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Publications

Prof. Zonghoon Lee’s Atomic-Scale Electron Microscopy Lab

Publications

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Publications in Nature | Science | their sister journals


Nature, 596, 519-524, 2021 Nature, 582, 511-514, 2020 / Nature Nanotechnology, 15, 289-295, 2020 / Nature Nanotechnology, 15, 59-66, 2020 / Science Advances, 6 (10), eaay4958, 2020 / Nature Electronics, 3, 207-215, 2020 / Nature Communications, 11 (1437), 2020 / Nature Energy, 3, 773-782, 2018 / Nature Communications, 8:1549, 2017 / Nature Communications, 6:8294, 2015 / Nature Communications, 6:7817, 2015 / Nature Communications, 5:3383, 2014




Abstract

 Preparation of edge-rich two-dimensional (2D) transition metal dichalocogenides (TMDs) has been actively investigated with the aim to improve their electrical and catalytic properties. Here, we elucidate the role of potassium ions in oxidation of TMDs and suggest a consequent novel anisotropic etching mechanism driven by self-running oxide droplets. We discover that potassium-mediated oxidation of MoS2 leads to the formation of K-intercalated hexagonal-phase molybdenum oxides (h-KxMoO3), whereas orthorhombic-phase oxides are formed in the absence of potassium ions. Metastable h-KxMoO3 appears to have decomposed into oxide droplets at higher temperature. Self-running of the oxide droplets leads to layer-by-layer anisotropic etching of MoS2 along the armchair direction. The motion of the droplets appears to be triggered by the surface energy instability between the oxide droplets and the underlying MoS2 layer. This study opens new possibilities to design and manufacture novel edge-rich 2D TMDs that do not follow the equilibrium Wulff shape by modulating their oxidation with the assistance of alkali metals and also offers fundamental insights into the interactions between nanodroplets and 2D materials toward edge engineering. 

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2011

Prior to Joining UNIST, 2011

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