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Dr. Heechae Choi

  • Ph. D. Heechae Choi Group Leader (Principal Investigator) Institute of Inorganic Chemistry

    Greinstr. 6 50939 Cologne Germany
    • Theoretical Materials & Chemistry Group
    • IndependentGroupLeader
    Contact via E-Mail

Research Interests

  • Machine learning based discovery of environmental and energy materials
  • Developing solar energy conversion theory
  • Ceramic processing for water purifications
  • Durability and corrosion-resistivity improvements for environmental and energy materials

Research Topics

I. Electrodynamics into electrochemistry for advanced catalyst design

  • Implementation of electrodynamics into conventional catalysts design theory for advanced the catalyst designs with considerations of heterojunction, dynamic condition, durability, and selectivity, which have not been well considered before.
  • Experiments and computations are combined to accelerate the understanding and the developments of high-performance catalysts.

II. Experimental and mathematical study on optoelectronic materials design

  • I love to make mathematical models to deeply understand the frequently overlooked materials property change with processing conditions, which is followed by experiments to complete the validity of the models.

III. Semiconductor device and materials processing

  • Using theory models and multi-scale simulations, I have solved industrial problems in semiconductor manufacturing line.
  • One of my strong research interests is prediction of device lifetime and performances based on mass transfer, heat transfer, and quantum mechanics.

IV. Semiconductor defects and photochemistry

  • Carrier transport and photochemistry of semiconductors with point defects
  • Theoretical predictions of defect equilibria predictions experimental verifications

Important Grants

  • DAAD Grant (MOPGA-GRI), (Sep.2018-Aug.2022), 1Million Euro
  • Research Council of Fundamental Science and Technology (KRCF) (May2012-Apr.2015), 150Million KRW

Project Funding as PI

  • Samsung Electronics network device quality control (Dec.2018-Mar.2019) – Samsung
  • Apple Inc’s Antenna Materials Processing (Oct.2017 – Sep.2018) - KITECH
  • Samsung Electromechanics capacitor lifetime prediction (May.2019-Oct.2019) - Samsung
  • Piezoelectric materials screening with computations (Apr. 2021-May2021) - KICET
  • Solid state electrolyte development for Li-ion battery (Oct.2021-Dec.2021) -KICET
  • Parderborn Center for Parallel Computing (PC2) (Oct. 2020-Sep.2021)
  • QM2 Grant implemented in University of Cologne (German excellence initiative by DFG)
  • SPARC Project (India-Germany) (2019-2021) – India Government

Computation skills

  • Density functional theory (DFT) calculations (VASP)
  • Time-dependent DFT (TDDFT) calculations
  • Finite element method (FEM)

Paper Publications

<Book chapter>

1. F. Ünlü, E. Jung, S. Öz, Heechae Choi, T. Fischer, S. Mathur, “Chemical Processing of Mixed-Cation Hybrid Perovskites: Stabilizing Effects of Configurational Entropy”, Perovskite Solar Cells: Materials, Processes, and Devices, 2021, p.1-p.31.


<Peer-reviewed journal publications>


  1. A. K. Singh+, S. Ji+, B. Singh, C. Das, Heechae Choi*, P. W. Menezes*, A. Indra*, “Alkaline Oxygen Evolution:  Exploring Synergy between fcc and hcp Cobalt Nanoparticles Entrapped in N-doped Graphene”, Mater. Today Chem., 2022, In press.
  2. Y. Sim, H. Cha, S. Surendran, M. Je, H. Choi, S. Yoo, D. C. Seok, Y. H. Jung, C. Jeon, D. J. Kim, M.-K. Han, Heechae Choi*, U. Sim*, J. Moon*, “Fluorine-doped Graphene Oxide Prepared by Direct Plasma Treatment for Supercapacitor Applications” Chem. Eng. J., 2022, In press.
  3. M. Je, H.-Y. Ahn, M. Dreger, H. Cho, C. Kim, J. Kim, S.-H. Cho, Heechae Choi*, “Using Miscibility Gap of Anion-mixed Metal Chalcogenide for Effective Band Gap Engineering with Temperature: Density functional theory and experimental study”, Solar RRL, 2022, In a minor revision.



  1. S. Khan, M. Je, N. N. Thanh Ton, W. Lei, T. Taniike, S. Yanagida, D. Ogawa, N. Suzuki, C. Terashima, A. Fujishima, Heechae Choi*, K. Katsumata*, “C-doped ZnS-ZnO/Rh Nanosheets as Multijunctioned Photocatalysts for Effective H2 Generation from Pure Water under Solar Simulating Light” Appl. Catal. B: Environ., 2021, 297, 120473.
  2. L. Pasqualini, M. Je, H. Huppertz, Heechae Choi, J. Bruns, “Triple Vertex Linkage of (BO4)-Tetrahedra in a Borosulfate: Synthesis, Crystal Structure, and Quantum Chemical Investigation of Sr[B3O(SO4)4(SO4H)]” Angew. Chem., 2021, 60, 1.
  3. Heechae Choi, T. Kim, H. Park, “Defect Engineering of TiNb2O7 compound for enhanced Li-ion battery anode performances”, Electrochim. Acta, 2021, In press.
  4. M. Kim+, J. Lee+, M. Je+, B. Heo, H. Yoo, Heechae Choi*, J. Choi*, K. Lee*, “Electric Field-driven One-step Formation of Vertical p-n Junction TiO2 Nanotube Having Strong Photocatalytic Hydrogen Production” J. Mater. Chem. A 2021, 9, 2239-2247.
  5. K. Chen+, S. Kim, M. Je+, Heechae Choi*, Z. Shi, N. Vladimir, K. H. Kim*, O. L. Li*, “Ultrasonic-Plasma Engineering toward Facile Synthesis of Single-Atom M-N4/N-doped carbon (M=Fe, Co) as Superior Oxygen Electrocatalyst in Rechargeable Zinc-Air Batteries”, Nano-Micro Letters, 2021, 13, 1-20.
  6. S. Kim, S. Ji, K. H. Kim, S. H. Roh, Y. Cho, C.-L. Lee, K.-S. Lee, D.-G. Choi, Heechae Choi*, J. K. Kim*, J. H. Park*, “Revisiting surface chemistry in TiO2: a critical role of ionic passivation for pH-independent and anti-corrosive photoelectrochemical water oxidation” Chem. Eng. J. 2021, 407, 126929.
  7. H. Nam, E. S. Sim, M. Je, Heechae Choi*, Y.-C. Chung*, “Theoretical Approach Toward Optimum Anion-doping on MXene Catalyst for Hydrogen Evolution Reaction: An Ab initio Thermodynamics Study” ACS Appl. Mater. Interfaces 2021, 13, 37035.
  8. J. Chang, T.-J. Ko, M. Je, H.-S. Chung, S. S. Han, M. S. Shawkat, M. Wang, S. J. Park, S. M. Yu, T.-S. Bae, M.-W. Moon, K. H. Oh, Heechae Choi, Y. Yang, Y. Jung, “Layer Orientation-Engineered Two-Dimensional Platinum Ditelluride for High-Performance Direct Alcohol Fuel Cells” ACS Energy Lett., 2021, 6, 3481-3487.
  9. Heechae Choi, H. Han, S.-I. Moon, M. Je, S. Lee, J. Kwon, S. Kim, K.-R. Lee, G. Ali, S. Mathur, U. Paik, S.-Z. Qiao, T. Song, “Strategy to utilize amorphous phase of semiconductor towards excellent and reliable photochemical water splitting performance: Roles of interface dipole moment and reaction parallelization”, Int. J. Energy Res., 2021, Accepted.



  1. S. Khan+, Heechae Choi+ (Co-first author), S. Kim, S.-H. Cho, “Self-assembled Heterojunction of Metal Sulfides for Improved Photocatalysis” Chem. Eng. J. 2020, 395, 125092.
  2. B. Park+, M. Je+, J. Oh*, Heechae Choi*, S.Y. Lee*, “Rationally designed CuSb1-xBixS2 as a promising photovoltaic material: theoretical and experimental study” Scr. Mater. 2020, 179, 107-112.
  3. S. Khan, D. Kim, M. Je, S. Lee, S.-H. Cho*, T. Song*, Heechae Choi*, “Mapping Point Defects of Brookite TiO2 for Photocatalytic Activity Beyond Anatase Phase and P25”, J. Phys. Chem. C 2020, 124, 10376-10384.
  4. J. Woo, M. Je, Heechae Choi*, Y.-C. Chung, “Theoretical dopant screening and processing optimization for vanadium disulfide as cathode material for Li-air batteries: a density functional theory study”, Appl. Surf. Sci. 2020, 508, 145276.
  5. M. Je, E. S. Sim, J. Woo, Heechae Choi*, Y.-C. Chung*, “Manipulatable interface electric field and charge transfer in 2D/2D heterojunction photocatalyst via oxygen intercalation”, Catalysts 2020, 10, 469.
  6. T. Ludwig, M. Je, Heechae Choi, T. Fischer, S. Roitsch, R. Müller, R. S. Mane, K. H. Kim, S. Mathur, “Boosting nitrogen-doping and interlayer spacing in pre-reduced graphene oxide”, Nano Energy, 2020, Accepted.
  7. S. Dutta, H. Han, M. Je, Heechae Choi, J. Kwon, K. Park, A. Indra, K. M. Kim, U. Paik, T. Song, “Chemical and structural engineering of transition metal boride towards excellent and sustainable hydrogen evolution reaction” Nano Energy, 2020, 67, 104245.
  8. S. Kang, K. H. Jung, S. Mhin, Y. Son, K. Lee, W. R. Kim, Heechae Choi, J. H. Ryu, H. Han, K. M. Kim, “Fundamental Understanding of the Formation Mechanism for Graphene Quantum Dots Fabricated by Pulsed Laser Fragmentation in Liquid: Experimental and Theoretical Insight” Small, 2020, 16, 2003538.
  9. H. Han, A.K. Nayak, Heechae Choi, G. Ali, J. Kwon, S. G. Choi, U. Paik, T. Song, “Partial Dehydration in Hydrated Tungsten Oxide Nanoplates Leads to Excellent and Robust Bifunctional Oxygen Reduction and Hydrogen Evolution Reactions in Acidic Media” ACS Sustainable Chem. Eng. 2020, Accepted.
  10. F. Ünlü, E. Jung, J. Haddad, A. Kulkarni, S. Oez, Heechae Choi, T. Fischer, S. Chakraborty, T. Kirchartz, S. Mathur, “Understanding the interplay of stability and efficiency in A-site engineered lead halide perovskites”, APL Mater. 2020, Accepted.
  11. Y. K. Kshetri, T. Kamiyama, S. Torii, S. H. Jeong, T.-H. Kim, Heechae Choi, J. Zhou, Y. P. Feng, S. W. Lee, “Electronic structure, thermodynamic stability and high-temperature sensing properties of Er-α-SiAlON ceramics”, Sci. Rep. 2020, 10, 4952.
  12. O. L. Li, N. N. T. Pham, J. Kim, Heechae Choi, D. Lee, Y. Yang, W. Yao, Y.-R. Cho, S.G. Lee, “Insights on boosting oxygen evolution reaction performance via boron incorporation into nitrogen-doped carbon electrocatalysts” Appl. Surf. Sci. Accepted.
  13. S.-M. Yang, D.-S. Kim, Heechae Choi, K.-H. Kim, N.-M. Hwang, “Shape change of submicron nickel particles under hydrogen and nickel chloride vapor” Appl. Surf. Sci. 2020, 509, 145274.
  14. Woo Chul Ko, Kang Min Kim, Yong Jung Kwon, Heechae Choi, Jin Kuen Park, Young Kyu Jeong, “ALD-assisted synthesis of V2O5 nanoislands on SnO2 nanowires for improving NO2 sensing performance”, Appl. Surf. Sci. 2020, 509, 144821.
  15. D.-H. Lim, M. Kang, S.-Y. Jang, K. Hwang, I.-B. Kim, E. J., Y.-R. Jo, Y.-J. Kim, J. Kim, Heechae Choi, T.-W. Kim, S. Mathur, B.-J. Kim, D.-Y. Kim, ACS Appl. Mater. Interfaces, 2020, 12, 25066-25074.



  1. H. Han+, Heechae Choi+(+: Co-first author), S. Mhin, Y.-R. Hong, K. M. Kim, J. Kwon, G. Ali, K. Y. Chung, M. Je, K. Davey, S. Qiao, U. Paik, T. Song, “Advantageous Crystalline-Amorphous Phase Boundary for Enhanced Electrochemical Water Oxidation” Energy Environ. Sci. 2019, 12, 2443-2454 (Back Cover Article).
  2. Heechae Choi, Y. Kwon, H. Kim, Y. Jeong, “p-Type Conductivity in Hydrated Amorphous V2O5 and its Enhanced Photocatalytic Performance in ZnO/V2O5/rGO” ACS Appl. Electr. Mater. 2019, 1, 1881-1889 (Front Cover).
  3. H. Han, J. Woo, Y.-R. Hong, S. Mhin, K. M. Kim, J. Kwon, Heechae Choi*, Y.-C. Chung*, T. Song*, “Electronically Double‐Layered Metal Boride Hollow Nanoprism as an Excellent and Robust Water Oxidation Electrocatalysts” Adv. Energy Mater. 2019, 1803799 (Front Cover).
  4. Y. J. Kwon, H. W. Kim, W. C. Ko, Heechae Choi, Y.-H. Ko, and Y. K. Jeong, “Laser-engineered oxygen vacancies for improving the NO2 sensing performance of SnO2 nanowires” J. Mater. Chem. A, 2019, In press.
  5. J.-H. Hwang, M. A. Islam,  Heechae Choi, T. J. Ko, K. L. Rodriguez, H.-S. Chung, Y. Jung, W. H. Lee, “Improving Electrochemical Pb2+ Detection Using a Vertically Aligned 2D MoS2 NanofilmAnal. Chem. 2019, 91, 11770-11777 (Cover Article).
  6. Y.-R. Hong, S. Mhin, K. M. Kim, W.-S. Han, Heechae Choi, G. Ali, K. Y. Chung, H. J. Lee, S.-I Moon, S. Dutta, S. Sun, Y.-G. Jung, T. Song, H. Han, “Electrochemically activated cobalt nickel sulfide for an efficient oxygen evolution reaction: partial amorphization and phase control”, J. Mater. Chem. A, 2019, 7, 3592-3602 (Inside Cover Article)
  7. M. Choi, Heechae Choi, Y.-T. Kim, J. Ahn, “Material Design for Ge2Sb2Te5 Phase-change Material with Thermal Stability and Lattice Distortion” Scr. Mater. 2019, 170, 16-19.
  8. M. Choi, Heechae Choi, J. Ahn, and Y. T. Kim, “Interface-Driven Phase Transition of Phase-Change Material” Cryst. Growth. Des. 2019, 19. 2123-2130 (Front Cover).
  9. M. Wang, J. H. Kim, S. S. Han, M. Je, J. Gil, C. Noh, T.-J. Ko, K. S. Lee, D. I. Son. T.-S. Bae, H. I. Ryu, K. H. Oh, Y. J. Jung, Heechae Choi, H.-S. Chung, Y. Jung, “Structural Evolutions of Vertically Aligned Two-Dimensional MoS2 Layers Revealed by in Situ Heating Transmission Electron Microscopy” J. Phys. Chem. C, 2019, 123, 27843-27853.
  10. R. C. Pawar, S. Kang, H. Han, Heechae Choi, C. S. Lee, “In situ reduction and exfoliation of g-C3N4 nanosheets with copious active sites via a thermal approach for effective water splitting” Catal. Sci. Technol. 2019, 9, 1004.
  11. J. Leduc, Y. Goenuellue, P. Ghamgosar, S. You, J. Mouzon, Heechae Choi, A. Vomiero, M. Grosch, and S. Mathur, “Electronically-Coupled Phase Boundaries in α‑Fe2O3/Fe3O4 Nanocomposite Photoanodes for Enhanced Water Oxidation”, ACS Appl. Nano Mater. 2019, 2, 334-342.



  1. H. Han, K.M. Kim, Heechae Choi*, et al., “Parallelized Reaction Pathway and Stronger Internal Band Bending by Partial Oxidation of Metal Sulfide–Graphene Composites: Important Factors of Synergistic Oxygen Evolution Reaction Enhancement”, ACS Catal. 2018, 8, 4091 (Cover Article).
  2. H. Park, J. Kwon, Heechae Choi, D. Shin, T. Song, “Unusual Na+ Ion Intercalation/Deintercalation in Metal-Rich Cu1.8S for Na-Ion Batteries”, ACS Nano 2018, 12, 2827.
  3. Heechae Choi, Seong-I Moon, Taeseup Song, Seungchul Kim,”Hydrogen-free defects in hydrogenated black TiO2Phys. Chem. Chem. Phys. 2018, 20, 19871.




  1. Heechae Choi, S. Khan, J. Choi, D. T. T. Dinh, S. Y. Lee, U. Paik, S. H. Cho, S. Kim, “Synergetic control of band gap and structural transformation for optimizing TiO2 photocatalysts”App. Catal. B: Environ., 2017,210, 513.
  2. S. Khan, H. Cho, D. Kim, S. S. Han, K. H. Lee, S. H. Cho, T. Song, Heechae Choi*, “Defect engineering toward strong photocatalysis of Nb-doped anatase TiO2: Computational predictions and experimental verifications”, Appl. Catal. B: Environ. 2017,206, 520.
  3. H. Park, Heechae Choi, T. Song, and U. Paik, “Microstructural control of new intercalation layered titanoniobates with large and reversible d-spacing for easy Na+ ion uptake” Science Advances, 2017, 3, e1700509.
  4. Y.-W. Lee, B.-S. Kim, J. Hong, Heechae Choi, H.-S. Jang, B. Hou, S. Pak, J. Lee, S.-H. Lee, S. M. Morris, D. Whang, J.-P. Hong, “Hierarchically assembled tubular shell-core-shell heterostructure of hybrid transition metal chalcogenides for high-performance supercapacitors with ultrahigh cyclability” Nano Energy 2017, 37, 15.
  5. D. Kim, B. C. Yeo, D. Shin, Heechae Choi, S. Kim, N. Park, S. S. Han, “Dissimilar anisotropy of electron versus hole bulk transport in anatase TiO2: Implications for photocatalysis” Phys. Rev. B, 2017,95, 045209.
  6. S. Khan+, Heechae Choi+(+: Co-first author), S. Y. Lee, O. M. Ntwaeaborwa, S. Kim, and S.-H. Cho, “Unexpected roles of interstitially doped lithium in blue and green light emitting Y2O3:Bi3+: Combined experimental and computational study”, Inorg. Chem. 2017, 56, 12139-12147
  7. M. Choi+, Heechae Choi+(+: Co-first author), K.-R. Lee, S. Kim, Y. T. Kim, J. Ahn, “Effects of Y dopant on lattice distortion and electrical properties of In3SbTe2 phase-change material”, Phys. Status Solidi Rapid Res. Lett. 2017, 11, 1700275. (Front Cover)
  8. H. Cho, H. Son, D. Kim, M. Lee, S. B., H. Han, K. M. Kim, S. Kim, Heechae Choi*, T. Song*, K. H. Lee*, “Impact of Mg-doping site control in the performance of Li4Ti5O12 Li-ion battery anode: First-principles predictions and experimental verifications”J. Phys. Chem. C, 2017,121, 144207.
  9. H. Han, K. M. Kim, C.-W. Lee, Caroline S. Lee, R. Pawar, J. L. Jones, Y.-R. Hong, J.-H. Ryu, T. Song, S.H. Kang, Heechae Choi, and S. Mhin, Phys. Chem. Chem. Phys. 2017, 19, 28207-28215.



  1. Heechae Choi, D. Shin, B. C. Yeo, T. Song, S. S. Han, N. Park, S. Kim, “Simultaneously controllable doping sites and the activity of a W-N codoped TiO2 photocatalyst”, ACS Catal., 2016,6, 2745.
  2. J. Son, M. Choi, Heechae Choi, et al. “Structural evolution of graphene in air at the electrical breakdown limit” Carbon, 2016, 99, 466.


Full publication list: