THEORETICAL STUDY OF THE ADSORPTION AND DIFFUSION OF OXYGEN ATOM ON O-TERMINATED ZnO$(000\bar 1)$ SURFACE

NANO ◽  
2014 ◽  
Vol 09 (01) ◽  
pp. 1450006 ◽  
Author(s):  
LIANG QIAO ◽  
YI ZENG ◽  
CHAOQUN QU ◽  
XIAOYING HU ◽  
LIJUN SONG ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Density Functional ◽  
Theoretical Study ◽  
Adsorbed Oxygen ◽  
Surface Relaxation ◽  
Functional Theory ◽  
Potential Barriers ◽  
Surface Work ◽  
Adsorbed Oxygen Atom ◽  
And Diffusion

The adsorption and diffusion of oxygen atom on the O -terminated ZnO [Formula: see text] surface have been systematically investigated based on first-principles density functional theory. The results show that the surface relaxation of the ZnO [Formula: see text] surface is significant. In the view of the maximization of the adsorption energy, the preferred site for the adsorption of oxygen atom is the top- O site above the oxygen atom of the first Zn – O bilayer. There is chemical bond formed between the adsorbed oxygen atom and the oxygen atom on the surface, which will result in the redistribution of the charges. The charges transfer from the ZnO surface to the adsorbed oxygen atom, which will heighten the surface potential of ZnO surface and increase the surface work function. Moreover, the diffusion of the oxygen atom on the ZnO surface has also been investigated, and the potential barriers of the diffusion have been identified to reveal the adsorption stability.

A theoretical study on the intercalation and diffusion of AlF3 in graphite: its application in rechargeable batteries

2021 ◽  
Vol 23 (35) ◽  
pp. 19579-19589
Author(s):  
Sindy J. Rodríguez ◽  
Adriana E. Candia ◽  
Mario C. G. Passeggi ◽  
Eduardo A. Albanesi ◽  
Gustavo D. Ruano
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Rechargeable Batteries ◽  
Aluminum Fluoride ◽  
First Principles Calculations ◽  
Functional Theory ◽  
And Diffusion

Using first-principles calculations based on density functional theory (DFT), we study the aluminum fluoride (AlF3) intercalation in graphite as a new possibility to use this molecule in rechargeable batteries, and understand its role when used as a component of the solvent.

Oxygen adsorption and diffusion on an Al(111) surface and subsurface: a theoretical study

2016 ◽  
Vol 94 (6) ◽  
pp. 541-546
Author(s):  
Su-Qin Zhou ◽  
Yang-Yang Wu ◽  
Si-Yu Xu ◽  
Feng-Qi Zhao ◽  
Xue-Hai Ju
Keyword(s):  
Oxygen Atom ◽  
Density Functional ◽  
Oxygen Adsorption ◽  
Adsorbed Oxygen ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Adsorption Heats ◽  
Surface Increase ◽  
Oxygen Atoms

The generalized gradient approximation of the density functional theory was used to investigate the adsorption and dissociation of the O2 molecule on an Al(111) surface and the subsequent diffusion of an oxygen atom into the subsurface with different oxygen coverages. The total adsorption energies of oxygen atoms on the Al(111) surface increase as the number of adsorbed oxygen atoms increases, while the adsorption heats per oxygen atom decrease firstly and then increase. The adsorption heats for O2 physisorption on the Al(111) surface would increase as the oxidization degree of Al(111) surface increased. As the oxidization degree of Al(111) surface increases, the adsorption heats for O2 chemisorption decrease firstly and then increase, and the O2 molecule would not dissociate when the oxidization degree was up to 1.0 monolayer. In general, the energy barriers for both the interlayer and intralayer diffusions of the oxygen atom on the Al(111) surface would become larger as the number of initial adsorbed oxygen atoms on the Al(111) surface increased due to an increasing repulsion force.

scholarly journals Oxygen Atom Function: The Case of Methane Oxidation Mechanism to Synthesis Gas over a Pd Cluster

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 666
Author(s):  
Yuanyuan Meng ◽  
Yuyuan Xue ◽  
Chuanmin Ding ◽  
Xiaofeng Gao ◽  
Kan Zhang ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Density Functional ◽  
Oxidation Mechanism ◽  
Functional Theory ◽  
Oxidation Of Methane ◽  
Rate Limiting Step ◽  
Adsorbed Oxygen Atom ◽  
Kinetic Calculations ◽  
Rate Limiting

A dimer model Pd2 was established to study the adsorption of CHx (x = 1–4) and CH4 dehydrogenation, as well as syngas formation using density functional theory (DFT) at the atomic level. Meanwhile, insight into understanding the role of the oxygen atom on the partial oxidation of methane (POM) was also calculated based on a trimer model of Pd2O. For the adsorption of CHx, results showed that the presence of an oxygen atom was a disadvantage to the adsorption of CHx (x = 1–3) species. For CH4 dissociation, the process of CH2→CH + H was found to be the rate-limiting step (RSD) on both Pd2 and Pd2O. H2 was formed by the reaction of CH2 + 2H→CH2 + H2. For CO formation, it was primarily formed in the process of CH + O→CHO→CO + H on both the Pd2 and the Pd2O catalyst. Thermodynamic and kinetic calculations revealed that formation and maintainance of the oxygen atom on the Pd surface could promote a POM reaction to achieve high H2 and CO yield and selectivity. Our study provides a helpful understanding of the effect of an adsorbed oxygen atom on a POM reaction with a Pd catalyst.

THEORETICAL STUDY ON THE INTERNAL ROTATION OF NITROTYL OF BENZALDOXIMES

2006 ◽  
Vol 05 (01) ◽  
pp. 111-120
Author(s):  
GUOPING LI ◽  
WEIREN XU ◽  
CHAOJUN ZHANG ◽  
JIANWU WANG ◽  
CHENGBU LIU
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Rotation Barrier ◽  
Functional Theory ◽  
Potential Barriers ◽  
Internal Rotations ◽  
Small Influence ◽  
Calculation Results ◽  
Method Of Density Functional

The internal rotations of nitrotyl around the bond C–C in Z- and E-benzaldoximes and their various substituted species have been investigated theoretically by the method of density functional theory (DFT) at the B3LYP/6-31G* level. The corresponding rotation transition states have been optimized. The potential barriers and the rates of the internal rotations of various species have been calculated. The rotation barrier of Z-benzaldoxime is lower than that of E-isomer. The para-substitution has only a small influence on the rotation barriers. The conjugations are consolidated in the acidic and basic species of both Z- and E-isomers. The experimental NMR spectrums of Z- and E-benzaldoxime are explained based on the calculation results.

scholarly journals Theoretical Study of Zirconium Isomorphous Substitution into Zeolite Frameworks

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4466
Author(s):  
Duichun Li ◽  
Bin Xing ◽  
Baojun Wang ◽  
Ruifeng Li
Keyword(s):  
Acid Site ◽  
Density Functional ◽  
Theoretical Study ◽  
Atomic Radius ◽  
Acid Sites ◽  
Isomorphous Substitution ◽  
Dispersion Correction ◽  
Brønsted Acidity ◽  
Functional Theory ◽  
Brönsted Acidity

Systematic periodic density functional theory computations including dispersion correction (DFT-D) were carried out to determine the preferred location site of Zr atoms in sodalite (SOD) and CHA-type topology frameworks, including alumino-phosphate-34 (AlPO-34) and silico-alumino-phosphate-34 (SAPO-34), and to determine the relative stability and Brönsted acidity of Zr-substituted forms of SOD, AlPO-34, and SAPO-34. Mono and multiple Zr atom substitutions were considered. The Zr substitution causes obvious structural distortion because of the larger atomic radius of Zr than that of Si, however, Zr-substituted forms of zeolites are found to be more stable than pristine zeolites. Our results demonstrate that in the most stable configurations, the preferred favorable substitutions of Zr in substituted SOD have Zr located at the neighboring sites of the Al-substituted site. However, in the AlPO-34 and SAPO-34 frameworks, the Zr atoms are more easily distributed in a dispersed form, rather than being centralized. Brönsted acidity of substituted zeolites strongly depends on Zr content. For SOD, substitution of Zr atoms reduces Brönsted acidity. However, for Zr-substituted forms of AlPO-34 and SAPO-34, Brönsted acidity of the Zr-O(H)-Al acid sites are, at first, reduced and, then, the presence of Zr atoms substantially increased Brönsted acidity of the Zr-O(H)-Al acid site. The results in the SAPO-34-Zr indicate that more Zr atoms substantially increase Brönsted acidity of the Si-O(H)-Al acid site. It is suggested that substituted heteroatoms play an important role in regulating and controlling structural stability and Brönsted acidity of zeolites.

scholarly journals DFT Study of the Electronic Structure of Cubic-SiC Nanopores with a C-Terminated Surface

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Calvino ◽  
A. Trejo ◽  
M. I. Iturrios ◽  
M. C. Crisóstomo ◽  
Eliel Carvajal ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Surface Passivation ◽  
Phase Changes ◽  
Surface Relaxation ◽  
Oh Radicals ◽  
Functional Theory ◽  
Band Gap Engineering ◽  
Chemical Surface

A study of the dependence of the electronic structure and energetic stability on the chemical surface passivation of cubic porous silicon carbide (pSiC) was performed using density functional theory (DFT) and the supercell technique. The pores were modeled by removing atoms in the [001] direction to produce a surface chemistry composed of only carbon atoms (C-phase). Changes in the electronic states of the porous structures were studied by using different passivation schemes: one with hydrogen (H) atoms and the others gradually replacing pairs of H atoms with oxygen (O) atoms, fluorine (F) atoms, and hydroxide (OH) radicals. The results indicate that the band gap behavior of the C-phase pSiC depends on the number of passivation agents (other than H) per supercell. The band gap decreased with an increasing number of F, O, or OH radical groups. Furthermore, the influence of the passivation of the pSiC on its surface relaxation and the differences in such parameters as bond lengths, bond angles, and cell volume are compared between all surfaces. The results indicate the possibility of nanostructure band gap engineering based on SiC via surface passivation agents.

Sign in / Sign up

Export Citation Format

Share Document