Date Approved

4-19-2022

Embargo Period

4-20-2023

Document Type

Dissertation

Degree Name

Ph.D. Doctor of Philosophy

Department

Materials Science and Engineering

College

College of Science & Mathematics

Advisor

Samuel Lofland, Ph.D.

Committee Member 1

Jeffrey Hettinger, Ph.D.

Committee Member 2

Lei Yu, Ph.D.

Committee Member 3

Erik Hoy, Ph.D.

Subject(s)

Carbon dioxide; Electrochemicals industry

Disciplines

Materials Science and Engineering

Abstract

Electrochemical CO2 utilization is an attractive process for realizing carbon-neutral chemical production due to its electricity-driven ambient conditions, compatibility with renewable energy, and diversified products. This study aims to address unmet challenges hindering the wide adaptation of the process: (I) the absence of a highly selective and scalable catalyst for CO2 reduction reaction (CO2RR), (II) the large number of laborious experiments needed to optimize electrochemical materials/devices, and (III) the lack of an effective scheme for upgrading CO2-derived products. First, a bio-mimicking multi-component catalyst is explored, leading to the discovery of a highly selective Co-pyridine-derived catalyst for CO2RR into CO. The synergistic effect of Co and pyridine moieties successfully suppresses a side reaction, permitting the design of a membrane electrode assembly that can be scaled for industrial use. Second, a machine-learning-assisted procedure is introduced to accelerate material/device optimization. A judicious choice of design parameters combined with careful selection of the machine learning model based on the predicted target space minimizes the lab work required for enhanced performance. Third, the electrosynthesis of dimethyl carbonate (E-DMC) is studied as an upgrading catalytic reaction for CO. The feasibility of the synthesis is made possible by the discovery of a highly selective Pd-Au-derived catalyst that demonstrates synergistic modulation of the catalyst-intermediate interactions, and the rate of synthesis can be further boosted by adding a redox-mediator to the electrolyte. Lastly, these techniques for CO2RR and E-DMC can be successfully integrated into a single scheme for cost-effective CO2 utilization.

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