Jinwon Cho

(Advisor: Prof. Seung Soon Jang)

will defend a doctoral thesis entitled

Development of Novel Platforms for Homogeneous and Heterogeneous Catalysis Toward Sustainable Chemistry:

A Multiscale Modeling Approach

on

Wednesday, April 17 at 9:30 a.m.

MRDC 3515

and

Virtually via Zoom

Abstract

Catalysis is used in a wide range of applications, including those involved in producing drugs, bioproducts, and chemical hydrogen storage. The key challenge in catalyst design is achieving high reaction rate, selectivity, and durability across various branches of chemistry. Recent advances in computational chemistry have significantly contributed to the design of the next generation of catalysis by rationalizing experimental observations, elucidating reaction mechanisms, and identifying key descriptors. In this proposal, a multiscale modeling approach was employed to address challenges in both homogenous catalysis for aldol addition reaction and heterogenous catalysis for electrochemical CO2 reduction to formic acid, aiming for sustainable and green chemistry.   

In the first part of research, we have proposed the self-assembled multicompartment micelles (MCMs), which is formed spontaneously by amphiphilic block copolymers in water solvent, as a nanoreactor for the proline catalyzed aldol addition reaction. Despite the longstanding existence of the asymmetric aldol addition reaction, it continues to present challenges in achieving high yields and selectivity in water medium, which is considered as the most environmentally friendly solvent. In this regard, MCMs is used as a support system that encapsulates catalysis in the hydrophobic core, making them suitable for the desired reactions within an aqueous medium. This approach allows the effective confinement and protection of catalytic species within the MCMs, leading to enhanced catalytic performance and selectivity. To design these MCMs, we developed a multiscale computational protocol for calculating the Flory-Huggins 𝜒-parameter, pivotal in predicting the miscibility of polymer-polymer and polymer-solvent blends. This 𝜒-parameter is employed to predict the morphology of MCMs, which is influenced by block ratio, sequence, and the location of catalytic sites within the polymer chain. Finally, the aldol addition reaction between acetone and 4-nitrobenzaldehyde was assessed via density functional theory within the MCM environment, in comparison to various organic solvents.

The second part of the research, using density functional theory, we have focused on the design of novel heterogeneous catalyst that promotes electrochemical CO2 reduction to formic acid. Such highly active and stable electrocatalysts can be obtained by modifying chemical and physical properties of metal surfaces via a deposition of transition metal monolayer on graphene. The hybridization of sp and d orbitals between graphene and metal, which significantly reduces the local density of states of d-band of metals and increased s-and p-orbital of graphene near the Fermi level, leads to a strong covalent bonding between late transition metal monolayer and graphene (M/G). In addition, we discovered that the charge polarization on graphene in M/G induces a deposition of another thin metallic film on the graphene, thus forming M/G/M structures. We evaluated the overpotential required for CO2 reduction to formic acid has been calculated on M/G and M/G/M structures to assess true catalytic activity as well as hydrogen evolution reaction and CO2 reduction to carbon monoxide for the selectivity evaluation. Finally, the effect of local electric field, generated by cations in the electrolyte and the negative charged electrode, was investigated on the CO2RR kinetics. 

Committee

• Prof. Christopher W. Jones – School of Chemical and Biomolecular Engineering
• Prof. Natalie Stingelin– School of Materials Science and Engineering
• Prof. Faisal M. Alamgir – School of Materials Science and Engineering
• Prof. Marcus Weck – Department of Chemistry, New York University