Adsorption of gas molecules on monolayer MoS2 and effect of applied electric field

Qu, Yue; Shao, Zhenhai; Chang, Soon-Bok; Li, Jingbo

doi:10.1186/1556-276x-8-425

Cited by 643 publications

(540 citation statements)

References 42 publications

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“…Molecular adsorption plays an important role in many applications, such as catalysis [1][2][3], molecular sensing [4,5], photovoltaics [6,7], and chemical separation [8,9]. The adsorption process typically involves changes in the physical or chemical properties of the adsorbed molecule and the adsorbing surface.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

Darwish

Fadlallah

Badawi

et al. 2016

Applied Surface Science

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Molecular adsorption on surfaces is a key element for many applications, including sensing and catalysis. Non-invasive sugar sensing has been an active area of research due to its importance to diabetes care. The adsorption of sugars on a template surface study is at the heart of matter.Here, we study doped hexagonal boron nitride sheets (h-BNNs) as adsorbing and sensing template for glucose and glucosamine. Using first principles calculations, we find that the adsorption of glucose and glucosamine on h-BNNs is significantly enhanced by the substitutional doping of the sheet with Al and Ga. Including long range van der Waals corrections gives adsorption energies of about 2 eV. In addition to the charge transfer occurring between glucose and the Al/Ga-doped BN sheets, the adsorption alters the size of the band gap, allowing for optical detection of adsorption.We also find that Al-doped boron nitride sheet is better than Ga-nitride sheet to enhance the adsorption energy of glucose and glucosamine. The results of our work can be potentially utilized when designing support templates for glucose and glucosamine.

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Section: Introductionmentioning

confidence: 99%

Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

Darwish

Fadlallah

Badawi

et al. 2016

Applied Surface Science

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“…It has been reported in literature from photoluminescence measurements that physisorption of H 2 O and O 2 molecules leads to a reduction of the charge carrier density in MoS 2 [12,14].The physisorbed molecules act as molecular gates [12,15] [12,14]. These values are for defect free crystals.…”

mentioning

confidence: 96%

“…The impact of substrates [10,11], the gaseous environment as well as of adsorbates [12][13][14] on the optoelectronic properties of 2D materials have been reported. The atomistic interfaces offer the opportunity of novel route for interfacial engineering of electronic, optical and optoelectronic properties [10,12,15,16].…”

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confidence: 99%

Photogating of mono- and few-layer MoS2

Miller

Parzinger

Vernickel

et al. 2015

Applied Physics Letters

126

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We describe a photogating effect in mono-and few-layer MoS2, which allows the control of the charge carrier density by almost two orders of magnitude without electrical contacts. Our Raman studies are consistent with physisorbed environmental molecules, that effectively deplete the intrinsically n-doped charge carrier system via charge transfer, and which can be gradually removed by the exposure to light. This photogating process is reversible and precisely tunable by the light intensity. The photogating efficiency is quantified by comparison with measurements on electrostatically gated MoS2.Two-dimensional layered van-der Waals materials and their heterostructures, particularly the transition metal dichalcogenides (TMDCs) family such as MoS 2 , are of great interest for fundamental research as well as for novel device concepts in the areas of electronic [1,2], optoelectronic [1,[3][4][5], valley-and spintronic [6] as well as solar energy conversion [7] and sensing applications [8]. It has been demonstrated that MoS 2 undergoes a transition from an indirect to a direct bandgap semiconductor by thinning it down to one single layer [3]. The direct gap at the K-point with E gap = 1.9 eV [3] remains almost unaffected by the number of layers. The indirect gap existing in vicinity of the Γ-point decreases in energy for increasing number of layers [3]. In particular, a high absorption of the monolayer of 5-10% in the visible regime [9] makes MoS 2 a promising material for optoelectronic devices such as phototransistors and solar cells. For atomistic thin materials, knowledge about the interaction with the dielectric environment is of great importance. The impact of substrates [10,11], the gaseous environment as well as of adsorbates [12][13][14] on the optoelectronic properties of 2D materials have been reported. The atomistic interfaces offer the opportunity of novel route for interfacial engineering of electronic, optical and optoelectronic properties [10,12,15,16].In this letter, we study the effect of photogating in MoS 2 mono-and few-layer flakes by means of Raman spectroscopy. Our observations are consistent with physisorbed environmental molecules acting as molecular gates. The molecules can be gradually removed from the MoS 2 surface by the exposure to light. We find that the photogating effect facilitates the control of the charge carrier density in MoS 2 by almost two orders of magnitude in pristine flakes without the need for electrical contacts. In general, Raman spectroscopy provides access to various properties of 2D layered materials [17] such as to the number of layers [18,19], to strain [20,21] to the local temperature [22] and to the doping level [23]. The Raman spectrum of MoS 2 includes two prominent firstorder phonon modes, the E 1 2g and the A 1g mode [17]. The E 1 2g mode is an in-plane mode, i.e. the atoms are oscillating parallel to the basal plane of the van-der Waals coupled crystal layers. The A 1g mode is an out-of plane oscillation, where the sulfur atoms are moving in opposite directions...

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“…According to Ref. [19], STM observation of multiple high-coordination adsorption sites allows to identify these defects as adsorbed CO molecules. Intercalation by CO molecules can provide more robust boundary conditions for phonon interference, because of local binding between the islands and the substrate induced by their dipole moments.…”

Section: Methodsmentioning

confidence: 99%

Scanning Tunneling Microscopy of Atomic Scale Phonon Standing Waves in Quasi-freestanding WSe2 Monolayers

et al. 2016

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Using scanning tunneling microscopy (STM) we observed atomic scale interference patterns on quasi-freestanding WSe 2 islands grown on top of graphene. The bias-independent double atomic size periodicity of these patterns and the sharp Brillouin zone edge revealed by 2D STM Fourier analysis indicate formation of optical phonon standing waves due to scattering on intercalating defects supporting these islands. Standing wave patterns of both synchronized and non-synchronized optical phonons, corresponding to resonant and non-resonant phonon scattering regimes, were experimentally observed. We also found the symmetry breaking effect for individual phonon wave packets, one of the unique features distinguishing phonon standing waves. We show that vibrational and electronic anharmonicities are responsible for STM detection of these patterns. A significant contribution to the interference contrast arises from quantum zero-point oscillations.

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Adsorption of gas molecules on monolayer MoS2 and effect of applied electric field

Cited by 643 publications

References 42 publications

Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

Photogating of mono- and few-layer MoS2

Scanning Tunneling Microscopy of Atomic Scale Phonon Standing Waves in Quasi-freestanding WSe2 Monolayers

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