Preferential Pt nanocluster seeding at grain boundary dislocations in polycrystalline monolayer MoS2

Journal article

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 anti-phase boundaries (i.e. 60o). 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, 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. DFT calculations confirm the energetic advantage of trapping Pt at dislocations on both the APB 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.

Authors: Wang, S; Sawada, H; Han, X; Zhou, S; Li, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: ACS Nano
• Volume: 12
• Issue: 6
• Pages: 5626-5636
• Publication date: 2018-05-15
• Acceptance date: 2018-05-08
• DOI: 10.1021/acsnano.8b01418
• EISSN: 1936-086X
• ISSN: 1936-0851
• Pmid: 29762015
• Language: English
• Keywords: MoS2; Pt dopants; density functional theory; 2D materials; ADF-STEM; grain boundary