Universität zu Köln

Wang, Mengjing ORCID: 0000-0003-1195-4515, Kim, Jung Han, Han, Sang Sub, Je, Minyeong, Gil, Jaeyoung, Noh, Chanwoo, Ko, Tae-Jun, Lee, Kyu Seung, Son, Dong Ick, Bae, Tae-Sung, Ryu, Hyeon Ih, Oh, Kyu Hwan, Jung, YounJoon, Choi, Heechae ORCID: 0000-0002-9390-6607, Chung, Hee-Suk and Jung, Yeonwoong (2019). Structural Evolutions of Vertically Aligned Two-Dimensional MoS2 Layers Revealed by in Situ Heating Transmission Electron Microscopy. J. Phys. Chem. C, 123 (45). S. 27843 - 27854. WASHINGTON: AMER CHEMICAL SOC. ISSN 1932-7455

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Abstract

Benefiting from a large density of layer edges exposed on the surface, vertically aligned two-dimensional (2D) molybdenum disulfide (MoS2) layers have recently harvested excellent performances in the field of electrochemical catalysis and chemical sensing. With their increasing versatility for high-temperature, demanding applications, it is vital to identify their thermally driven structural and chemical stability, as well as to clarify its underlying principle. Despite various ex situ and in situ characterizations on horizontally aligned 2D MoS2 layers, the direct in situ heating of vertically aligned 2D MoS2 layers and the real-time observation of their near-atomic-scale dynamics have never been approached, leaving their thermal stability poorly understood. Moreover, the geometrical advantage of the surface-exposed vertically aligned 2D MoS2 layers is anticipated to unveil the structural dynamics of interlayer van der Waals (vdW) gaps and its correlation with thermal energy, unattainable with 2D MoS2 layers in any other geometry. Herein, we report a comprehensive in situ heating TEM study on cleanly transferred, vertically aligned 2D MoS2 layers up to 1000 degrees C. Several striking phenomena were newly observed in the course of heating: (1) formation and propagation of voids between the domains of vertical 2D MoS2 layers with distinct grain orientations starting at similar to 875 degrees C; (2) subsequent decompositions of the 2D MoS2 layers accompanying a formation of Mo nanoparticles at similar to 950 degrees C, a temperature much lower than the melting temperature of their bulk counterpart; and (3) initiation of decomposition from the surface-exposed 2D layer vertical edge sites, congruently supported by molecular dynamics (MD) simulation. These new findings will offer critical insights into better understanding the thermodynamic principle that governs the structural stability of general vdW 2D crystals as well as providing useful technological guidance for materials design and optimization in their potential high-temperature applications.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Wang, Mengjing UNSPECIFIED orcid.org/0000-0003-1195-4515 UNSPECIFIED Kim, Jung Han UNSPECIFIED UNSPECIFIED UNSPECIFIED Han, Sang Sub UNSPECIFIED UNSPECIFIED UNSPECIFIED Je, Minyeong UNSPECIFIED UNSPECIFIED UNSPECIFIED Gil, Jaeyoung UNSPECIFIED UNSPECIFIED UNSPECIFIED Noh, Chanwoo UNSPECIFIED UNSPECIFIED UNSPECIFIED Ko, Tae-Jun UNSPECIFIED UNSPECIFIED UNSPECIFIED Lee, Kyu Seung UNSPECIFIED UNSPECIFIED UNSPECIFIED Son, Dong Ick UNSPECIFIED UNSPECIFIED UNSPECIFIED Bae, Tae-Sung UNSPECIFIED UNSPECIFIED UNSPECIFIED Ryu, Hyeon Ih UNSPECIFIED UNSPECIFIED UNSPECIFIED Oh, Kyu Hwan UNSPECIFIED UNSPECIFIED UNSPECIFIED Jung, YounJoon UNSPECIFIED UNSPECIFIED UNSPECIFIED Choi, Heechae UNSPECIFIED orcid.org/0000-0002-9390-6607 UNSPECIFIED Chung, Hee-Suk UNSPECIFIED UNSPECIFIED UNSPECIFIED Jung, Yeonwoong UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-127628
DOI:	10.1021/acs.jpcc.9b06899
Journal or Publication Title:	J. Phys. Chem. C
Volume:	123
Number:	45
Page Range:	S. 27843 - 27854
Date:	2019
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	1932-7455
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language GENERALIZED GRADIENT APPROXIMATION; MONOLAYER MOS2; MELTING-POINT; SIZE; NANOSTRUCTURES; TRANSITION; REDUCTION; GROWTH; TEM Multiple languages Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/12762