Electronic structures, magnetic properties and band alignments of 3d transition metal atoms doped monolayer MoS2

Wu, Maokun; Yao, Xiaolong; Yuan, Hao; Dong, Hong; Cheng, Yahui; Liu, Hui; Lu, Feng; Wang, Weichao; Cho, Kyeongjae; Wang, Weihua

doi:10.1016/j.physleta.2017.10.024

Cited by 61 publications

(31 citation statements)

References 36 publications

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“…34 Notably, the Hubbard U correction was not added here since little changes were found for the electronic structure of MoS 2 in previous studies. [35][36][37][38] Material and membrane characterization. MoS 2 nanosheets were characterized through transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS).…”

Section: Methodsmentioning

confidence: 99%

Superselective Removal of Lead from Water by Two-Dimensional MoS₂ Nanosheets and Layer-Stacked Membranes

Wang

Sim

et al. 2020

Environ. Sci. Technol.

118

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Point-of-use (POU) devices with satisfactory lead (Pb 2+ ) removal performance are urgently needed in response to recent outbreaks of lead contamination in drinking water. This study experimentally demonstrated the excellent lead removal capability of two-dimensional (2D) MoS 2 nanosheets in aqueous form and as part of a layer-stacked membrane. Among all materials ever reported in the literature, MoS 2 nanosheets exhibit the highest adsorption capacity (740 mg/g), and the strongest selectivity/affinity towards Pb 2+ with a distribution coefficient K d that is orders of magnitude higher than that of other lead adsorption materials (5.2×10 7 mL/g). Density functional theory (DFT) simulation was performed to complement experimental measurements and to help understand the adsorption mechanisms. The results confirmed that the cation selectivity of MoS 2 follows the order Pb 2+ > Cu 2+ >> Cd 2+ > Zn 2+ , Ni 2+ > Mg 2+ , K + , Ca 2+ . The membrane formed with layer-stacked MoS 2 nanosheets exhibited a high water flux (145 L/ m 2 /h/bar), while effectively decreasing Pb 2+ concentration in drinking water from a few mg/L to less than 10 μg/L. The removal capacity of the MoS 2 membrane is a few orders of magnitude higher than that of other literature-reported membrane filters. Therefore, the layer-stacked MoS 2 membrane has great potential for POU removal of lead from drinking water.

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Section: Methodsmentioning

confidence: 99%

Superselective Removal of Lead from Water by Two-Dimensional MoS₂ Nanosheets and Layer-Stacked Membranes

Wang

Sim

et al. 2020

Environ. Sci. Technol.

118

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“…The calculations were spin-polarised and no symmetry constraints were imposed. The calculations implemented an on-site Hubbard correction (DFT+U) [48,49] to describe the partially filled Ti 3d and Mo 4d states; U=4.5 eV is applied to Ti 3d states and U=4.0 eV is applied to Mo 4d with these choices for U informed by previous studies [50][51][52][53][54].…”

Section: Dft Calculationsmentioning

confidence: 99%

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

et al. 2020

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This work outlines an experimental and theoretical investigation of the effect of molybdenum (Mo) doping on the oxygen vacancy formation and photocatalytic activity of TiO 2 . Analytical techniques such as x-ray diffraction (XRD), Raman, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to probe the anatase to rutile transition (ART), surface features and optical characteristics of Mo doped TiO 2 (Mo-TiO 2 ). XRD results showed that the ART was effectively impeded by 2 mol% Mo doping up to 750°C, producing 67% anatase and 33% rutile. Moreover, the crystal growth of TiO 2 was affected by Mo doping via its interaction with oxygen vacancies and the Ti-O bond. The formation of Ti-O-Mo and Mo-Ti-O bonds were confirmed by XPS results. Phonon confinement, lattice strain and non-stoichiometric defects were validated through the Raman analysis. DFT results showed that, after substitutional doping of Mo at a Ti site in anatase, the Mo oxidation state is Mo 6+ and empty Mo-s states emerge at the titania conduction band minimum. The empty Mo-d states overlap the anatase conduction band in the DOS plot. A large energy cost, comparable to that computed for pristine anatase, is required to reduce Mo-TiO 2 through oxygen vacancy formation. Mo 5+ and Ti 3+ are present after the oxygen vacancy formation and occupied states due to these reduced cations emerge in the energy gap of the titania host. PL studies revealed that the electron-hole recombination process in Mo-TiO 2 was exceptionally lower than that of TiO 2 anatase and rutile. This was ascribed to introduction of 5s gap states below the CB of TiO 2 by the Mo dopant. Moreover, the photo-generated charge carriers could easily be trapped and localised on the TiO 2 surface by Mo 6+ and Mo 5+ ions to improve the photocatalytic activity. coatings [8,9]. The most commonly existing crystalline polymorphs of TiO 2 are anatase, rutile and brookite [10][11][12]. Anatase is accepted to be the more active phase of TiO 2 and is preferred by the ceramic industries to fabricate light active antimicrobial indoor building materials such as ceramics, glass, tiles and sanitary surfaces [13,14]. This requires thermal stability of the anatase phase under typical ceramic processing conditions. TiO 2 anatase is mainly fabricated at low calcination temperatures (∼500°C) to prevent the anatase to rutile phase transition (ART) [15][16][17], which produces the less photo-active rutile phase. The photo-activity of anatase arises from its appropriate band edge positions, electron affinity, ionisation potential, and the long lifetime of charge carriers [10,12,18]. Moreover, transient photo-conductance analysis has revealed that the electron-hole recombination phenomena in anatase (101) phase is much slower compared to rutile (110), which is credited in part to the indirect band gap of anatase [11,19].The unit cells of anatase and rutile phases are composed of TiO 6 octahedra with titanium atoms at the centre and oxygen atoms at the vertices [20]. Both anatase and rutile have a t...

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“…All the first‐principles DFT calculations were performed using the generalized gradient approximation [ 32 ] with an on‐site Hubbard U ( U = 4.0 eV for Mo‐4d and U = 7.5 eV for Nd‐4f) [ 33 ] as implemented in the VASP package. [ 34 ] The cutoff energy for plane wave basis sets was 400 eV.…”

Section: Methodsmentioning

confidence: 99%

Defects Engineering Induced Ultrahigh Magnetization in Rare Earth Element Nd‐doped MoS₂

et al. 2020

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Various concentrations (0, 0.5, 1, and 5 at%) of Nd are doped into MoS2 single crystals via ion implantation. Experimental results reveal that Nd exists in the form of trivalent state when the doping concentration is below 5 at% and a variety of defects, such as sulfur and molybdenum vacancies, are formed in Nd‐doped MoS2. Compared to pure MoS2 that only shows diamagnetism, Nd doping successfully induces room‐temperature ferromagnetic ordering. Extremely high magnetization (1640 emu cm−3) is observed in 1 at% Nd‐doped MoS2. First‐principles density functional theory calculations suggest that the various structural defects, including substitutions, vacancies, interstitials, antisites, and their complexes, are magnetic possessing large spin moments. The defects coupled with Nd dopants ferromagnetically may form the bound magnetic polarons to induce ferromagnetic ordering. The work has demonstrated that through defects engineering and rare earth element doping, extremely high magnetization materials can be achieved in layered structured materials. On the other hand, though the experiment work is done by implanting MoS2 single crystals, theoretical calculations indicate that 2D MoS2 with bilayers or a few layers can also result in ultrahigh magnetization.

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Electronic structures, magnetic properties and band alignments of 3d transition metal atoms doped monolayer MoS2

Cited by 61 publications

References 36 publications

Superselective Removal of Lead from Water by Two-Dimensional MoS₂ Nanosheets and Layer-Stacked Membranes

Superselective Removal of Lead from Water by Two-Dimensional MoS₂ Nanosheets and Layer-Stacked Membranes

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Defects Engineering Induced Ultrahigh Magnetization in Rare Earth Element Nd‐doped MoS₂

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Electronic structures, magnetic properties and band alignments of 3d transition metal atoms doped monolayer MoS2

Cited by 61 publications

References 36 publications

Superselective Removal of Lead from Water by Two-Dimensional MoS2 Nanosheets and Layer-Stacked Membranes

Superselective Removal of Lead from Water by Two-Dimensional MoS2 Nanosheets and Layer-Stacked Membranes

Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Defects Engineering Induced Ultrahigh Magnetization in Rare Earth Element Nd‐doped MoS2

Contact Info

Product

Resources

About

Superselective Removal of Lead from Water by Two-Dimensional MoS₂ Nanosheets and Layer-Stacked Membranes

Superselective Removal of Lead from Water by Two-Dimensional MoS₂ Nanosheets and Layer-Stacked Membranes

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Defects Engineering Induced Ultrahigh Magnetization in Rare Earth Element Nd‐doped MoS₂