Doctor of Philosophy (PhD)
The extensive use of fossil fuels has increased the atmospheric concentration of CO2, resulting in global climate change. One way to mitigate the CO2 challenge is to convert it into useful chemicals electrocatalytically using renewable energies. Recent studies suggest that ligand-modified gold electrodes can enhance the Faradaic efficiency (FE) and selectivity of the electrochemical CO2 reduction reaction (CO2RR). This theoretical research, primarily based on density functional theory (DFT), has been carried out to understand the interactions of ligands with Au and possible effects on electrocatalytic activities. We systematically modeled and studied the adsorption of three different types of ligands, which bond through C, N, and S respectively, on Au surfaces in conjunction with various experimental techniques to clarify how the type of ligand, bonding site on Au surfaces, and many environmental factors such as electrode potential and aqueous solution influence the strength of the interaction. In addition, we theoretically investigated the enhancement of catalytic activity of Au electrode induced by the interaction between thiol ligands and Au electrode. We demonstrated that thiol ligands, such as 2-phenylethanethiol (2-PET) and 2-mercaptopropionic acid (2-MPA), modified Au electrodes by reconstructing the electrode surfaces to generate active Au defect sites, which promoted CO and hydrogen evolution reactions (HER). Our studies provide strong theoretical evidence for future research on the synthesis of novel ligand-Au catalysts.
Cheng, Xun, "First-Principle Study on the Interaction of Ligands with Gold and Effects on Catalytic Activities" (2020). LSU Doctoral Dissertations. 5139.