Date of Award
12-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemical and Biomolecular Engineering
Abstract
The excessive release of carbon dioxide (CO2) into the atmosphere has become a major cause of global warming and ocean acidification, threatening the sustainability of human life on Earth. To address this challenge, scientists are exploring ways to convert CO2 into useful fuels and chemicals instead of simply capturing and storing it. One promising approach is electrocatalysis, which uses electricity—potentially from renewable sources—to drive chemical reactions that transform CO2 under mild, environmentally friendly conditions.
This research aims to understand how the arrangement of atoms in metallic catalysts affects the conversion of CO2 and carbon monoxide (CO) into valuable products such as methane, ethylene, ethanol, and acetate. Copper (Cu) is a unique catalyst because it can form a wide range of multi-carbon products, but it often produces many at once, making the process inefficient. To overcome this limitation, this study explores the effect of adding very small amounts of another metal, palladium (Pd), to copper. By precisely controlling how palladium atoms are placed on the copper surface—either as isolated single atoms or small clusters—the study investigates how these atomic structures influence the reaction’s efficiency and product selectivity.
The catalysts were prepared using a simple process called galvanic displacement, which allows single palladium atoms to replace copper atoms on the surface in a highly controlled way. These single-atom alloys exhibited unexpected behavior: instead of promoting unwanted hydrogen formation, as palladium typically does, the atomically dispersed palladium helped strengthen the bonding of carbon-containing intermediates, iii thereby enhancing CO2 conversion activity. The natural surface shapes of copper were also found to matter—different atomic arrangements favored the formation of different products. For example, certain surfaces promoted methane production, while others favored ethylene.
Further experiments showed that the number and spacing of palladium atoms on copper—known as site density—had a strong effect on which products formed. When the palladium atoms were far apart, the catalyst mainly produced ethylene. When they were closer together, it shifted to making ethanol. When two palladium atoms bonded as pairs (dimers), a new product, acetate, became dominant. This reveals that not only the type of metal but also the precise atomic arrangement and spacing can determine which chemical pathways occur.
Overall, this study shows that by controlling catalysts at the atomic level— adjusting the dispersion, density, and atomic pairing of metal atoms—it is possible to direct chemical reactions toward specific outcomes. These findings provide new insights into how atomic structure shapes catalytic performance and open new directions for designing efficient, selective, and sustainable materials that can help recycle CO2 into useful products, contributing to a cleaner and more sustainable energy future.
Recommended Citation
Jin, Zehua, "Atomic-Scale Engineering of Dilute Pd–Cu Alloys for Selective Electrocatalytic Cox Reduction" (2025). All Dissertations. 4195.
https://open.clemson.edu/all_dissertations/4195
Author ORCID Identifier
0000-0002-5619-337X