Doctor of Philosophy (PhD)
Electrochemical CO2 reduction (ECO2RR) has emerged as a promising approach for generating carbon-neutral liquid fuels by utilizing excess renewable electricity to convert CO2. This thesis aims to employ atomistic simulations by using Density Functional Theory (DFT) to investigate the mechanistic details of how transition metal sulfides and electro-organocatalysts can enhance the activity and selectivity towards desired products, including those containing C-H bonds and molecules with C-C bonds. For this project, three different electrocatalysts were designed computationally.
Firstly, MoS2 was chosen as a transition metal sulfide catalyst with the objective of understanding the kinetics involved in the reduction of CO2 to CO at a low overpotential of -0.5 V vs. RHE and pH of 4. The aim was to identify the rate-limiting step with an energy barrier as low as 0.74 eV. Secondly, 1,3-dimethyl-4-imidazoline electro-organocatalyst was utilized to explore CO2 reduction beyond CO production. Under specific conditions of pH 7.85, an electrode potential of -0.85 V vs. RHE, and a temperature of 80 ℃, this organomolecule demonstrated the capability of reducing CO2 to formaldehyde. The reaction proceeded through a series of steps, including CO2 activation, Proton-Coupled Electron Transfer (PCET), Tautomerization, dehydration, and elimination, ultimately resulting in the formation of products with C-H bonds.
The same electro-organocatalyst, 1,3-dimethyl-4-imidazoline, was investigated for its potential to form long-chain aldehydes through reductive aldol condensation. This process involved the incremental growth of an alkyl chain by one carbon atom at a time. By performing reductive addition of formaldehyde to a second aldehyde, an extended product aldehyde was generated. Under specific conditions of an electrode potential of -0.88 V vs. RHE, a formaldehyde
concentration of 8.71×10-3 mol/L (log[CH2O]=-2.06), and a pH of 6.63, this molecule successfully reduced CO2 to acetaldehyde.
Khezeli, Foroogh, "Computational Design of Electro-Organocatalysts and Transition Metal Sulfides for the Electrochemical Reduction of CO2" (2023). LSU Doctoral Dissertations. 6240.
Available for download on Friday, July 10, 2026