scholarly journals Automated Detection and Characterization of Surface Restructuring Events in Bimetallic Catalysts

2019 ◽  
Author(s):  
Jin Soo Lim ◽  
Nicola Molinari ◽  
Kaining Duanmu ◽  
Philippe Sautet ◽  
Boris Kozinsky
Keyword(s):  
Bimetallic Catalysts ◽  
Density Functional ◽  
Surface Segregation ◽  
Surface Restructuring ◽  
Bimetallic Systems ◽  
Automated Method ◽  
Elementary Surface ◽  
Systematic Understanding ◽  
Interlayer Exchange

<div>Surface restructuring in bimetallic systems has recently been shown to play a crucial role in heterogeneous catalysis. In particular, the segregation in binary alloys can be reversed in the presence of strongly bound adsorbates. Mechanistic characterization of such restructuring phenomena at the atomic level remains scarce and challenging due to the large configurational space that must be explored. To this end, we propose an automated method to discover elementary surface restructuring processes in an unbiased fashion, using Pd/Ag as an example. We employ high-temperature classical molecular dynamics (MD) to rapidly detect restructuring events, isolate them, and optimize using density functional theory (DFT). In addition to confirming the known exchange descent mechanism, our systematic approach has revealed three new predominant classes of events at step edges of close-packed surfaces that have not been considered before: (1) vacancy insertion; (2) direct exchange; (3) interlayer exchange. The discovered events enable us to construct the complete set of mechanistic pathways by which Pd is incorporated into the Ag host in vacuum. These atomistic insights provide a step toward systematic understanding and engineering of surface segregation dynamics in bimetallic catalysts.</div>

scholarly journals Automated Detection and Characterization of Surface Restructuring Events in Bimetallic Catalysts

2019 ◽  
Author(s):  
Jin Soo Lim ◽  
Nicola Molinari ◽  
Kaining Duanmu ◽  
Philippe Sautet ◽  
Boris Kozinsky
Keyword(s):  
Bimetallic Catalysts ◽  
Density Functional ◽  
Surface Segregation ◽  
Surface Restructuring ◽  
Bimetallic Systems ◽  
Automated Method ◽  
Elementary Surface ◽  
Systematic Understanding ◽  
Interlayer Exchange

<div>Surface restructuring in bimetallic systems has recently been shown to play a crucial role in heterogeneous catalysis. In particular, the segregation in binary alloys can be reversed in the presence of strongly bound adsorbates. Mechanistic characterization of such restructuring phenomena at the atomic level remains scarce and challenging due to the large configurational space that must be explored. To this end, we propose an automated method to discover elementary surface restructuring processes in an unbiased fashion, using Pd/Ag as an example. We employ high-temperature classical molecular dynamics (MD) to rapidly detect restructuring events, isolate them, and optimize using density functional theory (DFT). In addition to confirming the known exchange descent mechanism, our systematic approach has revealed three new predominant classes of events at step edges of close-packed surfaces that have not been considered before: (1) vacancy insertion; (2) direct exchange; (3) interlayer exchange. The discovered events enable us to construct the complete set of mechanistic pathways by which Pd is incorporated into the Ag host in vacuum. These atomistic insights provide a step toward systematic understanding and engineering of surface segregation dynamics in bimetallic catalysts.</div>

scholarly journals Machine Learning Prediction of Surface Segregation Energies on Low Index Bimetallic Surfaces

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2182
Author(s):  
Damilola Ologunagba ◽  
Shyam Kattel
Keyword(s):  
Machine Learning ◽  
Dft Calculations ◽  
Bimetallic Catalysts ◽  
Density Functional ◽  
Surface Segregation ◽  
Surface Composition ◽  
Bulk Composition ◽  
Statistical Machine Learning ◽  
Bimetallic Surfaces ◽  
Computing Platforms

Surface chemical composition of bimetallic catalysts can differ from the bulk composition because of the segregation of the alloy components. Thus, it is very useful to know how the different components are arranged on the surface of catalysts to gain a fundamental understanding of the catalysis occurring on bimetallic surfaces. First-principles density functional theory (DFT) calculations can provide deeper insight into the surface segregation behavior and help understand the surface composition on bimetallic surfaces. However, the DFT calculations are computationally demanding and require large computing platforms. In this regard, statistical/machine learning methods provide a quick and alternative approach to study materials properties. Here, we trained previously reported surface segregation energies on low index surfaces of bimetallic catalysts using various linear and non-linear statistical methods to find a correlation between surface segregation energies and elemental properties. The results revealed that the surface segregation energies on low index bimetallic surfaces can be predicted using fundamental elemental properties.

scholarly journals Automated Detection and Characterization of Surface Restructuring Events in Bimetallic Catalysts

2019 ◽  
Vol 123 (26) ◽  
pp. 16332-16344 ◽  
Author(s):  
Jin Soo Lim ◽  
Nicola Molinari ◽  
Kaining Duanmu ◽  
Philippe Sautet ◽  
Boris Kozinsky
Keyword(s):  
Bimetallic Catalysts ◽  
Automated Detection ◽  
Surface Restructuring

scholarly journals A New Piano-Stool Ruthenium(II) P-Cymene-Based Complex: Crystallographic, Hirshfeld Surface, DFT, and Luminescent Studies

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Mohd. Muddassir ◽  
Abdullah Alarifi ◽  
Mohd. Afzal
Keyword(s):  
Density Functional ◽  
Weak Interactions ◽  
Energy Levels ◽  
Hirshfeld Surface ◽  
Binding Energies ◽  
Orbital Energy ◽  
Aminosalicylic Acid ◽  
Full Characterization

A new complex (Ru(η6-p-cymene)(5-ASA)Cl2) (1) where 5-ASA is 5-aminosalicylic acid has been prepared by reacting the ruthenium arene precursors ((η6-arene)Ru(μ-Cl)Cl)2, with the 5-ASA ligands in a 1:1 ratio. Full characterization of complex 1 was accomplished by elemental analysis, IR, and TGA following the structure obtained from a single-crystal X-ray pattern. The structural analysis revealed that complex 1 shows a “piano-stool” geometry with Ru-C (2.160(5)- 2.208(5)Å), Ru-N (2.159(4) Å) distances, which is similar to equivalents sister complex. Density functional theory (DFT) was used to calculate the significant molecular orbital energy levels, binding energies, bond angles, bond lengths, and spectral data (FTIR, NMR, and UV–VIS) of complex 1, consistent with the experimental results. The IR and UV–VIS spectra of complex 1 were computed using all of the methods and choose the most appropriate way to discuss. Hirshfeld surface analysis was also executed to understand the role of weak interactions such as H⋯H, C⋯H, C-H⋯π, and vdW interactions, which play a significant role in the crystal environment’s stability. Moreover, the luminescence results at room temperature show that complex 1 gives a more intense emission band positioned at 465 nm upon excitation at 330 nm makes it a suitable candidate for the building of photoluminescent material.

scholarly journals Structural and computational investigation of an imine-based propeller-shaped macrocyclic cage

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Sriram Srinivasa Raghvan ◽  
Suresh Madhu ◽  
Velmurugan Devadasan ◽  
Gunasekaran Krishnasamy
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Strain Tensor ◽  
Strong Interactions ◽  
Soft Condensed Matter ◽  
Functional Theory ◽  
Self Assembling ◽  
Phenyl Rings ◽  
Crystal Volume

AbstractIn this study, we present the synthesis, spectroscopic and structural characterization of self-assembling gem-dimethyl imine based molecular cage (IMC). Self-assembling macrocycles and cages have well-defined cavities and have extensive functionalities ranging from energy storage, liquid crystals, and catalysts to water splitting photo absorber. IMC has large voids i.e., 25% of the total crystal volume thus could accommodate wide substrates. The synthesized imine-based molecular cages are stabilized by coaxial π bonded networks and long-range periodic van der Waal and non-bonded contacts as observed from the crystal structure. IMC also has typical properties of soft condensed matter materials, hence theoretical prediction of stress and strain tensor along with thermophysical properties were computed on crystal system and were found to be stable. Molecular dynamics revealed IMC is stabilized by, strong interactions between the interstitial phenyl rings. Density functional theory (DFT) based physicochemical properties were evaluated and has band gap of around 2.38ev (520 nm) similar to various photocatalytic band gap materials.

scholarly journals Combined Macroscopic, Nanoscopic, and Atomic-Scale Characterization of Gold-Ruthenium Bimetallic Catalysts for Octanol Oxidation

2016 ◽  
Vol 33 (7) ◽  
pp. 419-437 ◽  
Author(s):  
Lidia E. Chinchilla ◽  
Carol Olmos ◽  
Mert Kurttepeli ◽  
Sara Bals ◽  
Gustaaf Van Tendeloo ◽  
...  
Keyword(s):  
Bimetallic Catalysts ◽  
Atomic Scale ◽  
Scale Characterization

scholarly journals Metal-Rich Metallaboranes: Synthesis, Structures and Bonding of Bi- and Trimetallic Open-Faced Cobaltaboranes

Inorganics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 28
Author(s):  
Kriti Pathak ◽  
Chandan Nandi ◽  
Jean-François Halet ◽  
Sundargopal Ghosh
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Room Temperature ◽  
Electron Pair ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Cluster 2 ◽  
Cobalt Center

Synthesis, isolation, and structural characterization of unique metal rich diamagnetic cobaltaborane clusters are reported. They were obtained from reactions of monoborane as well as modified borohydride reagents with cobalt sources. For example, the reaction of [Cp*CoCl]2 with [LiBH4·THF] and subsequent photolysis with excess [BH3·THF] (THF = tetrahydrofuran) at room temperature afforded the 11-vertex tricobaltaborane nido-[(Cp*Co)3B8H10] (1, Cp* = η5-C5Me5). The reaction of Li[BH2S3] with the dicobaltaoctaborane(12) [(Cp*Co)2B6H10] yielded the 10-vertex nido-2,4-[(Cp*Co)2B8H12] cluster (2), extending the library of dicobaltadecaborane(14) analogues. Although cluster 1 adopts a classical 11-vertex-nido-geometry with one cobalt center and four boron atoms forming the open pentagonal face, it disobeys the Polyhedral Skeletal Electron Pair Theory (PSEPT). Compound 2 adopts a perfectly symmetrical 10-vertex-nido framework with a plane of symmetry bisecting the basal boron plane resulting in two {CoB3} units bridged at the base by two boron atoms and possesses the expected electron count. Both compounds were characterized in solution by multinuclear NMR and IR spectroscopies and by mass spectrometry. Single-crystal X-ray diffraction analyses confirmed the structures of the compounds. Additionally, density functional theory (DFT) calculations were performed in order to study and interpret the nature of bonding and electronic structures of these complexes.

scholarly journals Synthesis and Characterization of the Germathioacid Chloride Coordinated by an N-Heterocyclic Carbene §

Inorganics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 76 ◽  
Author(s):  
Yasunobu Egawa ◽  
Chihiro Fukumoto ◽  
Koichiro Mikami ◽  
Nobuhiro Takeda ◽  
Masafumi Unno
Keyword(s):  
Carboxylic Acid ◽  
Density Functional ◽  
Dft Calculation ◽  
Acid Chlorides ◽  
Carboxylic Acid Chloride ◽  
Functional Theory ◽  
Nitrogen Ligands ◽  
Bond Property ◽  
Nitrogen Bonds

Carboxylic acid chlorides are useful substrates in organic chemistry. Many germanium analogues of carboxylic acid chloride have been synthesized so far. Nevertheless, all of the reported germathioacid chlorides use bidentate nitrogen ligands and contain germanium-nitrogen bonds. Our group synthesized germathioacid chloride, Ge(S)Cl{C6H3-2,6-Tip2}(Im-i-Pr2Me2), using N-heterocyclic carbene (Im-i-Pr2Me2). As a result of density functional theory (DFT) calculation, it was found that electrons are localized on sulfur, and the germanium-sulfur bond is a single bond with a slight double bond property.

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