm, highlighting the urgency of addressing this issue. Renewable energy sources, including solar, wind, and hydroelectric power, offer cleaner alternatives, but their intermittent and diffuse nature limits their ability to fully replace fossil fuels. To bridge this gap, a promising approach is to use renewable energy to drive catalytic processes that transform abundant, low-value molecules into energy-rich fuels or valuable chemicals. Among these strategies, the catalytic reduction of CO2 stands out as particularly powerful, as it not only stores renewable energy in chemical form but also helps reduce atmospheric CO2 levels, moving us closer to a carbon-neutral energy cycle. Achieving this transformation requires the efficient transfer of both electrons and protons. This dissertation focuses on the development and mechanistic investigation of molecular catalysts for electrochemical and photochemical CO2 reduction to carbon monoxide and formate. Many known molecular CO2 reduction catalysts suffer from poor product selectivity, limited durability, and high overpotentials. To address these challenges, a dinuclear Ru complex was designed and synthesized using a rigid ligand framework with an extended ?-system 1,8-bis(2,2?:6?,2??-terpyridyl) anthracene (btpyan) in combination with 4,4'-tert-butyl bipyridine for increasing the rigidity of the catalyst system to compare with mononuclear Ru complexes, inspired by our previous study on a dinuclear rhenium complex (Chapter 2). In a bimetallic catalyst system, the two metals can work together synergistically to promote C–O bond cleavage and significantly boost selectivity. In a subsequent study, our work focused on the development of a Ni-based molecular catalyst bearing a redox-active pentadentate ligand with secondary amine groups in the outer coordination sphere for catalytic CO2 reduction. Building on this work, one additional collaborative project centers on designing and developing first-row transition metal complexes (Ni and Co) paired with macrocyclic ligand frameworks functionalized with intramolecular hydrogen-bond donors in the secondary coordination sphere for CO2 reduction. Macrocyclic ligands are highly effective in stabilizing metal centers and, providing the coordination environment necessary to facilitate multi-electron transfer reactions. They also stabilize intermediates during the catalytic cycle through the synergistic effects of metal–ligand interactions.
Recommended Citation
Ferdous, Jannatul, "Molecular Design, Development, and Mechanistic Evaluation of Advanced Transition-Metal Catalysts for CO2 Reduction" (2026). Electronic Theses and Dissertations. 8816.
https://egrove.olemiss.edu/etd/8816