Properties of Individual Dopant Atoms in Single‐Layer MoS<sub>2</sub>: Atomic Structure, Migration, and Enhanced Reactivity

Lin, Yung‐Chang; Dumcenco, Dumitru; Komsa, Hannu‐Pekka; Niimi, Yasuhiro; Krasheninnikov, Arkady V.; Huang, Ying‐Sheng; Suenaga, Kazu

doi:10.1002/adma.201304985

Cited by 268 publications

(244 citation statements)

References 36 publications

(48 reference statements)

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“…19 Au atoms on the surface of MoS 2 have been observed on a range of atomic sites, such as on top of S, Mo, and hollow sites. 19 Recent work using ADF-STEM and EELS has further revealed that Cr and V dopants are often present in chemical vapor deposition (CVD)-grown MoS 2 , where the Cr/V dopants directly substitute Mo atoms. 20,21 The surface of 2D materials such as graphene and MoS 2 typically contains patches of amorphous carbon, and this modifies the local surface chemistry.…”

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confidence: 99%

Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS₂

et al. 2017

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We have studied atomic level interactions between single Pt atoms and the surface of monolayer MoS 2 using aberration-corrected annular dark field scanning transmission electron microscopy at an accelerating voltage of 60 kV. Strong contrast from single Pt atoms on the atomically resolved monolayer MoS 2 lattice enables their exact position to be determined with respect to the MoS 2 lattice, revealing stable binding sites. In regions of MoS 2 free from surface contamination, the Pt atoms are localized in S vacancy sites and exhibit dynamic hopping to nearby vacancy sites driven by the energy supplied by the electron beam. However, in areas of MoS 2 contaminated with carbon surface layers, the Pt atoms appear at various positions with respect to the underlying MoS 2 lattice, including on top of Mo and in off-axis positions. These variations are due to the Pt bonding with the surrounding amorphous carbon layer, which disrupts the intrinsic Pt−MoS 2 interactions, leading to more varied positions. Density functional theory (DFT) calculations reveal that Pt atoms on the surface of MoS 2 have a small barrier for migration and are stabilized when bound to either a single or double sulfur vacancies. DFT calculations have been used to understand how the catalytic activity of the MoS 2 basal plane for hydrogen evolution reaction is influenced by Pt dopants by variation of the hydrogen adsorption free energy. This strong dependence of catalytic effect on interfacial configurations is shown to be common for a series of dopants, which may provide a means to create and optimize reaction centers. KEYWORDS: Pt dopants, MoS 2 , ADF-STEM, 2D materials, catalysts, dopants T he presence of single isolated atom impurities and dopants either on the surface or directly bonded within the lattice structure of 2D materials influences the properties.1−10 Understanding the atomic structure that defines the bonding between single foreign atoms and the host 2D crystal is critical for developing accurate models that can predict the impacts of doping. Single metal atom doping of materials has also found significant recent interest in the development of catalysts by reducing the mass content of precious metals such as Pt, while maintaining high performance.11−13 A key aspect to single metal atom catalysts is preventing aggregation of the active species into clusters, reducing the loss of metal atoms by detachment, and providing the optimum bonding configuration for catalytic activity. Recent work has shown that doping 2D layered MoS 2 can lead to higher activities in the hydrogen evolution reaction, utilizing Co, Ni, and Pt single-metal dopants.14,15 MoS 2 is normally active only at edge sites, but the incorporation of isolated metal substitutional or surface dopants can activate the basal plane and lead to a large increase in the number of active catalytic sites. Therefore, resolving the atomic structure of single metal atoms and their structural interaction with MoS 2 helps reveal the stable configurations that dictate the catalytic...

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Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS₂

et al. 2017

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“…However, the details of such defect sites are still unclear, and PL can generally be observed only at low temperature. These issues may be resolved by the controlled fabrication of defect states, which is an important challenge in understanding and using TMDC atomic layers as quantum light sources.In general, defect states in low-dimensional materials are created through several mechanisms, including atomic vacancy formation, 12) impurity doping, [13][14][15][16] and chemical functionalization. 17) In this study, we have investigated impuritydoped WS 2 monolayers as a model system.…”

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“…These results are similar WS 2 growth by halide-assisted CVD reported previously. 21) For structural characterization, we conducted annular dark field (ADF)-STEM observations of a monolayer sample 13,14,23) It should be noted that the STEM images of the doped samples are different from those of pure WS 2 monolayers as observed previously. 14) Through a statistical analysis of the ADF-STEM images obtained at six different positions of the same grain, the ratio of dark spots is estimated to be 0.55 ± 0.03%.…”

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Growth and optical properties of Nb-doped WS₂ monolayers

Sasaki

Kobayashi

Liu³

et al. 2016

Appl. Phys. Express

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We report the chemical vapor deposition growth of Nb-doped WS 2 monolayers and their characterization. Electron microscopy observations reveal that the Nb atom was substituted at the W site at a rate of approximately 0.5%. Unlike Mo doping, Nb-doped samples have photoluminescence (PL) peaks at 1.4-1.6 eV at room temperature. The peak energies are lower than the optical bandgap of 1.8 eV, and a saturation behavior of PL intensity is observed with the increase in excitation power. These results indicate that the observed PL peaks are assignable to the emission from impurity states generated by the substitution of Nb. © 2016 The Japan Society of Applied Physics T he optical properties of atomic-layer transition metal dichalcogenides (TMDCs) have recently attracted much attention owing to their wide-range bandgap energies from visible to infrared, 1-3) unique phenomena related to spin-valley physics, 4,5) and single-photon emission. [6][7][8][9] In particular, defect-derived excitonic states have recently received much attention for their applications in single-photon emitters. To date, several groups have reported that atomic-layer TMDCs show photoluminescence (PL) from optically active defects at low temperature (4 ∼ 90 K). 6-11) Such a two-dimensional (2D) single-quantum emission has practical advantages in efficient photon extraction and high integration capability. However, the details of such defect sites are still unclear, and PL can generally be observed only at low temperature. These issues may be resolved by the controlled fabrication of defect states, which is an important challenge in understanding and using TMDC atomic layers as quantum light sources.In general, defect states in low-dimensional materials are created through several mechanisms, including atomic vacancy formation, 12) impurity doping, [13][14][15][16] and chemical functionalization. 17) In this study, we have investigated impuritydoped WS 2 monolayers as a model system. Monolayer WS 2 is a semiconductor with a relatively wide direct bandgap and high air stability, and there have been many reports on its growth process and characterization. 10,[18][19][20][21][22] To implant impurities in WS 2 , we employed halide-assisted chemical vapor deposition (CVD), which was recently developed by Li et al. 21) This method can produce large-area monolayer WS 2 at relatively low temperatures (700°C) and under atmospheric pressure. Importantly, the use of halides can effectively transport precursors of transition metals, which usually have very low vapor pressure. As an impurity, Mo atoms are well studied and cause bandgap narrowing through the substitution of W sites in monolayer WS 2 . 14,15,23,24) However, there are very few studies on the doping of other transition metals for monolayer TMDCs. In the present study, Nb is selected because its atomic size is comparable to that of Mo and it is reported to generate acceptor states for some TMDCs. 16,25) Here, we report the synthesis and characterization of monolayer impurity-doped WS 2 using halide-ass...

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“…Lin et al [66] have studied the localization sites and mobility of gold and rhenium metal atoms in the MoS 2 monolayer. The adatoms were shown to have a perturbation effect on the energy states of the adjacent matrix atoms and have elevated reactivity, i.e., may potentially act as catalytically-active sites.…”

Section: Doping Of 2d Mos 2 With Metal Atomsmentioning

confidence: 99%

Nanocomposites of Two-Dimensional Molybdenum and Tungsten Dichalcogenides with Metal Particles: Preparation and Prospects for Application

Lampeka

Tsymbal

2015

Theor Exp Chem

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Properties of Individual Dopant Atoms in Single‐Layer MoS₂: Atomic Structure, Migration, and Enhanced Reactivity

Cited by 268 publications

References 36 publications

Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS₂

Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS₂

Growth and optical properties of Nb-doped WS₂ monolayers

Nanocomposites of Two-Dimensional Molybdenum and Tungsten Dichalcogenides with Metal Particles: Preparation and Prospects for Application

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Properties of Individual Dopant Atoms in Single‐Layer MoS2: Atomic Structure, Migration, and Enhanced Reactivity

Cited by 268 publications

References 36 publications

Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS2

Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS2

Growth and optical properties of Nb-doped WS2 monolayers

Nanocomposites of Two-Dimensional Molybdenum and Tungsten Dichalcogenides with Metal Particles: Preparation and Prospects for Application

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Product

Resources

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Properties of Individual Dopant Atoms in Single‐Layer MoS₂: Atomic Structure, Migration, and Enhanced Reactivity

Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS₂

Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS₂

Growth and optical properties of Nb-doped WS₂ monolayers