Bio:

Hyungjun Kim is an associate professor of Department Chemistry at Korea Advanced Institute of Science and Technology (KAIST). He received his B.S. degree in Chemistry in 2004 from KAIST. He obtained his Ph.D. in Chemistry in 2009 from Caltech under the supervision of Prof. William A. Goddard, III. on the development of multiscale and multiphysics computational framework for nano- and bio-systems. After 3.5 year of senior researcher position at KAIST, he started his faculty position at KAIST in 2013 and was promoted to associate professor in 2016. He is an author of more than 190 peer-reviewed journal papers (H-index 54, total citations > 11,400, according to Google Scholar), and now also a junior member of the Korean Academy of Science and Technology. His main research interest is in developing new computational methods (e.g., DFT-CES, vdW-corrected DFT method, etc.) to elucidate the complex molecular mechanism of materials and thereby to design new functional materials.

Abstract:

Electrochemistry, the fundamental basis of sustainable energy conversion technologies, investigates the electric-chemical energy interconversion process at the electrode-electrolyte interface, where a characteristic liquid structure, namely an electric double layer (EDL) is known to be formed. Since the early 1900s, when the concept of EDL was theoretically formulated, unremitting efforts have been made to identify potential-dependent EDL structural changes, but only a few molecular details have been disclosed to date. One famous example is EDL capacitance, an indicative quantity of the EDL structural change, which shows two characteristic peaks in a dilute electrolyte, but no molecular theory of liquid structure has fully explained them. To address this century-long debate by accurately modeling the electrified interface, we develop a first-principles-based multiscale method called a density functional theory in classical explicit solvents (DFT-CES), which mean-field couples the DFT and the molecular dynamics for respective description of electrode and electrolyte. Using DFT-CES, we find unprecedented liquid structural changes and phase transitions of the EDL, which originate two capacitance peaks at the same potentials to the experiment. Atom-level investigation on the EDL region, enabled by our DFT-CES simulations, further unravels a new mechanistic role of the cations in the EDL during CO2 electroreduction (which is also verified by experimental kinetic study) - they are no more spectating the reaction but are coordinating to key intermediates for a cation-coupled electron transfer. Our studies envisage a new perspective for developing better electrocatalysts by tailoring the electrochemical interface.

Please contact: @Seung Soon Jang (seungsoon.jang@mse.gatech.edu) for more information