Our research interest lies in the broad field of computational and theoretical nanoscience – Bridging materials science, condensed matter physics, and solid-state chemistry. In particular, we focus on four areas of computational materials research:
Nanothermodynamics: Ab initio atomistic thermodynamics
Understanding of the complex behavior of particles at surfaces requires detailed knowledge of both macroscopic and microscopic processes that take place; also certain processes depend critically on temperature and gas pressure (e.g. corrosion and heterogeneous catalysis). Extensive density-functional theory (DFT) calculations, and taking into account temperature and pressure through consideration of the chemical potential of the gas species, affords a comprehensive picture of the behavior and interaction between a gas and a solid surface.
- A. Soon, M. Todorova, B. Delley, and C. Stampfl, Oxygen adsorption and stability of surface oxides on Cu(111): A first-principles investigation, Phys. Rev. B 73, 165424 (2006) [pdf]
- C. Stampfl, A. Soon, S. Piccinin, H. Q. Shi and H. Zhang, Bridging the temperature and pressure gaps: Close-packed transition metal surfaces in an oxygen environment, J. Phys.: Conden. Matter. 20, 184021 (2008) [pdf]
- N. A. Richter, C.-E. Kim, C. Stampfl, and A. Soon, Revisiting the O/Cu(111) system – When metastable surface oxides could become an issue!, Phys. Chem. Chem. Phys. 16, 26735 (2014) [pdf, arXiv]
- Y. Min, J. Kwak, A. Soon, and U. Jeong, Nonstoichiometric nucleation and growth of multicomponent nanocrystals in solution, Acc. Chem. Res. 47, 2887 (2014) [pdf]
- T. Lee, Y. Lee, S. Piccinin, and A. Soon, Ab initio thermodynamics of surface oxide structures under controlled growth conditions, J. Phys. Chem. C 121, 2228 (2017) [pdf]
The Gibbs–Wulff theorem provides a mathematical construction that predicts the equilibrium crystal shape (ECS) of crystals or nanoparticles, whereby the total free energy of the crystal is at a minimum at a constant volume. Our group is interested to extend this thermodynamic model to describe substrate-supported nanoparticles, particularly for nanocatalysis application.
- T.-H. Lee, B. Delley, C. Stampfl, and A. Soon, Environment-dependent nanomorphology of TiN: Influence of surface vacancies, Nanoscale 4, 5183 (2012) [pdf]
- S.-H. Yoo, J.-H. Lee, B. Delley, and A. Soon, Why does bromine square palladium off? An ab initio study of brominated palladium and its nanomorphology, Phys. Chem. Chem. Phys. 16, 18570 (2014) [pdf]
- Y. Kwon, A. Soon, H. Han, and H. Lee, Shape effect of cuprous oxide particles on stability in water and photocatalytic water-splitting, J. Mater. Chem. A 3, 156 (2015) [pdf]
- S.-H. Yoo, J.-H. Lee, Y.-K. Jung, and A. Soon, Exploring stereographic surface energy maps of cubic metals via an effective pair-potential approach, Phys. Rev. B 93, 035434 (2016) [pdf]
- G. Park, J. Lee, S. Moon, H. Yang, A. Giri, J. Kwak, Y.-K. Jung, A. Soon, and U. Jeong, Eventual chemical transformation of metals and chalcogens into metal chalcogenide (M2X3) nanoplates through surface nucleation-detachment-reorganization mechanism, Chem. Mater. 29, 3219 (2017) [pdf]
Nanocatalysis by design:
Synergistic co-operative effects
One important area of catalysis that is developing at an extremely rapid pace is nanocatalysis. Striking novel catalytic properties including greatly enhanced reactivities and selectivities have been reported for nanoparticle catalysis as compared to their bulk counterparts.
In an attempt to alleviate the high-cost associated with conventional proton exchange membrane fuel cell (PEMFC) catalysts and to further maximize its catalytic activity and durability, we propose a promising route to design the next generation of Pt-based PEMFC nanocatalysts with single-Pt atom dispersions and to replace the easily degraded carbon support with the more durable non-conventional conducting supports, in hope to improve the lifetime of these PEMFCs.
- R. Q. Zhang, T.-H. Lee, B.-D. Yu, C. Stampfl, and A. Soon, The role of titanium nitride supports for single-atom platinum-based catalysts in fuel cell technology, Phys. Chem. Chem. Phys. 14, 16552 (2012) [pdf]
- R. Q. Zhang, C.-E. Kim, B.-D. Yu, C. Stampfl, and A. Soon, Mitigation of CO poisoning on functionalized Pt/TiN surfaces, Phys. Chem. Chem. Phys. 15, 19450 (2013) [pdf]
- S. Yang, D. Y. Chung, Y.-J. Tak, J. Kim, H. Han, J.-S. Yu, A. Soon, Y.-E. Sung, and H. Lee, Electronic structure modification of platinum on titanium nitride resulting in enhanced catalytic activity and durability for oxygen reduction and formic acid oxidation, Appl. Catal. B: Environ. 174, 35 (2015) [pdf]
- S. Yang, J. Kim, Y.-J. Tak, A. Soon, and H. Lee, Single-atom catalyst of platinum supported on titanium nitride for selective electrochemical reactions, Angew. Chem. Int. Ed. 55, 2058 (2016) [pdf]
- S. Yang, Y.-J. Tak, J. Kim, A. Soon, and H. Lee, Support effect in single-atom platinum catalyst for electrochemical oxygen reduction, ACS Catal. 7, 1301 (2017) [pdf]
Nanoelectronics: Bandgap engineering at the nanoscale
Nanoscale semiconductors exhibit clear tuneable size- and shape-dependent optical and electronic properties. These nanostructures bridge the gap between small molecules and large crystals, displaying discrete electronic energy states of isolated atoms and molecules, as well as enabling the exploitation of the useful properties of semiconducting materials.
In addition, nano-interfaces are boundaries between two phases where the properties or behavior of nanomaterial differ from those of the adjoining phases. Engineering of these nano-interfaces play an important role in our daily life, and in the world around us. The recent developments in modern technologies involve new nanomaterials and processes in which nano-interfaces play a crucial role.
- T.-I. Lee, S.-H. Lee; Y.-D. Kim, W.-S. Jang, J.-Y. Oh, H.-K. Baik, C. Stampfl, A. Soon, and J.-M. Myoung, Playing with dimensions: Rational design for hetero-epitaxial p-n junctions, Nano Lett. 12, 68 (2012) [pdf, suppm]
- W. Jang, K. Kang, and A. Soon, Remarkably low-energy one-dimensional fault line defects in single-layered phosphorene, Nanoscale 7, 19073 (2015) [pdf, arXiv]
- W. Jang, K. Kang, and A. Soon, Acute mechano-electronic responses in twisted phosphorene nanoribbons, Nanoscale 8, 14778 (2016) [pdf]
- J. Yun, W. Jang, T. Lee, Y. Lee, and A. Soon, Aligning the band structures of polymorphic molybdenum oxides and organic emitters in light-emitting diodes, Phys. Rev. Applied 7, 024025 (2017) [pdf]
- A. Giri, H. Yang, K. Thiyagarajan, W. Jang, J.-M. Myoung, R. Singh, A. Soon, K. Cho, and U. Jeong, One-step solution phase growth of transition metal dichalcogenide thin films directly on solid substrates, Adv. Mater. 29, 1700291 (2017) [pdf]