scholarly journals Structure and Stability of Cun Clusters (N = 1-4) Adsorbed on Stoichiometric and Defective 2D MoS2

2019 ◽  
Author(s):  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Density Functional ◽  
Noble Metals ◽  
Semiconductor Device ◽  
2D Materials ◽  
Single Atom ◽  
Copper Binding ◽  
Adsorption Sites ◽  
Mos2 Monolayer ◽  
Potential Applications ◽  
Low Dimensional

<div>Layered materials, such as MoS2, are being intensely studied due to their interesting properties and wide variety of potential applications. These materials are also interesting as supports for low dimensional metals for catalysis, while recent work has shown increased interest in using 2D materials in the electronics industry as a Cu diffusion barrier in semiconductor device interconnects. The interaction between different metal structures and MoS2 monolayers is therefore of significant importance and first principle simulations can probe aspects of this interaction not easily accessible to experiment. Previous theoretical studies have focused particularly on the adsorption of a range of metallic elements, including first row transition metals, as well as Ag and Au. However, most studies have examined single atom adsorption or adsorb nanoparticles of noble metals. This means there is a knowledge gap in terms of thin film nucleation on 2D materials. To begin addressing this issue, we present in this paper a first principles density functional theory (DFT) study of the adsorption of small Cu_n structures, where n = 1-4, on 2D MoS2 as a model system. We find on a perfect MoS2 monolayer that a single Cu atom prefers an adsorption site above the Mo atom. With increasing nanocluster size the nanocluster binds more strongly when Cu atoms adsorb atop the S atom. Stability is driven by the number of Cu-Cu interactions and the distance between adsorption sites, with no obvious preference towards 2D or 3D structures. The introduction of a single S vacancy in the monolayer enhances copper binding energy, although some Cu_n nanoclusters are actually unstable. The effect of the vacancy is localised around the vacancy site. Finally on both the pristine and defective MoS2 monolayer, the density of states analysis shows that the adsorption of Cu introduces new electronic states as a result of partial Cu oxidation, but the metallic character of Cu nanoclusters is preserved. </div><div><br></div>

scholarly journals Structure and Stability of Cun Clusters (N = 1-4) Adsorbed on Stoichiometric and Defective 2D MoS2

2019 ◽  
Author(s):  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Density Functional ◽  
Noble Metals ◽  
Semiconductor Device ◽  
2D Materials ◽  
Single Atom ◽  
Copper Binding ◽  
Adsorption Sites ◽  
Mos2 Monolayer ◽  
Potential Applications ◽  
Low Dimensional

<div>Layered materials, such as MoS2, are being intensely studied due to their interesting properties and wide variety of potential applications. These materials are also interesting as supports for low dimensional metals for catalysis, while recent work has shown increased interest in using 2D materials in the electronics industry as a Cu diffusion barrier in semiconductor device interconnects. The interaction between different metal structures and MoS2 monolayers is therefore of significant importance and first principle simulations can probe aspects of this interaction not easily accessible to experiment. Previous theoretical studies have focused particularly on the adsorption of a range of metallic elements, including first row transition metals, as well as Ag and Au. However, most studies have examined single atom adsorption or adsorb nanoparticles of noble metals. This means there is a knowledge gap in terms of thin film nucleation on 2D materials. To begin addressing this issue, we present in this paper a first principles density functional theory (DFT) study of the adsorption of small Cu_n structures, where n = 1-4, on 2D MoS2 as a model system. We find on a perfect MoS2 monolayer that a single Cu atom prefers an adsorption site above the Mo atom. With increasing nanocluster size the nanocluster binds more strongly when Cu atoms adsorb atop the S atom. Stability is driven by the number of Cu-Cu interactions and the distance between adsorption sites, with no obvious preference towards 2D or 3D structures. The introduction of a single S vacancy in the monolayer enhances copper binding energy, although some Cu_n nanoclusters are actually unstable. The effect of the vacancy is localised around the vacancy site. Finally on both the pristine and defective MoS2 monolayer, the density of states analysis shows that the adsorption of Cu introduces new electronic states as a result of partial Cu oxidation, but the metallic character of Cu nanoclusters is preserved. </div><div><br></div>

scholarly journals DFT calculations of the structure and stability of copper clusters on MoS2

2020 ◽  
Vol 11 ◽  
pp. 391-406
Author(s):  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Noble Metals ◽  
Semiconductor Device ◽  
2D Materials ◽  
Single Atom ◽  
Copper Binding ◽  
Adsorption Sites ◽  
Potential Applications ◽  
Low Dimensional

Layered materials, such as MoS2, are being intensely studied due to their interesting properties and wide variety of potential applications. These materials are also interesting as supports for low-dimensional metals for catalysis, while recent work has shown increased interest in using 2D materials in the electronics industry as a Cu diffusion barrier in semiconductor device interconnects. The interaction between different metal structures and MoS2 monolayers is therefore of significant importance and first-principles simulations can probe aspects of this interaction not easily accessible to experiment. Previous theoretical studies have focused particularly on the adsorption of a range of metallic elements, including first-row transition metals, as well as Ag and Au. However, most studies have examined single-atom adsorption or adsorbed nanoparticles of noble metals. This means there is a knowledge gap in terms of thin film nucleation on 2D materials. To begin addressing this issue, we present in this paper a first-principles density functional theory (DFT) study of the adsorption of small Cu n (n = 1–4) structures on 2D MoS2 as a model system. We find on a perfect MoS2 monolayer that a single Cu atom prefers an adsorption site above the Mo atom. With increasing nanocluster size the nanocluster binds more strongly when Cu atoms adsorb atop the S atoms. Stability is driven by the number of Cu–Cu interactions and the distance between adsorption sites, with no obvious preference towards 2D or 3D structures. The introduction of a single S vacancy in the monolayer enhances the copper binding energy, although some Cu n nanoclusters are actually unstable. The effect of the vacancy is localised around the vacancy site. Finally, on both the pristine and the defective MoS2 monolayer, the density-of-states analysis shows that the adsorption of Cu introduces new electronic states as a result of partial Cu oxidation, but the metallic character of Cu nanoclusters is preserved.

Hydrogenation as a source of superconductivity in two-dimensional TiB2

2021 ◽  
pp. 2150057
Author(s):  
Hui Wang ◽  
Chen Pan ◽  
Sheng-Yan Wang ◽  
Hong Jiang ◽  
Yin-Chang Zhao ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Vibration Frequency ◽  
First Principles ◽  
Density Functional ◽  
Tensile Strain ◽  
2D Materials ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Density Functional Perturbation Theory ◽  
Potential Applications

Using first-principles calculations based on density functional perturbation theory, we demonstrate hydrogenation-induced superconductivity in monolayer TiB2H. Hydrogen adatoms destroy the Dirac state of monolayer TiB2 and monolayer TiB2H has a high vibration frequency. Monolayer TiB2H is a phonon-mediated superconductor. Monolayer TiB2H has a predicted [Formula: see text] of 8[Formula: see text]K, which further increases under external tensile strain. Thus, this study extends our understanding of superconductivity in two-dimensional (2D) materials and its potential applications.

First-principles calculations on structure and electronic properties of α-zirconium hydrogen phosphate

MRS Advances ◽  
2019 ◽  
Vol 4 (50) ◽  
pp. 2699-2707
Author(s):  
V. W. Elloh ◽  
Soni Mishra ◽  
A. Yaya ◽  
Abhishek Kumar Mishra
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Semiconductor Device ◽  
Electronic Band Structure ◽  
Structural Parameters ◽  
Hydrogen Phosphate ◽  
Electronic Band ◽  
Potential Applications ◽  
Direct Band

AbstractLayered zirconium hydrogen phosphate intercalation compounds can be easily tuned, leading to potential applications in many fields, specifically by introducing them in different polymeric composites as nanofillers. Employing first-principles density functional theory based calculations, we have investigated ground state electronic structure properties of α-zirconium hydrogen phosphate (α-ZrP). We discuss the structure and electronic band structure, where projected density of states calculations have been discussed to understand the different atomic orbitals contributions to electronic bands. ZrP has numerous properties of interest for use in many semiconductor device structures, specifically, layered zirconium hydrogen phosphate has substantial promise for both optical devices and for high power electronics due to its large direct band gap. Our structural calculations suggest that layered zirconium hydrogen phosphate exhibits monoclinic structure. The calculated structural parameters and band gap are in good agreement with available experimental data.

scholarly journals Mott–Hubbard insulating state for the layered van der Waals $$\hbox {FePX}_3$$ (X: S, Se) as revealed by NEXAFS and resonant photoelectron spectroscopy

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Yichen Jin ◽  
Mouhui Yan ◽  
Tomislav Kremer ◽  
Elena Voloshina ◽  
Yuriy Dedkov
Keyword(s):  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
2D Materials ◽  
Van Der Waals ◽  
Deep Understanding ◽  
Density Functional Theory Calculations ◽  
Binding Energies ◽  
Final State ◽  
Spectroscopy Studies ◽  
Low Dimensional

AbstractA broad family of the nowadays studied low-dimensional systems, including 2D materials, demonstrate many fascinating properties, which however depend on the atomic composition as well as on the system dimensionality. Therefore, the studies of the electronic correlation effects in the new 2D materials is of paramount importance for the understanding of their transport, optical and catalytic properties. Here, by means of electron spectroscopy methods in combination with density functional theory calculations we investigate the electronic structure of a new layered van der Waals $$\hbox {FePX}_3$$ FePX 3 (X: S, Se) materials. Using systematic resonant photoelectron spectroscopy studies we observed strong resonant behavior for the peaks associated with the $$3d^{n-1}$$ 3 d n - 1 final state at low binding energies for these materials. Such observations clearly assign $$\hbox {FePX}_3$$ FePX 3 to the class of Mott–Hubbard type insulators for which the top of the valence band is formed by the hybrid Fe-S/Se electronic states. These observations are important for the deep understanding of this new class of materials and draw perspectives for their further applications in different application areas, like (opto)spintronics and catalysis.

scholarly journals Prediction of Co and Ru nanocluster morphology on 2D MoS2 from interaction energies

2021 ◽  
Vol 12 ◽  
pp. 704-724
Author(s):  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Thin Film ◽  
Density Functional ◽  
Semiconductor Device ◽  
Bulk Material ◽  
Metal Substrate ◽  
Single Atom ◽  
Sulfur Vacancy ◽  
Metal Interaction ◽  
Wide Range ◽  
Metal Metal

Layered materials, such as MoS2, have a wide range of potential applications due to the properties of a single layer, which often differ from the bulk material. They are of particular interest as ultrathin diffusion barriers in semiconductor device interconnects and as supports for low-dimensional metal catalysts. Understanding the interaction between metals and the MoS2 monolayer is of great importance when selecting systems for specific applications. In previous studies the focus has been largely on the strength of the interaction between a single atom or a nanoparticle of a range of metals, which has created a significant knowledge gap in understanding thin film nucleation on 2D materials. In this paper, we present a density functional theory (DFT) study of the adsorption of small Co and Ru structures, with up to four atoms, on a monolayer of MoS2. We explore how the metal–substrate and metal–metal interactions contribute to the stability of metal clusters on MoS2, and how these interactions change in the presence of a sulfur vacancy, to develop insight to allow for a prediction of thin film morphology. The strength of interaction between the metals and MoS2 is in the order Co > Ru. The competition between metal–substrate and metal–metal interaction allows us to conclude that 2D structures should be preferred for Co on MoS2, while Ru prefers 3D structures on MoS2. However, the presence of a sulfur vacancy decreases the metal–metal interaction, indicating that with controlled surface modification 2D Ru structures could be achieved. Based on this understanding, we propose Co on MoS2 as a suitable candidate for advanced interconnects, while Ru on MoS2 is more suited to catalysis applications.

scholarly journals In-situ Gas Adsorption SC-XRD Study: Understanding Gas Uptake in a Sc-based MOF

2014 ◽  
Vol 70 (a1) ◽  
pp. C1261-C1261
Author(s):  
Jorge Sotelo ◽  
Scott McKellar ◽  
Stephen Moggach ◽  
John Mowat ◽  
Anna Warren ◽  
...  
Keyword(s):  
Density Functional ◽  
Gas Adsorption ◽  
Density Functional Theory Calculations ◽  
Point Of View ◽  
Adsorption Sites ◽  
Potential Applications ◽  
Energetic Point ◽  
Desorption Mechanism ◽  
Adsorption Desorption

In recent years the development of new methods of storing, trapping or separating light gases, such as CO2, CH4 and CO has become of utmost importance from an environmental and energetic point of view. Porous materials such as zeolites and porous organic polymers have long been considered good candidates for this purpose. More recently, the ample spectrum of existing metal organic frameworks (MOFs) together with their functional and mechanical properties have attracted even further interest. The porous channels found in these materials are ideal for the uptake of guests of different shapes and sizes, and with careful design they can show high selectivity. Adsorption properties of MOFs have been thoroughly studied, however obtaining in depth structural insight into the adsorption/desorption mechanism of these materials is challenging. For example, out of the hundreds of MOF structures published to date, there are less than 20 entries currently in the CSD in which the CO2 molecule can be located. Here we present our novel findings using the high-pressure gas cell at the Diamond Light Source on beamline I19, where we have studied the inclusion of CO2, CH4 and CO on the microporous scandium framework, Sc2BDC3 (BDC = benzene-1,4-dicarboxylate) and its amino-functionalised derivative, Sc2(BDC-NH2)3. Here, the different adsorption sites for CO2, CH4 and CO in both frameworks have been determined as a function of increasing gas pressure. These structures, coupled with Density Functional Theory calculations, have helped to elucidate the host-guest interactions governing the different levels of selectivity shown by both Sc2BDC3 and Sc2(BDC-NH2)3. Additionally, gas mixtures have also been studied; in particular CO2/CH4 mixtures of different compositions, explaining the selectivity of the frameworks for CO2 over other gases and showing the great potential of in situ structural experiments for investigation of the potential applications of MOFs.

scholarly journals First Principles Study of Tritium Diffusion in Li2TiO3 Crystal with Lithium Vacancy

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2383 ◽  
Author(s):  
Kun Li ◽  
Wen Yang ◽  
Wei-Hua Wang ◽  
Yong-Tang Li
Keyword(s):  
Energy Barrier ◽  
Density Functional ◽  
Minimum Energy ◽  
Density Functional Theory Calculations ◽  
Release Process ◽  
Adsorption Sites ◽  
Tritium Atom ◽  
The Density Functional Theory ◽  
Potential Applications ◽  
Lithium Vacancy

Li2TiO3 is one of the most significant breeder materials and has potential applications in future fusion reactors. Defect models with three types of lithium vacancies were considered to study the diffusion behavior of tritium in Li2TiO3 by the density functional theory calculations. The possible tritium adsorption sites inside the lithium vacancy were examined and analyzed. The energy barrier of all diffusion paths between different adsorption sites was calculated and the minimum energy barrier is about 0.45 eV, which indicates that the tritium atom diffuses freely inside the lithium vacancy; when a tritium diffuses across the crystal in the typical three directions, our results reveal that the tritium atom prefers to move along the [010] direction. Furthermore, we found that the minimum energy barrier for the tritium atom to escape the trap of Li vacancy is 0.76 eV. After the tritium jumping out of the Li vacancy, the minimum energy barrier is 0.5 eV for the tritium atom diffusing in the crystal. Therefore, we predict that tritium can easily escape from the trap of the Li vacancy and then diffuse across the crystal. Such results are beneficial to the tritium release process in Li2TiO3 and could provide theoretical guidance for the future applications of the Li2TiO3 materials.

scholarly journals Tunable Single-Atomic Charge/Spin States of Intercalant Co Ions in a Transition Metal Dichalcogenide

2021 ◽  
Author(s):  
Seongjoon Lim ◽  
Shangke Pan ◽  
Kefeng Wang ◽  
Alexey Ushakov ◽  
Ekaterina Sukhanova ◽  
...  
Keyword(s):  
Transition Metal ◽  
Scanning Probe Microscopy ◽  
Density Functional ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Atomic Charge ◽  
Single Atom ◽  
Transition Metal Dichalcogenide ◽  
Functional Theory ◽  
Metal Dichalcogenides

Abstract Intercalation raises manifold possibilities to manipulate the properties of two-dimensional (2D) materials1, and its impact on local electronic/magnetic properties has drawn much attention with the rise of nano-structured 2D materials2,3. Typically, changing an ionic state in a solid involves a dramatic local change of energy as well as orbital/spin magnetic moment from its ground state. However, the atomic investigation of the charging process of an intercalant ion in 2D material has never been explored while such subject has been studied in artificially deposited atoms on thin insulating 2D layers using scanning probe microscopy4–7. Herein, we demonstrate an atomical manipulation of the charge and spin state of Co ions on a metallic NbS2, obtained by cleaving of Co-intercalated NbS2. Density functional theory investigation of various Co configurations reveals that the charging is possible due to a change in the crystal field at the surface and a significant coupling between NbS2 and intercalants occurs via orbitals of the a1g symmetry. The results can be generalized to numerous other combinations of intercalants and base matrixes, suggesting that intercalated transition metal dichalcogenides can be a new platform to introduce single-atom operation 2D electronics/spintronics.

scholarly journals Flexoelectric and Piezoelectric Coupling in a Bended MoS2 Monolayer

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2086
Author(s):  
Hanna V. Shevliakova ◽  
Semen O. Yesylevskyy ◽  
Ihor Kupchak ◽  
Galina I. Dovbeshko ◽  
Yunseok Kim ◽  
...  
Keyword(s):  
Flexible Electronics ◽  
Strain Gradient ◽  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Strain Engineering ◽  
Mos2 Monolayer ◽  
Shear Component ◽  
Order Of Magnitude ◽  
Metal Dichalcogenides ◽  
Low Dimensional

Low-dimensional (LD) transition metal dichalcogenides (TMDs) in the form of nanoflakes, which consist of one or several layers, are the subject of intensive fundamental and applied research. The tuning of the electronic properties of the LD-TMDs are commonly related with applied strains and strain gradients, which can strongly affect their polar properties via piezoelectric and flexoelectric couplings. Using the density functional theory and phenomenological Landau approach, we studied the bended 2H-MoS2 monolayer and analyzed its flexoelectric and piezoelectric properties. The dependences of the dipole moment, strain, and strain gradient on the coordinate along the layer were calculated. From these dependences, the components of the flexoelectric and piezoelectric tensors have been determined and analyzed. Our results revealed that the contribution of the flexoelectric effect dominates over the piezoelectric effect in both in-plane and out-of-plane directions of the monolayer. In accordance with our calculations, a realistic strain gradient of about 1 nm−1 can induce an order of magnitude higher than the flexoelectric response in comparison with the piezoelectric reaction. The value of the dilatational flexoelectric coefficient is almost two times smaller than the shear component. It appeared that the components of effective flexoelectric and piezoelectric couplings can be described by parabolic dependences of the corrugation. Obtained results are useful for applications of LD-TMDs in strain engineering and flexible electronics.

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