scholarly journals Density functional modeling and total scattering analysis of the atomic structure of a quaternary CaO−MgO−Al2O3−SiO2 (CMAS) glass: Uncovering the local environment of calcium and magnesium

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Kai Gong ◽  
V. Ongun Özçelik ◽  
Kengran Yang ◽  
Claire E. White
Keyword(s):  
Atomic Structure ◽  
Density Functional ◽  
Local Environment ◽  
Functional Modeling ◽  
Total Scattering ◽  
Calcium And Magnesium

Nanometer Scale Spectroscopic Visualization of Catalytic Sites During a Hydrogenation Reaction on a Pd/Au Bimetallic Catalyst

2020 ◽  
Author(s):  
hao yin ◽  
Liqing Zheng ◽  
Wei Fang ◽  
Yin-Hung Lai ◽  
Nikolaus Porenta ◽  
...  
Keyword(s):  
Catalytic Hydrogenation ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Bimetallic Catalyst ◽  
Local Environment ◽  
Hydrogenation Reaction ◽  
Boundary Density ◽  
Catalytic Sites ◽  
Powerful Analytical Tool ◽  
Tip Enhanced Raman Spectroscopy

<p>Understanding the mechanism of catalytic hydrogenation at the local environment requires chemical and topographic information involving catalytic sites, active hydrogen species and their spatial distribution. Here, tip-enhanced Raman spectroscopy (TERS) was employed to study the catalytic hydrogenation of chloro-nitrobenzenethiol on a well-defined Pd(sub-monolayer)/Au(111) bimetallic catalyst (<i>p</i><sub>H2</sub>=1.5 bar, 298 K), where the surface topography and chemical fingerprint information were simultaneously mapped with nanoscale resolution (≈10 nm). TERS imaging of the surface after catalytic hydrogenation confirms that the reaction occurs beyond the location of Pd sites. The results demonstrate that hydrogen spillover accelerates hydrogenation at the Au sites within 20 nm from the bimetallic Pd/Au boundary. Density functional theory was used to elucidate the thermodynamics of interfacial hydrogen transfer. We demonstrate that TERS as a powerful analytical tool provides a unique approach to spatially investigate the local structure-reactivity relationship in catalysis.</p>

Nanometer Scale Spectroscopic Visualization of Catalytic Sites During a Hydrogenation Reaction on a Pd/Au Bimetallic Catalyst

2020 ◽  
Author(s):  
Hao Yin ◽  
Liqing Zheng ◽  
Wei Fang ◽  
Yin-Hung Lai ◽  
Nikolaus Porenta ◽  
...  
Keyword(s):  
Catalytic Hydrogenation ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Bimetallic Catalyst ◽  
Local Environment ◽  
Hydrogenation Reaction ◽  
Boundary Density ◽  
Catalytic Sites ◽  
Powerful Analytical Tool ◽  
Tip Enhanced Raman Spectroscopy

<p>Understanding the mechanism of catalytic hydrogenation at the local environment requires chemical and topographic information involving catalytic sites, active hydrogen species and their spatial distribution. Here, tip-enhanced Raman spectroscopy (TERS) was employed to study the catalytic hydrogenation of chloro-nitrobenzenethiol on a well-defined Pd(sub-monolayer)/Au(111) bimetallic catalyst (<i>p</i><sub>H2</sub>=1.5 bar, 298 K), where the surface topography and chemical fingerprint information were simultaneously mapped with nanoscale resolution (≈10 nm). TERS imaging of the surface after catalytic hydrogenation confirms that the reaction occurs beyond the location of Pd sites. The results demonstrate that hydrogen spillover accelerates hydrogenation at the Au sites within 20 nm from the bimetallic Pd/Au boundary. Density functional theory was used to elucidate the thermodynamics of interfacial hydrogen transfer. We demonstrate that TERS as a powerful analytical tool provides a unique approach to spatially investigate the local structure-reactivity relationship in catalysis.</p>

scholarly journals Density functional theory study on the atomic structure and electronic states of Cu(100) (2×22)R45°-O surface

2005 ◽  
Vol 54 (11) ◽  
pp. 5350
Author(s):  
Cai Jian-Qiu ◽  
Tao Xiang-Ming ◽  
Chen Wen-Bin ◽  
Zhao Xin-Xin ◽  
Tan Ming-Qiu
Keyword(s):  
Density Functional Theory ◽  
Atomic Structure ◽  
Density Functional ◽  
Electronic States ◽  
Density Functional Theory Study ◽  
Functional Theory

scholarly journals Atomic Structure-free Representation of Active Motifs for Expedited Catalyst Discovery

2021 ◽  
Author(s):  
Dong Hyeon Mok ◽  
Seoin Back
Keyword(s):  
Atomic Structure ◽  
Density Functional ◽  
Nearest Neighbor ◽  
Catalyst Surface ◽  
Binding Energies ◽  
Reasonable Accuracy ◽  
Density Functional Calculation ◽  
Energy Prediction ◽  
Binding Energy Prediction ◽  
Free Representation

For CO* and H* binding energy prediction, we develop new representation of catalyst surface which split surface into three types of site, first nearest neighbor of adsorbates and second nearest neighbor in same layer and sublayer. From this representation and machine learning regression model, we achieve reasonable accuracy (0.120 eV for CO* and 0.105 eV for H*) with quick training (~200 sec using CPU). Because our representation does not require density functional calculation and atomic structure modelling, it can predict binding energies of possible active motifs without time-consuming steps.

scholarly journals The atomic structure of a MgCo2O4 nanoparticle for a positive electrode of a Mg rechargeable battery

2019 ◽  
Vol 55 (17) ◽  
pp. 2517-2520 ◽  
Author(s):  
Naoto Kitamura ◽  
Yuhei Tanabe ◽  
Naoya Ishida ◽  
Yasushi Idemoto
Keyword(s):  
Monte Carlo ◽  
Atomic Structure ◽  
Positive Electrode ◽  
Scattering Data ◽  
Rechargeable Battery ◽  
Reverse Monte Carlo ◽  
Spinel Type ◽  
Total Scattering ◽  
X Ray ◽  
Neutron Total Scattering

The atomic structure of a spinel-type MgCo2O4 nanoparticle was investigated by the reverse Monte Carlo modelling using X-ray and neutron total scattering data.

scholarly journals Short-Range Structure of Ti0.63V0.27Fe0.10D1.73 from Neutron Total Scattering and Reverse Monte Carlo Modelling

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1947
Author(s):  
Henrik Mauroy ◽  
Konstantin Klyukin ◽  
Marina G. Shelyapina ◽  
David A. Keen ◽  
Annett Thøgersen ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Hydrogen Storage ◽  
Short Range ◽  
Density Functional ◽  
Metal Species ◽  
Face Centered Cubic ◽  
Reverse Monte Carlo ◽  
Hydrogen Atoms ◽  
Total Scattering ◽  
Neutron Total Scattering

Ti-V-based body-centered cubic (BCC) alloys have potential for large-scale hydrogen storage if expensive vanadium is substituted with much cheaper Fe-containing ferrovanadium. Use of ferrovanadium reduces the alloys’ hydrogen storage capacity. This is puzzling since the amount of Fe is low and hydrogen atoms are accommodated in interstitial sites which are partly coordinated by Fe in many intermetallic compounds. The present work is aimed at finding a structural explanation for Fe-induced capacity loss in Ti-V alloys. Since such alloys and their hydrides are highly disordered without long-range occupational order of the different metal species, it was necessary to employ a technique which is sensitive to local structure. Neutron total scattering coupled with reverse Monte Carlo modelling was thus employed to elucidate short-range atomic correlations in Ti0.63V0.27Fe0.10D1.73 from the pair distribution function. It was found that Fe atoms form clusters and that the majority of the vacant interstitial sites are within these clusters. These clusters take the same face-centered cubic structure as the Ti-V matrix in the deuteride and thus they are not simply unreacted Fe which has a BCC structure. The presence of Fe clusters is confirmed by transmission electron microscopy. Density functional theory calculations indicate that the clustering is driven by thermodynamics.

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