(3hb) Promoting New Chemical Routes by Materials Design

From inorganic substances to organic compounds and their derivatives, economies hinge on chemical production. Recently emerging fields such as artificial intelligence sectors require active chemicals that are key to the performance of energy storage systems, and furthermore, traditional target markets of chemical industries including consumer products, fuels, and agriculture continuously grow. Currently operating processes for valuable chemical products are adjusted to specific feedstocks (e.g., crude oil), of which the supply is subject to geopolitical situations and fluctuations in the global economy. Allowing the use of alternative feedstock or new processes of obtaining raw materials can address these economic challenges, and incorporating diverse feeds into practical chemical production requires the development of fundamentally new materials that can accommodate distinct properties of chemicals involved in the processes.

Enabling discoveries in catalytic material development needs deep understanding of key physicochemical properties that govern reactivity and the ability to establish reasonable approaches to synthesize and characterize the target materials. With this regard, my research has focused on (i) rationally designed synthesis of organic and inorganic materials with tailored properties for adsorption, catalysis, and redox reactions and (ii) development of characterization methods for structural properties that are critical to the activity. Some of those approaches from my prior research are described in the following:

Development of thermally stable chiral molecular sieves for enantiomeric separation [1] Computationally designed enantiopure organic structure-directing agents enables the crystallization of STW-type chiral molecular sieve with a high-silica framework composition, which exhibits thermal stability at 800 ^oC. This material showcases a more realistic zeotype-based enantiomeric separation with thermal regenerations.

Synthetic control of site-specific incorporation of catalytic active sites and probing their local geometry by NMR spectroscopy [2-3] A series of synthesis-characterization work on borosilicate molecular sieves reveal that local geometry surrounding the active site (framework-incorporated boron) can be estimated by ¹¹B NMR chemical shift. This result helps interpret the result of a related study: carefully designed two isomorphic organic cations with distinct location of positive charges show different interactions with framework boron species, leading to the alteration of preferred location of active sites by charge interaction during the hydrothermal treatment.

Elucidation of irreversible, degradative phase transition of Ni-doped LiCoO₂ via voltage-driven entropy measurement [4] LiCoO₂ cathode degrades over electrochemical cycles by the loss of its crystal structure and substituting Ni for Li mitigates the structural deformation. This work demonstrates the effect of Ni doping in the context of (i) entropy measurement of crystalline Ni-doped LiCoO₂ by temperature dependence of open circuit voltage and (ii) the detection of degradative phase transition by entropy change profile, which can lead to real-time diagnoses of electrode materials without cell disassembly.

Taken together, I have developed tools necessary to discover structure-activity relationships across an array of active materials.

My research moving forward will be to approach practical challenges for new chemical routes through synthesis and characterization pathways to create catalytic materials with properties tuned for specific chemical processes. A primary portion of my research efforts will be revealing the foundation of activity via tailored characterization techniques to help enable the creation of materials with desired catalytic properties. For instance, the design of bi-phasic catalysts with separately localized hydrophobic and hydrophilic regions could provide a way to diminish the effect water present in feed, enabling the conversion of nonconventional feedstock such as byproducts or wastes of chemical and biological processes. Strategies to create such materials involve localizing the active site within hydrophobic boundary of catalyst by introducing nonpolar moieties connected to the elements of active site. Another avenue to these approaches can be to optimize the microenvironments around active sites within nanoporous materials. With careful consideration of the active site metal species and pore geometry, the population of hydrophilic defects and their vicinity to active centers can be tuned to alter the local solvation environment around the active sites, leading to desired catalytic activities. My research group will continue to tackle problems in the development of materials and corresponding chemical cycles by creating new synthesis routes and characterization protocols.

Teaching Interests:

Creating enjoyable learning environments and teaching students is one of the main reasons I am interested in pursuing a career in academia. I can teach any introductory chemical engineering courses, and I am most excited and qualified to teach thermodynamics, kinetics, catalysis, and spectroscopy courses at both undergraduate and graduate levels. Furthermore, I am interested in creating new courses centered on chemical engineering combined with material structures. The purpose of these courses will be to provide students with an integrated perspective of kinetics, thermodynamics, and transport with a focus on the synthesis and properties of solid-state materials. The class will cover a combination of examples of active materials and their practical applications, the thermodynamic and kinetic principles governing their synthesis, and the transport phenomena such as molecular diffusion or particle motions within/around these materials and their consequences on the chemical reactions occurring on the solid-state materials. This will offer in-class exposure to a broad range of problems where core concepts of chemical engineering play together and benefit students interested in materials research in a variety of fields of chemical engineering.

References

[1] Park, Y., Alshafei, F.H., Hernandez-Rodriguez, I., Silva De Moraes, L., Deem, M.W., Nelson, H., and Davis, M.E. “High-silica, enantiomerically enriched STW-type molecular sieves.” Chem. Mater. 2024, 36 (21), 10552-10559.

[2] Park, Y., Koller, H., Lew, C.M., Zones, S.I., and Davis, M.E. “Correlating local geometry to ¹¹B NMR chemical shifts of tetrahedrally coordinated boron in molecular sieves.” J. Phys. Chem. C 2024, 128 (25), 10705-10713.

[3] Park, Y., Samkian, A. E., Sercel, Z. P., Cusumano, A. Q., Gonzales, K. J., Koller, H., Zones, S. I., Stoltz, B. M., and Davis, M.E. "Controlled heteroatom incorporation at specific framework sites within molecular sieves." In preparation.

[4] Kim, H.J.,^† Park, Y.,^† Kwon, Y., Shin, J., Kim, Y.-H., Ahn, H.-S., Yazami, R., and Choi, J.W. “Entropymetry for non-destructive structural analysis of LiCoO₂ cathodes.” Energy Environ. Sci., 2020, 13 (1), 286-296. ^†indicates co-first authorship.