First Principle Study of Hydrazine and OH- Co-Adsorption on Ni(111) in High Coverage System

2014 ◽  
Vol 893 ◽  
pp. 35-38 ◽  
Author(s):  
Andam Deatama Refino ◽  
Mohammad Kemal Agusta ◽  
Hermawan Kresno Dipojono ◽  
Nugraha
Keyword(s):  
Density Functional ◽  
Co Adsorption ◽  
Stable Configuration ◽  
Nickel Surface ◽  
Gauche Conformation ◽  
High Coverage ◽  
Adsorption Mechanisms ◽  
Adsorption Sites ◽  
The Stability ◽  
In Cis

Theoretical investigation of co-adsorption process between hydrazine (N2H4) and OH- on Ni(111) is performed using density functional theory. OH- adsorption mechanisms at various adsorption sites as well as its interaction with hydrazine in various conformations (anti, cis, and gauche) are studied. The stability of OH- adsorption on nickel surface is significantly influenced by the presence of hydrazine molecule. Among the three conformations of hydrazine, OH- adsorption on nickel surface doesn't occur in cis conformation. Otherwise, co-adsorption occurs in system with gauche and anti conformation. In anti system, hydrazine conformation is transformed during relaxation process and forms gauche conformation as the most stable configuration of the system.

CO Coverage Effects on Pt(111) from First-Principles Calculations

2008 ◽  
Vol 1084 ◽  
Author(s):  
Bin Shan ◽  
Ligen Wang ◽  
Jangsuk Hyun ◽  
Yang Sang ◽  
Yujun Zhao ◽  
...  
Keyword(s):  
Density Functional ◽  
Co Adsorption ◽  
Oxidation Catalysis ◽  
Energy Curve ◽  
High Coverage ◽  
Functional Theory ◽  
Diesel Oxidation ◽  
Saturation Coverage ◽  
Differential Binding ◽  
The Stability

ABSTRACTCO saturation coverage on Pt(111) is crucially important in diesel oxidation catalysis. We systematically studied high coverage CO adsorption on the Pt(111) surface using density functional theory (DFT) calculations and classical Monte Carlo (MC) simulations. The zero-coverage limit CO adsorption energy at different binding sites is almost degenerate at the revised Perdew–Burke–Erzernhof functional (RPBE) level. As CO populates the surface, strong through-space repulsion and substrate-mediated metal sharing tends to dominate the stability of adsorbates and alter their binding preferences. The calculated differential binding energy curve and adsorption patterns compare well with experiments.

First-Principle Studies on the Stability of AlN(0001)/NbB2(0001) Interface

2014 ◽  
Vol 1052 ◽  
pp. 18-23
Author(s):  
Hui Zhao ◽  
Kai Yuan Liu ◽  
Qian Han
Keyword(s):  
Density Functional Theory ◽  
Energy Density ◽  
Density Functional ◽  
Stable Configuration ◽  
Stable Model ◽  
First Principle ◽  
Total Energy Density ◽  
Energy Density Functional ◽  
Functional Theory ◽  
The Stability

The stability behaviour of AlN(0001)/NbB2(0001) interface was calculated by first-principle total-energy density functional theory. The calculation indicated that the stable NbB2(0001) surface is B terminated. We joined the AlN(0001) slab and the NbB2(0001) slab with different terminations together to construct all possible AlN(0001)/NbB2(0001) interface models, and calculated their interface energies to confirm the relatively stable model. We concluded that the structure with Al is on top of B in the interface AlN (0001)/NbB2(0001) is the most stable configuration.

High coverage adsorption and co-adsorption of CO and H2 on Ru(0001) from DFT and thermodynamics

2015 ◽  
Vol 17 (29) ◽  
pp. 19446-19456 ◽  
Author(s):  
Peng Zhao ◽  
Yurong He ◽  
Dong-Bo Cao ◽  
Xiaodong Wen ◽  
Hongwei Xiang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Co Adsorption ◽  
High Coverage ◽  
Functional Theory ◽  
Adsorption Of Co ◽  
Atomistic Thermodynamics

The adsorption and co-adsorption of CO and H2 at different coverages on p(4 × 4) Ru(0001) have been computed using periodic density functional theory (GGA-RPBE) and atomistic thermodynamics.

scholarly journals DFT-Based Studies on Carbon Adsorption on the wz-GaN Surfaces and the Influence of Point Defects on the Stability of the Diamond–GaN Interfaces

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6532
Author(s):  
Malgorzata Sznajder ◽  
Roman Hrytsak
Keyword(s):  
Density Functional ◽  
High Electron Mobility Transistors ◽  
Growth Direction ◽  
First Principles Calculation ◽  
High Electron ◽  
Interfacial Layers ◽  
Adsorption Sites ◽  
Carbon Adsorption ◽  
The Stability ◽  
Reliability Performance

Integration of diamond with GaN-based high-electron-mobility transistors improves thermal management, influencing the reliability, performance, and lifetime of GaN-based devices. The current GaN-on-diamond integration technology requires precise interface engineering and appropriate interfacial layers. In this respect, we performed first principles calculation on the stability of diamond–GaN interfaces in the framework of density functional theory. Initially, some stable adsorption sites of C atoms were found on the Ga- and N-terminated surfaces that enabled the creation of a flat carbon monolayer. Following this, a model of diamond–GaN heterojunction with the growth direction [111] was constructed based on carbon adsorption results on GaN{0001} surfaces. Finally, we demonstrate the ways of improving the energetic stability of diamond–GaN interfaces by means of certain reconstructions induced by substitutional dopants present in the topmost GaN substrate’s layer.

Interaction of CO with Gold Under Gas Phase and Electrochemical Environments

2020 ◽  
Author(s):  
Sudarshan Vijay ◽  
Thomas Vagn Hogg ◽  
Johan Ehlers ◽  
Henrik Høgh Kristoffersen ◽  
Yu Katayama ◽  
...  
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Co Adsorption ◽  
Density Functional Theory Calculations ◽  
Underpotential Deposition ◽  
Attenuated Total Reflection ◽  
Ab Initio Molecular Dynamics ◽  
Adsorption Sites ◽  
Temperature Programmed ◽  
Dynamics Simulations

<div> <div> <div> <p>We present a joint theoretical-experimental study of CO coverage on Au under both gas phase and electrochemical conditions. By analyzing temperature programmed desorption (TPD) spectra on (211) and (310) surface facets, we show that, under atmospheric CO pressure, the steps of both facets adsorb up to 0.7 ML coverage of *CO, while the terraces have close to zero coverage. We show this result to be consistent with density functional theory calculations of adsorption energies. Under electrochemical conditions on polycrystalline Au, we investigate the CO binding with in situ attenuated total reflection surface enhanced IR spectra (ATR-SEIRAS). We detect a CO band at 0.2V vs. SHE that disappears upon partial Pb underpotential deposition (facet selective), which suggests Pb blocks the CO adsorption sites. With Pb underpotential deposition on single crystals and theoretical surface Pourbaix analysis, we narrow down the possible adsorption sites of CO to open site motifs: (211) and (110) steps, as well as (100) terraces. Ab initio molecular dynamics simulations of explicit water at the Au surface, however, shows the adsorption of CO on (211) steps to be significantly weakened relative to the (100) terrace due to competitive water adsorption. This result suggests that CO is more likely to bind to the (100) terrace than steps in an electrochemical environment. The competition between water and CO adsorption can result in different binding sites for *CO on Au in gas phase and electrochemical environments. </p> </div> </div> </div>

The stability of graphene-based Möbius strip with vacancy and at high-temperature

2018 ◽  
Vol 32 (31) ◽  
pp. 1850350
Author(s):  
Kaishuai Yang ◽  
Chuanguo Zhang ◽  
Xiaohong Zheng ◽  
Xianlong Wang ◽  
Zhi Zeng
Keyword(s):  
Density Functional ◽  
Md Simulations ◽  
Melting Behavior ◽  
Stable Configuration ◽  
Möbius Strip ◽  
Functional Theory ◽  
Melting Temperatures ◽  
Structural And Electronic Properties ◽  
The Stability ◽  
Mobius Strip

The structural and electronic properties of mono-vacancy (MV) defect in graphene-based Möbius strip (GMS) are studied in the framework of density functional theory (DFT) combined with the molecular dynamics (MD) simulations. Two kinds of MV defects are observed: the 59-type MV (a configuration with one pentagon and one nonagon ring) located at the curved areas of Möbius strip, and the 5566-type MV (a configuration with two pentagon and two hexagon rings) with one sp3 hybridized carbon appeared in the twisted areas. The 5566-type MV defect is the most stable configuration at 0 K, while the DFT-MD calculations show that it is unstable at room-temperature and will transform into a 59-type MV. Additionally, the melting behavior of GMSs is investigated through empirical potential MD simulations, and we find that their melting temperatures are about 2750 K, which is lower than that of carbon nanotubes and graphene.

scholarly journals Adsorption of 4,4″-Diamino-p-Terphenyl on Cu(001): A First-Principles Study

Surfaces ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 31-38
Author(s):  
Chang-Tian Wang ◽  
Yan-Fang Zhang ◽  
Shixuan Du
Keyword(s):  
First Principles ◽  
Rotation Angle ◽  
Electronic Devices ◽  
Molecular Devices ◽  
Stable Configuration ◽  
First Principles Calculations ◽  
Adsorption Sites ◽  
Points Of View ◽  
The Stability ◽  
Molecule Surface

Single-molecular devices show remarkable potential for applications in downscale electronic devices. The adsorption behavior of a molecule on a metal surface is of great importance from both fundamental and technological points of view. Herein, based on first-principles calculations, the adsorption of a 4,4″-diamino-p-terphenyl (DAT) molecule on a Cu(001) surface has been systematically explored. The most stable configuration is the DAT molecule lying flat with a rotation angle of 13° relative to the [100] surface direction. It was found that the adsorption sites of benzene rings and nitrogen atoms in the DAT molecule have important influences on the stability of the adsorption configuration. Electron density differences analysis shows that the electrons accumulate at the DAT-Cu(001) interface. The density of states projected on a DAT molecule of DAT/Cu(001) exhibits a metallic character, while the freestanding ones are semiconducting, indicating a strong interaction between the DAT molecule and the Cu(001) surface in the most stable adsorption configuration. These results provide useful information for tuning the properties and functions of DAT molecules, and may offer useful insights for other organic molecule/surface systems.

Stability of Adsorbed Water on TiO2-TiN Interfaces. A First Principles and Ab Initio Thermodynamics Investigation.

2018 ◽  
Author(s):  
Michael Nolan ◽  
Julio Gutierrez ◽  
Pierre Loverra ◽  
Marco Fronzi ◽  
Alan O'Riordan
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Adsorbed Water ◽  
Free Energy Calculations ◽  
Ambient Conditions ◽  
High Concentration ◽  
High Coverage ◽  
Reducing Conditions ◽  
Atomistic Thermodynamics ◽  
The Stability

Titanium Nitride (TiN) surfaces can oxidise and the growth of a TiO<sub>x</sub> layer on the surface along with the likely presence of water in the surrounding environment can modify the properties of this widely used coating material. The present Density Functional Theory study, including Hubbard +U correction (DFT+U), investigates the stability of adsorbed water at TiO<sub>2</sub>-TiN interfaces with different defects, that serve as a model for an oxide layer grown on a TiN surface. Surface free energy calculations show the stability of perfect TiN-TiO<sub>2</sub> interface at regular O pressures, while oxygen vacancy-rich TiO<sub>1.88</sub>–TiN is more favourable at reducing conditions. An isolated water is preferentially adsorbed dissociatively at perfect and oxygen defective interfaces while molecular adsorption is more stable at higher coverages. The adsorption energy is stronger at the oxygen defective interfaces which arises from the high concentration of reduced Ti<sup>3+</sup> and strong interfacial atomic relaxations. Ab initio atomistic thermodynamics show that water will be present at high coverage on TiO<sub>2</sub>-TiN interfaces at ambient conditions and the pristine interface is only stable at very low pressure of O and H<sub>2</sub>O. The results of these DFT+U simulations are important for the fundamental understanding of wettability of interfacial systems involving metal oxides.

XPS CHEMICAL SHIFTS FOR CO ADSORBED ON Ni(100): A THEORETICAL STUDY

1995 ◽  
Vol 02 (05) ◽  
pp. 563-568 ◽  
Author(s):  
L. PEDOCCHI ◽  
G. ROVIDA ◽  
N. RUSSO
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
Co Adsorption ◽  
Density Functional Method ◽  
Functional Method ◽  
Adsorption Sites ◽  
Metal Atoms ◽  
Structure Sensitive ◽  
Adsorption Of Co ◽  
Adsorption Geometry

Starting from the observed chemical shift of C-1s and O-1s ionization potentials (IP), reported in the literature for the adsorption of CO on Ni (100), and correlated to the different CO adsorption sites at different coverages, we have carried out a theoretical investigation, using a first-principle density-functional method, to calculate ionization energies for adsorbed CO in the atop and bridge sites. In our approach, the Ni (100) surface was simulated with clusters of up to nine metal atoms of different geometry, in order to test the two adsorption sites. For each cluster, the CO adsorption geometry was optimized and the O-1s and C-1s ionizations were calculated. The main result was that the (O-1s–C-1s) difference was very well reproduced even with clusters of modest size, thus confirming the possibility to use this value as a structure-sensitive parameter.

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