Computational Materials Design for Catalysis and Energy Materials

During the past decade the theoretical description of science and engineering phenomena has undergone a dramatic development. Today’s advances in computational capabilities and algorithms make it possible to design new materials with properties tailored to specific applications within the detail and accuracy required for computational results to compare with experiments. We have guided experimental efforts, using the information of new materials at the atomic and molecular level obtained by the state-of-the-art theoretical methods such as density functional theory (DFT) calculations. Our focus here is on the discovery of materials with desired properties for a wide range of important applications in catalysts and energy materials. Specific examples include as follows;

(1) Synthesis and separation of enantiopure chemicals is of enormous importance in the pharmaceutical industry. We studied several classes of solid surfaces that are chiral to aid the development of new materials for applications in chiral chemical processing. These materials include chiral minerals such as quartz, highly stepped metal surfaces that are intrinsically chiral, and atomically flat metals that are decorated with chrial molecules such as amino acids.

(2) Transition metal carbides have received considerable attention as promising catalysts due to their electronic and catalytic properties similar to the noble metals, but with more resistance to sulfur poisons. Alkali promoters are known to enhance the efficiency of the catalytic activity of these materials, but the detailed mechanisms remain elusive. We examined how alkali promoters bind on these surfaces, providing a useful foundation for the catalytic selectivity in the chemical reactions such as Fischer-Tropsch synthesis.

(3) Solid oxide fuel cells (SOFCs) have been attractive given its fuel flexibility and high conversion efficiencies. The slow rate of oxygen reduction at the cathode is, however, the main barrier to achieve higher power output in SOFCs at intermediate temperatures. Recently, lattice strain was shown to have a significant impact on facilitating oxygen ion transport, vacancy formation, and surface reactions for SOFC-related materials. We mechanistically investigated strain effects on the surface chemistry, electronic structure, and oxygen incorporation, showing how the lattice strain should be controlled to attain fast oxygen reduction kinetics on the cathode materials.

Our computational modeling has elucidated fundamental understanding of the correlation between materials structure and properties. Theoretical guidance based on this can play a valuable role on novel chemical processes and important technological advances by directing experimental efforts to the most promising of many possible materials that can be considered.

Postdoctoral Advisor: Professor Bilge Yildiz, Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA

Doctoral Thesis Advisor: Professor David S. Sholl, School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA

Publications:

1. Jeong Woo Han and Bilge Yildiz, Enhanced one dimensional mobility of oxygen on strained LaCoO₃ (001) surface, J. Mater. Chem. Advance Article (2011) DOI:10.1039/C1JM12830B.
2. Zhuhua Cai, Yener Kuru, Jeong Woo Han, Yan Chen, and Bilge Yildiz, Surface Electronic Structure Transitions at High Temperature on Perovskite Oxides: The Case of Strained La_0.8Sr_0.2CoO₃ Thin Films, J. Am. Chem. Soc. ACS Just Accepted (2011).
3. Jeong Woo Han, Joanna N. James, and David S. Sholl, Chemical speciation of adsorbed glycine on metal surfaces, J. Chem. Phys. 135 (2011) 032127.
4. Helia Jalili†, Jeong Woo Han†, Yener Kuru, Zhuhua Cai, and Bilge Yildiz, New Insights into the Strain Coupling to Surface Chemistry, Electronic Structure, and Reactivity of La_0.7Sr_0.3MnO₃, J. Phys. Chem. Lett. 2 (2011) 801-807. †Equally contributed
5. Jeong Woo Han, Liwei Li, and David S. Sholl, Density Functional Theory Study of H and CO Adsorption on Alkali-Promoted Mo₂C Surfaces, J. Phys. Chem. C 115 (2011) 6870-6876.
6. Jeong Woo Han, Helia Jalili, Yener Kuru, Zhuhua Cai, and Bilge Yildiz, Strain Effects on the Surface Chemistry of La_0.7Sr_0.3MnO₃, ECS Trans. 35 (2011) 2097-2104.
7. Heather L. Tierney, Jeong Woo Han, April D. Jewell, Erin V. Iski, Ashleigh E. Baber, David S. Sholl and E. Charles H. Sykes, Chirality and Rotation of Asymmetric Surface-Bound Thioethers, J. Phys. Chem. C 115 (2011) 897-901. Part of the “Alfons Baiker Festschrift”
8. Jeong Woo Han and David S. Sholl, Enantiospecific adsorption of amino acids on hydroxylated quartz (10-10), Phys. Chem. Chem. Phys. 12 (2010) 8024-8032.
9. Darin O. Bellisario, Jeong Woo Han, Heather L. Tierney, Ashleigh E. Baber, David S. Sholl, and E. Charles H. Sykes, Importance of Kinetics in Surface Alloying: A Comparison of the Diffusion Pathways of Pd and Ag Atoms on Cu(111), J. Phys. Chem. C 113 (2009) 12863-12869.
10. Jeong Woo Han and David S. Sholl, Enantiospecific Adsorption of Amino Acids on Hydroxylated Quartz (0001), Langmuir 25 (2009) 10737-10745.
11. Jeong Woo Han, John R. Kitchin, and David S. Sholl, Step decoration of chiral metal surfaces, J. Chem. Phys. 130 (2009) 124710.
12. Jeong Woo Han, Joanna N. James, and David S. Sholl, First principles calculations of methylamine and methanol adsorption on hydroxylated quartz (0001), Surf. Sci. 602 (2008) 2478-2485.