scholarly journals Prediction of Co and Ru Nanocluster Morphology on 2D MoS2 from Interaction Energies

2021 ◽  
Author(s):  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Thin Film ◽  
Density Functional ◽  
Bulk Material ◽  
Single Layer ◽  
Metal Substrate ◽  
Single Atom ◽  
Metal Interaction ◽  
Wide Range ◽  
Metal Metal ◽  
Sulphur Vacancy

Layered materials, such as \ce{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 ultra-thin diffusion barriers in semi-conductor device interconnects and as supports for low dimensional metal catalysts. Understanding the interaction between metals and the \ce{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 \ce{MoS2}. We explore how the metal-substrate and metal-metal interactions contribute to the stability of metal clusters on \ce{MoS2}, and how these interactions change in the presence of a sulphur vacancy, to develop insight to allow prediction of thin film morphology. The strength of interaction between the metals and \ce{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 \ce{MoS2}, while Ru prefers 3D structures on \ce{MoS2}. However, the presence of a sulphur 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 \ce{MoS2} as a suitable candidate for advanced interconnects, while Ru on \ce{MoS2} is more suited to catalysis applications.

scholarly journals Prediction of Co and Ru Nanocluster Morphology on 2D MoS2 from Interaction Energies

2021 ◽  
Author(s):  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Thin Film ◽  
Density Functional ◽  
Bulk Material ◽  
Single Layer ◽  
Metal Substrate ◽  
Single Atom ◽  
Metal Interaction ◽  
Wide Range ◽  
Metal Metal ◽  
Sulphur Vacancy

Layered materials, such as \ce{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 ultra-thin diffusion barriers in semi-conductor device interconnects and as supports for low dimensional metal catalysts. Understanding the interaction between metals and the \ce{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 \ce{MoS2}. We explore how the metal-substrate and metal-metal interactions contribute to the stability of metal clusters on \ce{MoS2}, and how these interactions change in the presence of a sulphur vacancy, to develop insight to allow prediction of thin film morphology. The strength of interaction between the metals and \ce{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 \ce{MoS2}, while Ru prefers 3D structures on \ce{MoS2}. However, the presence of a sulphur 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 \ce{MoS2} as a suitable candidate for advanced interconnects, while Ru on \ce{MoS2} is more suited to catalysis applications.

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.

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

Theoretical investigation on the photocatalytic activity of the Au/g-C3N4 monolayer

2017 ◽  
Vol 16 (02) ◽  
pp. 1750013 ◽  
Author(s):  
Guoyan Nie ◽  
Peng Li ◽  
Jin-Xia Liang ◽  
Chun Zhu
Keyword(s):  
Optical Properties ◽  
Photocatalytic Activity ◽  
Density Functional ◽  
High Stability ◽  
Carbon Nitride ◽  
Visible Region ◽  
Single Layer ◽  
Single Atom ◽  
Two Dimensional ◽  
Hybrid Functional

Two-dimensional optical catalysis materials have a wonderful potential application. Here, a new two-dimensional material consisting of the supported single-atom Au on a graphite carbon nitride (g-C3N[Formula: see text] single layer has been designed and its electronic and optical properties have been characterized by density functional calculations. The bandgap of 1.82[Formula: see text]eV calculated by the hybrid functional HSE06 shows that the Au/g-C3N4 is an indirect semiconductor, and the electron can easily be excited from the single-atom Au to the bottom of the conduction band. This material therefore has relatively strong optical properties in the visible region. Moreover, the process of Au insertion into the cavity of g-C3N4 single layer is energy-favorable. This work may provide insights and a new avenue for fabricating supported Au catalysts with high stability.

Diphthalocyanine metal complexes and their analogues

2000 ◽  
Vol 04 (04) ◽  
pp. 340-343 ◽  
Author(s):  
CLAUDIO ERCOLANI
Keyword(s):  
Density Functional ◽  
Redox Properties ◽  
Single Atom ◽  
Linear Optics ◽  
Electrochromic Devices ◽  
Practical Applications ◽  
Non Linear Optics ◽  
Metal Metal ◽  
Sandwich Type ◽  
Available Information

The present overview deals with ditetrapyrrolic macrocycles, mainly diphthalocyanine systems, of the following three classes: (a) sandwich-type molecules (I); (b) metal-metal bonded systems (II); (c) single-atom bridged dimers (III). The available information focuses on the structural and electronic features, redox properties and partial oxidation. Practical applications, e.g. electrochromic devices, molecular metals, liquid crystals, non-linear optics, etc., make these classes of complexes particularly attractive and promising materials. The bonding mechanism and the structural, magnetic, conductive and optical properties of these systems are elucidated by density functional calculations.

scholarly journals Visualizing band structure hybridization and superlattice effects in twisted MoS2/WS2 heterobilayers

2D Materials ◽  
2021 ◽  
Author(s):  
Alfred J. H. Jones ◽  
Ryan Muzzio ◽  
Sahar Pakdel ◽  
Deepnarayanan Biswas ◽  
Davide Curcio ◽  
...  
Keyword(s):  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Twist Angle ◽  
Electronic States ◽  
Single Layer ◽  
Density Functional Theory Calculations ◽  
Layer Transition ◽  
Electronic Band ◽  
Wide Range

Abstract A mismatch of atomic registries between single-layer transition metal dichalcogenides (TMDs) in a two dimensional van der Waals heterostructure produces a moiré superlattice with a periodic potential, which can be fine-tuned by introducing a twist angle between the materials. This approach is promising both for controlling the interactions between the TMDs and for engineering their electronic band structures, yet direct observation of the changes to the electronic structure introduced with varying twist angle has so far been missing. Here, we probe heterobilayers comprised of single-layer MoS2 and WS2 with twist angles ranging from 2° to 20° and determine the twist angle-dependent evolution of the electronic band structure using micro-focused angle-resolved photoemission spectroscopy. We find strong interlayer hybridization between MoS2 and WS2 electronic states at the Γ-point of the Brillouin zone, leading to a shift of the valence band maximum in the heterostructure. Replicas of the hybridized states are observed at the centre of twist angle-dependent moiré mini Brillouin zones. We confirm that these replica features arise from the inherent moiré potential by comparing our experimental observations with density functional theory calculations of the superlattice dispersion. Our direct visualization of these features underscores the potential of using twisted heterobilayer semiconductors to engineer hybrid electronic states and superlattices that alter the electronic and optical properties of 2D heterostructures for a wide range of twist angles.

Intrinsic Stacking Interactions of Natural and Artificial Nucleobases

2019 ◽  
Author(s):  
Drew P. Harding ◽  
Laura J. Kingsley ◽  
Glen Spraggon ◽  
Steven Wheeler
Keyword(s):  
Gas Phase ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Molecular Descriptors ◽  
Stacking Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Binding Partner ◽  
Heavy Atoms ◽  
Wide Range

The intrinsic (gas-phase) stacking energies of natural and artificial nucleobases were explored using density functional theory (DFT) and correlated ab initio methods. Ranking the stacking strength of natural nucleobase dimers revealed a preference in binding partner similar to that seen from experiments, namely G > C > A > T > U. Decomposition of these interaction energies using symmetry-adapted perturbation theory (SAPT) showed that these dispersion dominated interactions are modulated by electrostatics. Artificial nucleobases showed a similar stacking preference for natural nucleobases and were also modulated by electrostatic interactions. A robust predictive multivariate model was developed that quantitively predicts the maximum stacking interaction between natural and a wide range of artificial nucleobases using molecular descriptors based on computed electrostatic potentials (ESPs) and the number of heavy atoms. This model should find utility in designing artificial nucleobase analogs that exhibit stacking interactions comparable to those of natural nucleobases. Further analysis of the descriptors in this model unveil the origin of superior stacking abilities of certain nucleobases, including cytosine and guanine.

Efficient Prediction of Structural and Electronic Properties of Hybrid 2D Materials Using DFT and Machine Learning

2018 ◽  
Author(s):  
Sherif Tawfik ◽  
Olexandr Isayev ◽  
Catherine Stampfl ◽  
Joseph Shapter ◽  
David Winkler ◽  
...  
Keyword(s):  
Machine Learning ◽  
Band Gap ◽  
Density Functional ◽  
2D Materials ◽  
Van Der Waals ◽  
Building Blocks ◽  
Machine Learning Techniques ◽  
Interlayer Distance ◽  
Computational Screening ◽  
Wide Range

Materials constructed from different van der Waals two-dimensional (2D) heterostructures offer a wide range of benefits, but these systems have been little studied because of their experimental and computational complextiy, and because of the very large number of possible combinations of 2D building blocks. The simulation of the interface between two different 2D materials is computationally challenging due to the lattice mismatch problem, which sometimes necessitates the creation of very large simulation cells for performing density-functional theory (DFT) calculations. Here we use a combination of DFT, linear regression and machine learning techniques in order to rapidly determine the interlayer distance between two different 2D heterostructures that are stacked in a bilayer heterostructure, as well as the band gap of the bilayer. Our work provides an excellent proof of concept by quickly and accurately predicting a structural property (the interlayer distance) and an electronic property (the band gap) for a large number of hybrid 2D materials. This work paves the way for rapid computational screening of the vast parameter space of van der Waals heterostructures to identify new hybrid materials with useful and interesting properties.

The Future of Plasma-Based Surface Engineering Techniques in Tribology (Keynote)

2005 ◽  
Author(s):  
Allan Matthews ◽  
Adrian Leyland
Keyword(s):  
Surface Engineering ◽  
Performance Enhancement ◽  
Bulk Material ◽  
Cost Savings ◽  
Cost Effective ◽  
Ceramic Coatings ◽  
Performance Improvements ◽  
Treatment Techniques ◽  
Wide Range ◽  
Macro Scale

Over the past twenty years or so, there have been major steps forward both in the understanding of tribological mechanisms and in the development of new coating and treatment techniques to better “engineer” surfaces to achieve reductions in wear and friction. Particularly in the coatings tribology field, improved techniques and theories which enable us to study and understand the mechanisms occurring at the “nano”, “micro” and “macro” scale have allowed considerable progress to be made in (for example) understanding contact mechanisms and the influence of “third bodies” [1–5]. Over the same period, we have seen the emergence of the discipline which we now call “Surface Engineering”, by which, ideally, a bulk material (the ‘substrate’) and a coating are combined in a way that provides a cost-effective performance enhancement of which neither would be capable without the presence of the other. It is probably fair to say that the emergence and recognition of Surface Engineering as a field in its own right has been driven largely by the availability of “plasma”-based coating and treatment processes, which can provide surface properties which were previously unachievable. In particular, plasma-assisted (PA) physical vapour deposition (PVD) techniques, allowing wear-resistant ceramic thin films such as titanium nitride (TiN) to be deposited on a wide range of industrial tooling, gave a step-change in industrial productivity and manufactured product quality, and caught the attention of engineers due to the remarkable cost savings and performance improvements obtained. Subsequently, so-called 2nd- and 3rd-generation ceramic coatings (with multilayered or nanocomposite structures) have recently been developed [6–9], to further extend tool performance — the objective typically being to increase coating hardness further, or extend hardness capabilities to higher temperatures.

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