Roles of Oxygen Vacancies of CeO2 and Mn-Doped CeO2 with the Same Morphology in Benzene Catalytic Oxidation

Mn-doped CeO2 and CeO2 with the same morphology (nanofiber and nanocube) have been synthesized through hydrothermal method. When applied to benzene oxidation, the catalytic performance of Mn-doped CeO2 is better than that of CeO2, due to the difference of the concentration of O vacancy. Compared to CeO2 with the same morphology, more oxygen vacancies were generated on the surface of Mn-doped CeO2, due to the replacement of Ce ion with Mn ion. The lattice replacement has been analyzed through XRD, Raman, electron energy loss spectroscopy and electron paramagnetic resonance technology. The formation energies of oxygen vacancy on the different exposed crystal planes such as (110) and (100) for Mn-doped CeO2 were calculated by the density functional theory (DFT). The results show that the oxygen vacancy is easier to be formed on the (110) plane. Other factors influencing catalytic behavior have also been investigated, indicating that the surface oxygen vacancy plays a crucial role in catalytic reaction.

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Conversion of syngas into light olefins over bifunctional ZnCeZrO/SAPO-34 catalysts: regulation of the surface oxygen vacancy concentration and its relation to the catalytic performance

Catalysis Science & Technology ◽

10.1039/d0cy01759k ◽

2021 ◽

Author(s):

Yaoya Luo ◽

Sen Wang ◽

Shujia Guo ◽

Kai Yuan ◽

Hao Wang ◽

...

Keyword(s):

Oxygen Vacancy ◽

Oxygen Vacancies ◽

Vacancy Concentration ◽

Catalytic Performance ◽

Light Olefins ◽

Oxygen Vacancy Concentration ◽

Surface Oxygen ◽

Surface Oxygen Vacancy

Surface oxygen vacancies can improve the formation of methanol intermediates and promote their evolution into olefin products for syngas-to-olefins over Zn0.5CeZrOx/SAPO-34.

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Oxygen Vacancies in Amorphous HfO2 and SiO2

MRS Proceedings ◽

10.1557/proc-1073-h01-01 ◽

2008 ◽

Vol 1073 ◽

Cited By ~ 2

Author(s):

Chioko Kaneta ◽

Takahiro Yamasaki

Keyword(s):

First Principles ◽

Density Functional ◽

Formation Energy ◽

Oxygen Vacancies ◽

Gate Dielectrics ◽

Propagation Mechanism ◽

Functional Theory ◽

The Density Functional Theory ◽

The Difference ◽

Formation Energies

ABSTRACTFormation energies and electronic properties of oxygen vacancies in amorphous HfO2 gate dielectrics are investigated by employing the first-principles method based on the density functional theory. We have found that the formation energy of neutral oxygen vacancy in amorphous HfO2 distributes from 4.7 to 6.1 eV, most of which is lower than the value for cubic HfO2, 6.0 eV. We also investigated the stabilities of the Vo pairs in various charged state and compared with those in amorphous SiO2. We found that Vo++ is stabilized in the vicinity of Vo in SiO2. In HfO2, however, this does not happen. This suggests the difference of defect propagation mechanism in HfO2 and SiO2.

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On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation

Catalysts ◽

10.3390/catal9040312 ◽

2019 ◽

Vol 9 (4) ◽

pp. 312 ◽

Cited By ~ 2

Author(s):

Antonella Glisenti ◽

Andrea Vittadini

Keyword(s):

Catalytic Activity ◽

Co Oxidation ◽

Density Functional Calculations ◽

Density Functional ◽

Formation Energy ◽

Oxygen Vacancies ◽

Catalytic Performance ◽

Energy Profiles ◽

High Concentrations ◽

3D Impurities

The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts.

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Study on the optical spectra of the oxygen vacancy in ZnWO4 crystal

Modern Physics Letters B ◽

10.1142/s0217984921504716 ◽

2021 ◽

pp. 2150471

Author(s):

Gaiping Lian ◽

Tingyu Liu ◽

Le Yu

Keyword(s):

Oxygen Vacancy ◽

Density Functional ◽

Defect Formation ◽

Finite Size ◽

Optical Spectra ◽

Functional Method ◽

Hybrid Functional ◽

Electron Phonon Coupling ◽

Correction Scheme ◽

The Density Functional Theory

ZnWO4 is easy to color, which will reduce the luminous efficiency of the crystal and limit the application of the crystal. In order to study the origin of the color in the crystal, in this paper, the effects of the oxygen vacancy on the optical properties for the ZnWO4 crystal have been studied based on the density functional theory (DFT). The hybrid functional method (HSE) and the finite-size correction scheme (FNV) are used to correct the band edge problem and eliminate the artificial interaction of the charged defects, respectively. On the basis of the corrected defect formation energy, we obtain the optical spectra of the [Formula: see text] and [Formula: see text] centers containing electron-phonon coupling. The calculated absorption and luminescence peaks are at 2.54 eV and 0.79 eV for the [Formula: see text] center and at 2.98 eV and 1.09 eV for the [Formula: see text] center, respectively. The calculated absorption band of the [Formula: see text] center is close to the experimental value of 2.48 eV (500 nm), so we speculate that the coloring of the ZnWO4 crystal is related to the [Formula: see text] center. Meanwhile, the existence of oxygen vacancy makes ZnWO4 crystal to have self-absorption and to increase decay time, which greatly affects the scintillation properties of the crystal.

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Oxygen vacancy migration in CSZ using density functional theory

MRS Proceedings ◽

10.1557/proc-1122-o03-08 ◽

2008 ◽

Vol 1122 ◽

Author(s):

Byeong-Eon Lee ◽

Dae-Hee Kim ◽

Yeong-Cheol Kim

Keyword(s):

Density Functional Theory ◽

Oxygen Vacancy ◽

Density Functional ◽

Oxygen Vacancies ◽

Nearest Neighbor ◽

Functional Theory ◽

The Third ◽

Vacancy Migration ◽

Neighbor Site ◽

Formation Energies

AbstractWe studied oxygen migration in calcia-stabilized cubic zirconia (CSZ) using density functional theory. A Ca atom was substituted for a Zr atom in a 2×2×2 ZrO2 cubic supercell, and an oxygen vacancy was produced to satisfy the charge neutrality condition. We found that the formation energies of an oxygen vacancy, as a function of its location with respect to the Ca atom, were varied. The relative formation energies of the oxygen vacancies located at the first-, second-, third-, and fourth-nearest-neighbors were 0.0, −0.07, 0.19, and 0.19 eV, respectively. Therefore, the oxygen vacancy located at the second-nearest-neighbor site of the Ca atom was the most favorable, the oxygen vacancy located at the first-nearest-neighbor site was the second most favorable, and the oxygen vacancies at the third- and fourth-nearest-neighbor sites were the least favorable. We also calculated the energy barriers for the oxygen vacancy migration between oxygen sites. The energy barriers between the first and the second nearest sites, the second and third nearest sites, and the third and fourth nearest sites were 0.11, 0.46, and 0.23 eV, respectively. Therefore, the oxygen vacancies favored the first- and second-nearest-neighbor oxygen sites when they drifted under an electric field.

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First principles analysis of oxygen vacancy formation and migration in Sr2BMoO6 (B = Mg, Co, Ni)

RSC Advances ◽

10.1039/c6ra02297a ◽

2016 ◽

Vol 6 (38) ◽

pp. 31968-31975 ◽

Cited By ~ 9

Author(s):

Shuai Zhao ◽

Liguo Gao ◽

Chunfeng Lan ◽

Shyam S. Pandey ◽

Shuzi Hayase ◽

...

Keyword(s):

Density Functional Theory ◽

Oxygen Vacancy ◽

First Principles ◽

Density Functional ◽

Dft Method ◽

Double Perovskites ◽

Functional Theory ◽

Oxygen Vacancy Formation ◽

The Density Functional Theory ◽

And Migration

In this work, we present a detailed first-principles investigation on the stoichiometric and oxygen-deficient structures of double perovskites, Sr2BMoO6 (B = Mg, Co and Ni), using the density functional theory (DFT) method.

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Oxygen vacancy and doping atom effect on electronic structure and optical properties of Cd2SnO4

RSC Advances ◽

10.1039/c7ra10641f ◽

2018 ◽

Vol 8 (2) ◽

pp. 640-646 ◽

Cited By ~ 8

Author(s):

Mei Tang ◽

JiaXiang Shang ◽

Yue Zhang

Keyword(s):

Optical Properties ◽

Electronic Structure ◽

Oxygen Vacancy ◽

Density Functional ◽

Generalized Gradient ◽

Functional Theory ◽

The Density Functional Theory ◽

La Doped ◽

Doping Atom ◽

Atom Effect

The electronic structure and optical properties of oxygen vacancy and La-doped Cd2SnO4 were calculated using the plane-wave-based pseudopotential method based on the density functional theory (DFT) within the generalized gradient approximation (GGA).

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Structural and Electronic Properties of Oxygen Vacancies in Monoclinic HfO2

MRS Proceedings ◽

10.1557/proc-0996-h01-08 ◽

2007 ◽

Vol 996 ◽

Author(s):

Peter Broqvist ◽

Alfredo Pasquarello

Keyword(s):

Oxygen Vacancy ◽

Optical Absorption ◽

Total Energy ◽

Band Gap ◽

Electronic Properties ◽

Density Functional ◽

Oxygen Vacancies ◽

Structural And Electronic Properties ◽

Defect Levels ◽

Hybrid Density Functional

AbstractWe study structural and electronic properties of the oxygen vacancy in monoclinic HfO2 for five different charge states. We use a hybrid density functional to accurately reproduce the experimental band gap. To compare with measured defect levels, we determine total-energy differences appropriate to the considered experiments. Our results show that the oxygen vacancy can consistently account for the defect levels observed in optical absorption, direct electron injection, and trap-assisted conduction experiments.

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Theoretical Investigation of Energetic Salts with Pentazolate Anion

Molecules ◽

10.3390/molecules25081783 ◽

2020 ◽

Vol 25 (8) ◽

pp. 1783

Author(s):

Hao-Ran Wang ◽

Chong Zhang ◽

Bing-Cheng Hu ◽

Xue-Hai Ju

Keyword(s):

Density Functional ◽

Dft Method ◽

Functional Theory ◽

Calculated Density ◽

The Density Functional Theory ◽

Energetic Salts ◽

Vertical Electron Affinity ◽

The Difference ◽

Nitrogen Contents ◽

Experimental Density

Energetic salts based on pentazolate anion (cyclo-N5−) have attracted much attention due to their high nitrogen contents. However, it is an enormous challenge to efficiently screen out an appropriate cation that can match well with cyclo-N5−. The vertical electron affinity (VEA) of the cations and vertical ionization potential (VIP) of the anions for 135 energetic salts and some cyclo-N5− salts were calculated by the density functional theory (DFT). The magnitudes of VEA and VIP, and their matchability were analyzed. The results based on the calculations at the B3LYP/6-311++G(d,p) and B3LYP/aug-cc-pVTZ levels indicate that there is an excellent compatibility between cyclo-N5− and cation when the difference between the VEA of cation and the VIP of cyclo-N5− anion is −2.8 to −1.0 eV. The densities of the salts were predicted by the DFT method. Relationship between the calculated density and the experimental density was established as ρExpt = 1.111ρcal − 0.06067 with a correlation coefficient of 0.905. This regression equation could be in turn used to calibrate the calculated density of the cyclo-N5− energetic salts accurately. This work provides a favorable way to explore the energetic salts with excellent performance based on cyclo-N5−.

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Calculation of electronic structure and mechanical properties of DO3–Fe75-xSi25Nix intermetallic compounds by first principles

International Journal of Modern Physics B ◽

10.1142/s0217979215500873 ◽

2015 ◽

Vol 29 (13) ◽

pp. 1550087

Author(s):

R. Ma ◽

M. P. Wan ◽

J. Huang ◽

Q. Xie

Keyword(s):

Mechanical Properties ◽

Intermetallic Compounds ◽

First Principles ◽

Electronic Structures ◽

Density Functional ◽

Elastic Parameters ◽

Functional Theory ◽

Ni Content ◽

The Density Functional Theory ◽

The Difference

Based on the density functional theory (DFT), the plane-wave pseudopotential method was used to investigate the electronic structures and mechanical properties of DO 3– Fe 75-x Si 25 Ni x(x = 0, 3.125, 6.25 and 9.375) intermetallic compounds. The elastic parameters were calculated, and then the bulk modulus, shear modulus and elastic modulus were derived. The paper then focuses on the discussion of ductility and plasticity. The results show that by adding appropriate Ni to Fe 3 Si intermetallic compound can improve the ductility. But the hardness will increase when the Ni content exceeds 6.25%. Analysis of density of states (DOS) and overlap populations indicates that with the difference of the strength of bonding and activity, there were some differences of ductility among different Ni contents. The Fe 71.875 Ni 3.125 Si 25 has the lowest hardness because the covalent bonding (Fe–Si bond and Si–Ni bond) has the minimum covalent electrons.

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