Ik Seon Kwon

Two-dimensional MoSe₂ has emerged as a promising electrocatalyst for the hydrogen evolution reaction (HER), although its catalytic activity needs to be further improved. Herein, we report Se-rich MoSe₂ nanosheets synthesized using a hydrothermal reaction, displaying much enhanced HER performance at the Se/Mo ratio of 2.3. The transition from the 2H to the 1T' phase occurred as Se/Mo exceeded 2. Structural analysis revealed the presence of Se adatoms as well as the formation

2D MoS₂ nanostructures have recently attracted considerable attention because of their outstanding electrocatalytic properties. The synthesis of unique Co-Ru-MoS₂ hybrid nanosheets with excellent catalytic activity toward overall water splitting in alkaline solution is reported. 1T' phase MoS₂ nanosheets are doped homogeneously with Co atoms and decorated with Ru nanoparticles. The catalytic performance of hydrogen evolution reaction (HER) and oxygen evolution re

Two-dimensional Re dichalcogenide nanostructures are promising electrocatalysts for the hydrogen evolution reaction (HER). Herein, we report the adatom doping of various transition metals (TM = Mn, Fe, Co, Ni, and Cu) in ReSe₂ nanosheets synthesized using a solvothermal reaction. As the atomic number of TM increases from Mn to Cu, the adatoms on Re sites become more favored over the substitution. In the case of Ni, the fraction of adatoms reaches 90%. Ni doping resulted in the most ef

Earth-abundant transition metal dichalcogenide nanosheets have emerged as an excellent catalyst for electrochemical water splitting to generate H₂. Alloying the nanosheets with heteroatoms is a promising strategy to enhance their catalytic performance. Herein, we synthesized hexagonal (2H) phase Mo_1-<i>x</i>Nb_<i>x</i>Se₂ nanosheets over the whole composition range using a solvothermal reaction. Alloying results in a variety of atomic-scale crystal defe

Alloying of transition metal dichalcogenides (TMDs) is a pioneering method for engineering electronic structures with expanded applications. In this study, MoSe₂ -VSe₂ -NbSe₂ ternary alloy nanosheets are synthesized via a colloidal reaction. The composition is successfully tuned over a wide range to adjust the 2H-1T phase transition. The alloy nanosheets consist of miscible atomic structures at all compositions, which is distinct from immiscible binary alloys. Co

Alloys of transition-metal dichalcogenide can display distinctive phase evolution because of their two-dimensional structures. Herein, we report the colloidal synthesis of Mo1–xVxSe2 alloy nanosheets with full composition tuning. Alloying led to a phase transition at x = 0.7 from the semiconducting 2H phase MoSe2 to the metallic 1T phase VSe2. It also produced significant V and Se vacancies, which became the richest in the 2H phase at x = 0.3–0.5. Extensive spin-polarized density functional theo

It is challenging to control the electronic structure of 2D transition metal dichalcogenides (TMD) for extended applications in renewable energy devices. Here, ReSe₂-VSe₂ (Re_1- _xV_xSe₂) alloy nanosheets over the whole composition range via a colloidal reaction is synthesized. Increasing x makes the nanosheets more metallic and induces a 1T″-to-1T phase transition at x = 0.5-0.6. Compared to the MoSe₂-VSe₂ and

Ternary alloying of transition metal dichalcogenides (TMDs) has the potential for altering the electronic structure of materials to suit electrochemical applications. Herein, we synthesized (MoWV)Se₂ nanosheets at various compositions <i>via</i> a colloidal reaction. The mole fraction of V atoms (<i>x</i>_V) was successfully increased up to 0.8, producing a metallic phase that is highly durable against hydration. Furthermore, we synthesized (MoW)Se₂ nanosheets ove

Tuning the electronic structures of transition metal dichalcogenides (TMD) is essential for their implementation in next-generation energy technologies. In this study, we synthesized composition-tuned WSe₂-VSe₂ (W_1-<i>x</i>V_<i>x</i>Se₂, <i>x</i> = 0-1) alloyed nanosheets using a colloidal reaction. Alloying the semiconducting WSe₂ with VSe₂ converts the material into a metallic one, followed by a 2H-to-1T phase transiti

The phase control of transition metal dichalcogenides (TMDs) is an intriguing approach for tuning the electronic structure toward extensive applications. In this study, WSe₂ nanosheets synthesized via a colloidal reaction exhibit a phase conversion from semiconducting 2H to metallic 2M under Se-rich growth conditions (i.e., increasing the concentration of Se precursor or lowering the growth temperature). High-resolution scanning transmission electron microscopy images are used to iden

Abstract Modulating the electronic structure of transition metal dichalcogenides (TMDs) via alloying is challenging despite the additional potential applications. In this study, a solvothermal reaction is used to synthesize composition‐tuned ReS 2 –VS 2 (Re 1‐ x V x S 2 ) alloy nanosheets featuring an expanded interlayer distance. Increasing x induces a phase transition from the semiconducting 1T″ phase ReS 2 to the metallic 3R‐stacking 1T phase VS 2 . Alloying via homogeneous atomic mixing rend

Abstract The novel two‐dimensional nanostructures of transition metal dichalcogenides (TMDs) have motivated extensive studies on the control of electronic structures via sandwiching of foreign species. Herein, we review our recent works on TMD nanosheets that intercalated with various molecules (i.e., amine, cobaltocene, porphyrin, phthalocyanine, etc.). They were mainly synthesized by a one‐step solvothermal reaction. The intercalation expanded the interlayer spacing significantly and induced t

The CO 2 hydrogenation reaction is a promising route for mitigating greenhouse gas emissions by converting CO 2 into value-added carbon monoxide through the reverse water–gas shift (RWGS) process. In this study, a surfactant-assisted mechanochemical synthesis was developed to prepare highly dispersed Cu catalysts supported on MgCeO x for the RWGS reaction. The combined use of CTAB (Hexadecyltrimethylammonium bromide, C 19 H 42 BrN) and Span®60 (Sorbitan monostearate, C 24 H 46 O 6 ) enabled simu