Hyunseob Lim

Hyunseob Lim
Gwangju Institute of Science and Technology · Department of Chemistry (Graduate School)

Ph.D

About

63
Publications
16,696
Reads
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2,031
Citations
Citations since 2017
24 Research Items
1538 Citations
2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
Additional affiliations
March 2014 - present
Ulsan National Institute of Science and Technology
Position
  • Professor (Associate)
March 2012 - March 2014
RIKEN
Position
  • PostDoc Position
March 2006 - February 2011
Pohang University of Science and Technology
Position
  • PhD Student

Publications

Publications (63)
Article
We report on an insulating two-dimensional material, hexagonal boron nitride (h-BN), which can be used as an effective wrapping layer for surface-enhanced Raman spectroscopy (SERS) substrates. This material exhibits outstanding characteristics such as its crystallinity, impermeability, and thermal conductance. Improved SERS sensitivity is confirmed...
Article
The authors present a new analytical method to determine the most important two parameters, rotational angle (Rθ) and strain (Δa Gr/a Gr) of graphene on metal substrate, from scanning tunneling microscope images. Epitaxial graphene on Ir(111) and Pt(111) was investigated by this method, which demonstrates that rotational angle and strain are not in...
Article
Large-scale growth of high-quality hexagonal boron nitride has been a challenge in two-dimensional-material-based electronics. Herein, we present wafer-scale and wrinkle-free epitaxial growth of multi-layer hexagonal boron nitride on a sapphire substrate by using high-temperature and low-pressure chemical vapor deposition. Microscopic and spectrosc...
Article
Full-text available
Graphene-based carbon materials such as fullerenes, carbon nanotubes, and graphenes have distinct and unique electronic properties that depend on their dimensionality and geometric structures. Graphene wrinkles with pseudo one-dimensional structures have been observed in a graphene sheet. However, their one-dimensional electronic properties have ne...
Article
Heterostructures of hexagonal boron nitride (h-BN) and graphene have attracted a great deal of attention for potential applications in 2D materials. While several methods have been developed to produce this material through the partial substitution reaction of graphene, the reverse reaction has not been reported. While the endothermic nature of thi...
Article
A highly reproducible route for the epitaxial growth of single-crystalline monolayer MoS2 on a C-plane sapphire substrate was developed using vapor-pressure-controllable inorganic molecular precursors MoOCl4 and H2S. Microscopic, crystallographic, and spectroscopic analyses indicated that the epitaxial MoS2 film possessed outstanding electrical and...
Article
In plane micro‐supercapacitors (mSCs) that are miniaturized energy‐storage components have attracted significant attention due to their high‐power densities for various ubiquitous and sustainable device systems as well as their facile integration on various flexible/wearable platform. To implement the mSCs in various practical applications that can...
Article
Bandgap engineering is an important prerequisite for various applications of two‐dimensional (2D) transition metal dichalcogenides (TMD). A reduction in the dimension from 2D has been one of the methods to control the electronic structure, by which a quantum confinement effect in the additional axis(es) can result in the widening of band structures...
Preprint
Full-text available
A graphene nanowrinkle (GNW) formed on a Ni substrate, with a width below 5 nm, exhibits a unique feature (van Hove singularities (vHS)) in its electronic structure, owing to the one-dimensional (1D) electron confinement in GNWs. Considering that the 1D electron confinement effect normally appears when the electron motion is isolated in a 1D struct...
Article
A chemical route for the growth of centimeter-scale and homogeneous WS2 monolayer has been developed using the penta-coordinated inorganic W complex, WOCl4. The relatively low melting point of WOCl4 compared to other conventional W precursors enables the use of WOCl4 as a vapor phase precursor. Consequently, the precise control of partial pressure...
Article
We report facile growth methods for high-quality monolayer and multilayer MoS2 films using MoOCl4 as the vapor-phase molecular Mo precursor. Compared to the conventional covalent solid-type Mo precursors, the growth pressure of MoOCl4 can be precisely controlled. This enables the selection of growth mode by adjusting growth pressure, which facilita...
Article
Photoexcited electron extraction from semiconductors can be useful for converting solar energy into useful forms of energy. Although InP quantum dots (QDs) are considered alternative materials for solar energy conversion, the inherent instability of bare InP QDs demand the use of passivation layers such as ZnS for practical applications, which impe...
Article
Although surface engineering has been regarded to be a great approach to modulate the optical and electrical properties of nanomaterials, the spontaneous covalent functionalization on semiconducting 2H-MoS2 is a notoriously difficult process, while several reactions have been performed on metallic 1T-MoS2. This limitation in functionalization is at...
Article
Full-text available
Nickel(II) dichloride complexes with a pyridine-chelated imidazo[1,5-a]pyridin-3-ylidene py-ImPy ligand were developed as novel catalyst precursors for acrylate synthesis reaction from ethylene and carbon dioxide (CO2), a highly promising sustainable process in terms of carbon capture and utilization (CCU). Two types of ImPy salts were prepared as...
Article
Since a graphene sheet consists of unsaturated sp2 carbon bonds, the addition reaction for the saturating aromatic bonds can lead to a variety of non-natural two-dimensional (2D) materials. However, despite many interests and numerous efforts, it has not been possible to synthesize a noble stoichiometric 2D crystal by chemically modifying a graphen...
Article
Facile in situ Synthesis of Ag-Doped CdSe Supra-Quantum Dots and their Characterization
Article
Demonstration of graphene growth on metal substrates using chemical vapor deposition method (CVD) facilitated the large-area synthesis of graphene, which extended the graphene research from the fundamental investigation with a small graphene flake to the various practical applications. Spectroscopic studies using ¹³C-labeled carbon precursor first...
Article
An atomically thin two-dimensional (2D) covalent organic framework (COF) was successfully synthesized via photon-assisted imine condensation reaction within 1 h from the highly uniform and homogeneous precursor solution layer floating on the water surface. The polarity optimization of the precursor solution was the key step for the successful forma...
Article
We investigated the temperature-dependent photoluminescence (PL) properties of colloidal CsPbX3 (X = Br, I, and mixed Br/I) quantum dot (QD) samples in the 30–290 K temperature range. Temperature-dependent PL experiments reveal thermal quenching of PL, blue shifting of optical band gaps, and linewidth broadening for all CsPbX3 QD samples with incre...
Article
Despite potential advantages of covalent organic frameworks (COFs) in wide area applications, several limitations in conventional solvothermal synthesis, such as long reaction time and high reaction temperature, reduce reaction efficiency and prohibit technical processes for practical applications. Therefore, the development of a novel synthesis me...
Article
Full-text available
Synthesis of morphologically well-defined crystals of metalloporphyrin by direct crystallization based on conventional anti-solvent crystallization method without using any additives has been rarely reported. Herein, we demonstrate an unconventional and additive-free synthetic method named reverse anti-solvent crystallization method to achieve well...
Article
Full-text available
Interlayer excitons were observed at the heterojunctions in van der Waals heterostructures (vdW HSs). However, it is not known how the excitonic phenomena are affected by the stacking order. Here, we report twist-angle-dependent interlayer excitons in MoSe2/WSe2 vdW HSs based on photoluminescence (PL) and van der Waals-corrected density functional...
Article
Full-text available
Folded graphene in which two layers are stacked with a twist angle between them has been predicted to exhibit unique electronic, thermal, and magnetic properties. We report the folding of a single crystal monolayer graphene film grown on a Cu(111) substrate by using a tailored substrate having a hydrophobic region and a hydrophilic region. Controll...
Article
The electronic and magnetic properties of chemically modified graphene armchair edges are studied using a combination of tight-binding calculations, first-principles modelling, and low temperature scanning tunneling microscopy (STM) experiments. The atomically resolved STM images of the hydrogen etched graphitic edges suggest the presence of locali...
Article
Various solid carbon sources, particularly poly(methyl methacrylate), have been used as precursors to graphene. The corresponding growth process generally involves the decomposition of the solids to hydrocarbon gases followed by their adsorption on metallic substrates (e.g., Cu). We report a different approach that uses a thermally-resistant polyim...
Article
Transition metal dichalcogenides (TMDs) have recently received increasing attention because of their potential applications in semiconducting and optoelectronic devices exhibiting large optical absorptions in the visible range. However, some studies have reported that the grain boundaries of TMDs can be easily degraded by the presence of oxygen in...
Article
A novel type of action spectrum representing multiple overtone excitations of the v(M−C) mode was observed for lateral hopping of a CO molecule on Ag(110) induced by inelastically tunneled electrons from the tip of a scanning tunneling microscope. The yield of CO hopping shows sharp increases at 261±4 mV, corresponding to the C-O internal stretchin...
Article
Full-text available
We synthesized single-phase CoS2 on a large scale by adding graphene oxide of sufficient quantity via the hydrothermal method using cobalt acetate and thioacetamide as precursors; this produced the hybrid of CoS2 with reduced graphene oxide which exhibited high electrocatalytic activity in the hydrogen evolution reaction. Electronic supplementary...
Article
Full-text available
We synthesized single-phase CoS 2 on a large scale by adding graphene oxide of sufficient quantity via the hydrothermal method using cobalt acetate and thioacetamide as precursors; this produced the hybrid of CoS 2 with reduced graphene oxide which exhibited high electrocatalytic activity in the hydrogen evolution reaction.
Data
Supplementary Figures 1-12, Supplementary Table 1, Supplementary Notes 1-3 and Supplementary References
Article
Full-text available
Using scanning tunneling microscopy, we observe an adlayer structure that is dominated by short rows of S atoms, on unreconstructed regions of a Au(111) surface. This structure forms upon adsorption of low S coverage (less than 0.1 monolayer) on a fully reconstructed clean surface at 300 K, then cooling to 5 K for observation. The rows adopt one of...
Article
Full-text available
A rich menagerie of structures is identified at 5 K following adsorption of low coverages (≤0.05 monolayers) of S on Cu(111) at room temperature. This paper emphasizes the reconstructions at the steps. The A-type close-packed step has 1 row of S atoms along its lower edge, where S atoms occupy alternating pseudo-fourfold-hollow (p4fh) sites. Additi...
Article
Full-text available
Sulfur-metal complexes, containing only a few atoms, can open new, highly efficient pathways for transport of metal atoms on surfaces. For example, they can accelerate changes in the shape and size of morphological features, such as two-dimensional nanoclusters, over time. In this study we perform STM under conditions that are designed to specifica...
Article
Along With the explosive interest in graphene research, much attention has been paid to other two-dimensional (2D) materials such as transition Metal dithalcogenides (TMDs) and hexagonal boron nitride (h-BN). In particular the stacking of various 2D materials in the vertical and lateral directions has been studied recently, as novel physicochemical...
Article
We have carried out an extensive DFT-based search for the structure of the (√43 × √43)R ± 7.5° reconstruction of S on Cu(111), which exhibits a honeycomb-type structure in scanning tunneling microscopy (STM). We apply two criteria in this search: The structure must have a reasonably low chemical potential, and it must provide a good match with STM...
Article
Graphene functionalization is of great importance in applying graphene as a component into a variety of functional devices or in activating itself for graphene-based catalysts. Here we reveal that atomic oxidation of epitaxial graphene grown on a metal substrate results in the formation of enolate, i.e., adsorption of atomic oxygen at ontop positio...
Article
Contrary to the general understanding, direction controlled epitaxial graphenes with an identical rotational angle (R θ = R0) is reported. Despite the identical Rθ, various Moire patterns with different periodicity are observed, which cannot be understood by conventional Rθ dependence. A new method is suggested for practical analysis, in which degr...
Article
Understanding of electrochemical process in rechargeable Li–O2 battery has suffered from lack of proper analytical tool, especially related to the identification of chemical species and number of electrons involved in the discharge/recharge process. Here we present a simple and straightforward analytical method for simultaneously attaining chemical...
Article
Full-text available
Metal catalyst-free growth of large scale single layer graphene film on a sapphire substrate by a chemical vapor deposition (CVD) process at 950 °C is demonstrated. A top-gated graphene field effect transistor (FET) device is successfully fabricated without any transfer process. The detailed growth process is investigated by the atomic force micros...
Article
A direct and metal layer-free growth of flat graphene pads on exfoliated hexagonal boron nitride substrate (h-BN) are demonstrated by atmospheric chemical vapour deposition (CVD) process. Round shape with high flatness graphene pads are grown in high yield (∼95%) with a pad thickness of ∼0.5 nm and homogenous diameter.
Article
Full-text available
Single-layer graphene (SLG) shows an anomalously large surface charging effect during scanning photoelectron microscopy (SPEM), which is distinguished from bi-layer graphene (BLG). The different behaviour is believed due to a different screening effect for SLG and BLG.
Article
Because the direct formation of large, patterned graphene layers on active electronic devices without any physical transfer process is an ultimate important research goal for practical applications, we first developed a cost-effective, scalable, and sustainable process to form graphene films from solution-processed common polymers directly on a SiO...
Article
Spontaneous oxidation of C60 by Au ions was observed. When C60 was guided to make contacts with Au3+ ions in aqueous HAuCl4 solution, electrons were spontaneously transferred from C60 to Au3+ ions, resulting in hole (h+) doped C60 cations and Aunanoparticles on a C60 layer. This spontaneous electron transfer occurs due to the galvanic displacement...
Article
The site-dependent and spontaneous functionalization of 4-bromobenzene diazonium tetrafluoroborate (4-BBDT) and its doping effect on a mechanically exfoliated graphene (MEG) were investigated. The spatially resolved Raman spectra obtained from both edge and basal region of MEG revealed that 4-BBDT molecules were noncovalently functionalized on the...
Article
A Au-coated C(60) wire device showed wavelength-selective silencing of photocurrent on illumination with 532 nm light.
Article
A single walled carbon nanotube (SWNT) Schottky diode was fabricated via selective electrochemical metal deposition on a prefabricated SWNT field effect transistor device. By electrochemically depositing Pd on only one of the prepatterned Ti electrodes, asymmetric Ohmic (at Pd-SWNT) and Schottky (at SWNT-Ti) contacts were resolved, resulting in eff...
Article
Full-text available
Liquid GeCl(4) precursors have been employed to grow into one dimensional Ge nanowires (NWs) via a vapor-liquid-solid (VLS) process, in which Si, supplied as a form of liquid SiCl(4), plays a critical role for the successful formation of Ge NWs.
Article
A study was conducted to demonstrate a new spontaneous hydrosilylation reaction that induced direct carbon-silicon (C-Si) bonds using silane compounds containing a neutral Si-Hx moiety. The study aimed at demonstrating that covalent bonds readily formed between triethysilane (TriES) and single-walled nanotubes (SWNT) at room temperature through a s...
Article
We have developed a process to convert C(60) nanostructures into graphitic nanostructures. Disk-shaped and wire-shaped C(60) nanostructures synthesized by the liquid-liquid interfacial precipitation method, the vapor-solid process, and solvent evaporation were successfully converted into graphitic structures by thermal annealing in hydrogen at 900...
Article
Full-text available
Single-walled carbon nanotubes (SWNTs) have been investigated as a key potential candidate for high performance electronic devices. Two representative device forms are carbon nanotube based field effect transisotors (FETs) and diodes. In contrast of high popularity of FET devices for the fundamental studies as well as applications, carbon nanotube...
Article
2001 to 2003. Since then, he has been working as an assistant (2003–2005) and associate (2006–now) pro-fessor in Physics Department at Seoul National University. His re-search fields include molecular electronics, dip-pen nanolithography, self-assembly, surface-programmed assembly, carbon nanotube electronics, nano-biosensors, nanoscale tissue engi...
Article
We developed a facile chemical route by which single-waited carbon nanotube (SWNT) Schottky diodes are realized. When a bias voltage was applied to a lithium ion intercalated SWNT field effect transistor (FET) device, lithium ions intercalated between 1-pyronmethylamine (1-PMA), and SWNTs are migrated to the drain (-) electrode to be reduced at the...
Article
Full-text available
A successful combination of “oxygen-assisted chemical vapor deposition (CVD) process” and Co catalyst nanoparticles to grow highly pure single walled carbon nanotubes (SWNTs) was demonstrated. Recently, it was reported that addition of small amounts of oxygen during CVD process dramatically increased the purity and yield of carbon nanotubes. Howeve...
Article
A reproducible negative differential resistance (NDR) behavior with symmetric peaks was observed from the planar-type metalloproteins (ferritins) devices utilizing metallic single walled carbon nanotube (SWNT) nanogap electrodes. The SWINIT nanogap electrodes were fabricated by electrically cutting metallic SWNTs, between which ferritins were captu...

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Project (1)
Project
Now, I am working on TMD based heterostructures. You can contact me in my e-mail i.d. pramod_phy@yahoo.com to know more details.