Geunsik Lee 교수

Using the ab initio density-functional theory method and local spin-density approximation, we calculated the electronic band structures of H or H2 edge-hydrogenated zigzag graphene nanoribbons (ZGNRs) as well as COH, CO, or C2O edge-oxidized ZGNRs. We found that the OH group yields almost the same band structure as the $s{p}^{2}$ hybridization of H edge, and that the ketone (CO) and ether (C2O) groups result in band structures similar to those of $s{p}^{3}$ hybridization of H2 edge. Compared to

We have investigated ozone adsorption on graphene using the ab initio density functional theory method. Ozone molecules adsorb on the graphene basal plane with a binding energy of 0.25 eV, and the physisorbed molecule can chemically react with graphene to form an epoxide group and an oxygen molecule. The activation energy barrier from physisorption to chemisorption is 0.72 eV, and the chemisorbed state has the binding energy of 0.33 eV. These binding energies and energy barrier indicate that the

Carbon-based transition metal (TM) single-atom catalysts (SACs) have shown great potential toward electrochemical water splitting and H 2 production.

Abstract MXenes have been widely used as substrates of hybrid electrocatalysts for water splitting due to their stability and metallic properties. However, tuning MXenes towards superb hydrogen/oxygen evolution reaction (HER/OER) activity has remained elusive. Using first‐principles calculations along with machine learning (ML) based descriptors, it is shown that late transition metal doping is able to significantly promote HER/OER activities. Both single‐atom adsorption onto a stable hollow sit

Low-energy electronic structures in $A$MnBi${}_{2}$ ($A$=alkaline earths) are investigated using a first-principles calculation and a tight binding method. An anisotropic Dirac dispersion is induced by the checkerboard arrangement of $A$ atoms above and below the Bi square net in $A$MnBi${}_{2}$. SrMnBi${}_{2}$ and CaMnBi${}_{2}$ have a different kind of Dirac dispersion due to the different stacking of nearby $A$ layers, where each Sr (Ca) of one side appears at the coincident (staggered) $xy$

The catalytic activity and selectivity can be improved for nitrogen fixation by using hollow sites and vacancy defects in 2D materials, while a new machine learning descriptor accelerates screening of efficient electrocatalysts.

A powerful synthetic protocol based on a molecularly engineered anchoring carbon platform (ACP) is reported to stabilize concentrated edge-hosted single-atom catalytic sites of M–N (M = Fe, Co, Ni, Cu) on carbon supports. Polymerization with l-cysteine as an additional organic precursor produces an ACP sheath around the carbon nanotube (CNT)–graphene (GR) hybrid support made of a small domain size with abundant edge sites and doped with sulfur. A few-minute-long microwave pyrolysis anchors stron

Covalent organic frameworks (COFs) have emerged as a promising platform for photocatalysts. Their crystalline porous nature allows comprehensive mechanistic studies of photocatalysis, which have revealed that their general photophysical parameters, such as light absorption ability, electronic band structure, and charge separation efficiency, can be conveniently tailored by structural modifications. However, further understanding of the relationship between structure-property-activity is required

Based on the dynamical mean field theory and angle resolved photoemission spectroscopy, we have investigated the mechanism of high T(c) superconductivity in stoichiometric LiFeAs. The calculated spectrum is in excellent agreement with the measured angle resolved photoemission spectroscopy. The Fermi surface (FS) nesting, which is predicted in the conventional density functional theory method, is suppressed due to the orbital-dependent correlation effect within the dynamical mean field theory met

The synergistic interplay between surface negative charges and functional groups in the carbon dot establish a strong Li-ion affinity, resulting in homogeneous Li deposition.

To tune single-atom catalysts (SACs) for effective nitrogen reduction reaction (NRR), we investigate various transition metals implanted on boron-arsenide (BAs), boron-phosphide (BP), and boron-antimony (BSb) using density functional theory (DFT). Interestingly, W-BAs shows high catalytic activity and excellent selectivity with an insignificant barrier of only 0.05 eV along the distal pathway and a surmountable kinetic barrier of 0.34 eV. The W-BSb and Mo-BSb exhibit high performances with limit

First principles calculations are used to systematically screen promising catalysts for water splitting and metal–air batteries. We find that a single atom (Ni/Fe/Cu) embedding into MXenes is able to promote HER, OER, and ORR.

The effects of air temperature and sample thickness on drying kinetics of strawberry fruit leather were investigated. The mathematical modeling was performed by using three thin-layer drying models. The independent variables were sample thickness (1.8, 2.7, and 3.6 mm) and air temperature (50C, 60C, 70C, and 80C). Drying took place in the falling rate period. The values of effective moisture diffusivity (Deff) varied from 2.40 10-9 to 12.1 10-9 m2 s-1 depending on drying conditions. The values o