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Preferential Pt nanocluster seeding at grain boundary dislocations in polycrystalline monolayer MoS 2

DOI: 10.1021/acsnano.8b01418 DOI Help

Authors: Shanshan Wang (University of Oxford; National University of Defense Technology) , Hidetaka Sawada (JEOL Ltd) , Xiaoyuan Han (University College London) , Si Zhou (University of Oxford) , Sha Li (University of Oxford) , Zheng Xiao Guo (University College London) , Angus I. Kirkland (University of Oxford; Diamond Light Source) , Jamie H. Warner (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Nano

State: Published (Approved)
Published: May 2018

Abstract: We show that Pt nanoclusters preferentially nucleate along the grain boundaries (GBs) in polycrystalline MoS2 monolayer films, with dislocations acting as the seed site. Atomic resolution studies by aberration-corrected annular dark-field scanning transmission electron microscopy reveal periodic spacing of Pt nanoclusters with dependence on GB tilt angles and random spacings for the antiphase boundaries (i.e., 60°). Individual Pt atoms are imaged within the dislocation core sections of the GB region, with various positions observed, including both the substitutional sites of Mo and the hollow center of the octahedral ring. The evolution from single atoms or small few atom clusters to nanosized particles of Pt is examined at the atomic level to gain a deep understanding of the pathways of Pt seed nucleation and growth at the GB. Density functional theory calculations confirm the energetic advantage of trapping Pt at dislocations on both the antiphase boundary and the small-angle GB rather than on the pristine lattice. The selective decoration of GBs by Pt nanoparticles also has a beneficial use to easily identify GB areas during microscopic-scale observations and track long-range nanoscale variances of GBs with spatial detail not easy to achieve using other methods. We show that GBs have nanoscale meandering across micron-scale distances with no strong preference for specific lattice directions across macroscopic ranges.

Journal Keywords: 2D materials; ADF-STEM; density functional theory; grain boundary; MoS2; Pt dopants

Subject Areas: Materials, Chemistry

Diamond Offline Facilities: Electron Physical Sciences Imaging Centre (ePSIC)
Instruments: E02-JEM ARM 300CF

Added On: 22/05/2018 13:54

Discipline Tags:

Physical Chemistry Chemistry Materials Science Nanoscience/Nanotechnology

Technical Tags:

Microscopy Electron Microscopy (EM) Scanning Transmission Electron Microscopy (STEM)