Hyeon Suk Shin

Composite materials: Tungsten disulfide and WS2 /reduced graphene oxide (WS2 /rGO) nanosheets were fabricated by hydrothermal synthesis using tungsten chloride, thioacetamide, and graphene oxide (GO) as starting materials. The WS2 nanosheets are efficiently templated on the rGO layer. The WS2 /rGO hybrid nanosheets show much better electrocatalytic activity for the hydrogen evolution reaction than WS2 nanosheets alone.

Abstract MoS 2 becomes an efficient and durable nonprecious‐metal electrocatalyst for the hydrogen evolution reaction (HER) when it contains multifunctional active sites for water splitting derived from 1T‐phase, defects, S vacancies, exposed Mo edges with expanded interlayer spacings. In contrast to previously reported MoS 2 ‐based catalysts targeting only a single or few of these characteristics, the all‐in‐one MoS 2 catalyst prepared herein features all of the above active site types. During

The interaction between graphene and metal was investigated by studying the G band splitting in surface-enhanced Raman scattering (SERS) spectra of single-, bi-, and trilayer graphene. The Ag deposition on graphene induced large enhancement of the Raman signal of graphene, indicating SERS of graphene. In particular, the G band was split into two distinct peaks in the SERS spectrum of graphene. The extent of the G band splitting was 13.0 cm(-1) for single-layer, 9.6 cm(-1) for bilayer, and 9.4 cm

Hexagonal boron nitride (h-BN) is gaining significant attention as a two-dimensional dielectric material, along with graphene and other such materials. Herein, we demonstrate the growth of highly crystalline, single-layer h-BN on Pt foil through a low-pressure chemical vapor deposition method that allowed h-BN to be grown over a wide area (8 × 25 mm(2)). An electrochemical bubbling-based method was used to transfer the grown h-BN layer from the Pt foil onto an arbitrary substrate. This allowed t

With the exploding interest in transition metal chalcogenides, sulfide minerals containing the dianion S2(2-), such as pyrite (FeS2), cattierite (CoS2), and vaesite (NiS2), have recently attracted much attention for potential applications in energy conversion and storage devices. However, the synthesis of the patronite structure (VS4, V(4+)(S2(2-))2) and its applications have not yet been clearly demonstrated because of experimental difficulties and the existence of nonstoichiometric phases. Her

We developed a simple, versatile method of integrating hybrid thin films of reduced graphene oxide (RGO) nanosheets with multiwalled carbon nanotubes (MWNTs) via LbL assembly. This approach involves the electrostatic interactions of two oppositely charged suspensions of the RGO nanosheet with MWNTs. This method affords a hybrid multilayer of graphenes with excellent control over the optical and electrical properties. Moreover, the hybrid multilayer exhibits a significant increase of electronic c

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 MoSe 2 /WSe 2 vdW HSs based on photoluminescence (PL) and vdW-corrected density functional theory calculations. The PL intensity of the interlayer excitons depends primarily on the twist angle: It is enhanced at coherently stacked angles of 0° and

Hydrogen is considered to be a crucial clean energy for the future. As alternatives to Pt for the catalysis of the H2 evolution reaction (HER), transition metal dichalcogenides (TMDs) have shown great promise. In particular, significant new developments involving 2D layered TMDs have been recently reported. This highlight focuses on recent advances in the synthesis of 2D MoS2 and WS2 sheets, and their performance in the catalysis of the HER.

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 multilayer hexagonal boron nitride on a sapphire substrate by using high-temperature and low-pressure chemical vapor deposition. Microscopic and spectroscopic investigations and theoretical calculations reveal that synthesized hexagonal boron nitride has a single rotational orientation with AA' stacking

Poly(dopamine)-treated graphene oxide/poly(vinyl alcohol) ("dG-O/PVA") composite films were made and characterized. G-O was modified with poly(dopamine) in aqueous solution and then chemically reduced to yield poly(dopamine)-treated reduced G-O. A combination of hydrogen bonding, strong adhesion of poly(dopamine) at the interface of PVA and G-O sheets, and reinforcement by G-O resulted in increases in tensile modulus, ultimate tensile strength, and strain-to-failure by 39, 100, and 89%, respecti

A new approach for the fabrication of reduced graphene oxide (rGO) multilayers which can be used for transparent and conducting thin films was developed. This was achieved by using layer-by-layer (LbL) assembly of positively and negatively charged rGO sheets, which could provide highly controllable thin films in terms of thickness, transmittance, and sheet resistance. In particular, the thickness of the multilayer thin films of rGO was able to be controlled precisely in the subnanometre scale by