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>

scholarly journals 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>

scholarly journals Interaction of CO with Gold in an Electrochemical Environment

2021 ◽  
Author(s):  
Sudarshan Vijay ◽  
Thomas Vagn Hogg ◽  
Johan Ehlers ◽  
Henrik Høgh Kristoffersen ◽  
Yu Katayama ◽  
...  
Keyword(s):  
Gas Phase ◽  
Co Adsorption ◽  
Underpotential Deposition ◽  
Attenuated Total Reflection ◽  
Adsorption Sites ◽  
Surface Enhanced ◽  
Adsorption Of Co ◽  
Dynamics Simulations ◽  
Explicit Water

<div> <div> <div> <p> </p><p>We present a joint theoretical-experimental study of CO coverage and facet selectivity on Au and under electrochemical conditions. With <i>in situ </i>attenuated total reflection surface enhanced IR spectroscopy (ATR-SEIRAS), we investigate the CO binding in an electrochemical environment. At 0.2V vs. SHE, we detect a CO band that disappears upon facet selective partial Pb underpotential deposition, suggesting that Pb blocks certain CO adsorption sites. With Pb underpotential deposition on single crystals and theoretical surface Pourbaix analysis, we eliminate (111) terraces as a possible adsorption site of CO. <i>Ab initio</i> molecular dynamics simulations of explicit water at the Au surface, 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<i> </i>than (211) steps in an electrochemical environment, even though Au steps in gas phase conditions bind CO* more strongly. The competition between water and adsorption can result in different binding sites for CO* on Au in gas phase and electrochemical environments. </p> <p>@font-face {font-family:"MS Mincho"; panose-1:2 2 6 9 4 2 5 8 3 4; mso-font-alt:"ＭＳ 明朝"; mso-font-charset:128; mso-generic-font-family:modern; mso-font-pitch:fixed; mso-font-signature:-536870145 1791491579 134217746 0 131231 0;}@font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:-536870145 1107305727 0 0 415 0;}@font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-469750017 -1073732485 9 0 511 0;}@font-face {font-family:"\@MS Mincho"; panose-1:2 2 6 9 4 2 5 8 3 4; mso-font-charset:128; mso-generic-font-family:modern; mso-font-pitch:fixed; mso-font-signature:-536870145 1791491579 134217746 0 131231 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin:0cm; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}.MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}div.WordSection1 {page:WordSection1;}</p> </div> </div> </div>

scholarly journals Stabilizing the Exotic Carbonic Acid by Bisulfate Ion

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 8
Author(s):  
Huili Lu ◽  
Shi-Wei Liu ◽  
Mengyang Li ◽  
Baocai Xu ◽  
Li Zhao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Density Functional ◽  
Carbonic Acid ◽  
Topological Analysis ◽  
Density Functional Theory Calculations ◽  
Ab Initio Molecular Dynamics ◽  
Important Species ◽  
Good Thermal Stability ◽  
Dynamics Simulations

Carbonic acid is an important species in a variety of fields and has long been regarded to be non-existing in isolated state, as it is thermodynamically favorable to decompose into water and carbon dioxide. In this work, we systematically studied a novel ionic complex [H2CO3·HSO4]− using density functional theory calculations, molecular dynamics simulations, and topological analysis to investigate if the exotic H2CO3 molecule could be stabilized by bisulfate ion, which is a ubiquitous ion in various environments. We found that bisulfate ion could efficiently stabilize all the three conformers of H2CO3 and reduce the energy differences of isomers with H2CO3 in three different conformations compared to the isolated H2CO3 molecule. Calculated isomerization pathways and ab initio molecular dynamics simulations suggest that all the optimized isomers of the complex have good thermal stability and could exist at finite temperatures. We also explored the hydrogen bonding properties in this interesting complex and simulated their harmonic infrared spectra to aid future infrared spectroscopic experiments. This work could be potentially important to understand the fate of carbonic acid in certain complex environments, such as in environments where both sulfuric acid (or rather bisulfate ion) and carbonic acid (or rather carbonic dioxide and water) exist.

scholarly journals Ion pair particles at the air–water interface

2017 ◽  
Vol 114 (47) ◽  
pp. 12401-12406 ◽  
Author(s):  
Manoj Kumar ◽  
Joseph S. Francisco
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Methanesulfonic Acid ◽  
Density Functional Theory Calculations ◽  
Particle Formation ◽  
Ion Pair ◽  
Urban Environments ◽  
Water Interface ◽  
Air Water Interface ◽  
Dynamics Simulations

Although the role of methanesulfonic acid (HMSA) in particle formation in the gas phase has been extensively studied, the details of the HMSA-induced ion pair particle formation at the air–water interface are yet to be examined. In this work, we have performed Born–Oppenheimer molecular dynamics simulations and density functional theory calculations to investigate the ion pair particle formation from HMSA and (R1)(R2)NH (for NH3, R1= R2= H; for CH3NH2, R1= H and R2= CH3; and for CH3NH2, R1= R2= CH3) at the air–water interface. The results show that, at the air–water interface, HMSA deprotonates within a few picoseconds and results in the formation of methanesulfonate ion (MSA−)⋅⋅H3O+ion pair. However, this ion pair decomposes immediately, explaining why HMSA and water alone are not sufficient for forming stable particles in atmosphere. Interestingly, the particle formation from the gas-phase hydrogen-bonded complexes of HMSA with (R1)(R2)NH on the water droplet is observed with a few femtoseconds, suggesting a mechanism for the gas to particle conversion in aqueous environments. The reaction involves a direct proton transfer between HMSA and (R1)(R2)NH, and the resulting MSA−⋅⋅(R1)(R2)NH2+complex is bound by one to four interfacial water molecules. The mechanistic insights gained from this study may serve as useful leads for understanding about the ion pair particle formation from other precursors in forested and polluted urban environments.

scholarly journals Solvation structure and dynamics of Li and LiO2 and their transformation in non-aqueous organic electrolyte solvents from first-principles simulations

2021 ◽  
Author(s):  
Behnaz Rahmani Didar ◽  
Axel Gross
Keyword(s):  
Gas Phase ◽  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Ionic Species ◽  
Ab Initio Molecular Dynamics ◽  
Functional Theory ◽  
Structure And Dynamics ◽  
O2 Reduction ◽  
The Impact

Density functional theory calculations together with ab initio molecular dynamics (AIMD) simulations have been used to study the solvation, diffusion and transformation of Li+ and LiO2 upon O2 reduction in three organic electrolytes. These processes are critical for the performance of Li-air batteries. Apart from studying the structure of the solvation shells in detail, AIMD simulations have been used to derive the diffusivity and together with the Blue Moon ensemble approach to explore LiO2 formation from Li+ and O2- and the subsequent disproportionation of 2LiO2 into Li2O2 + O2. By comparing the results of the simulations to gas phase calculations the impact of electrolytes on these reactions is assessed which turns out to be more pronounced for the ionic species involved in these reactions.

A New Phase of the Na+ Ion Conductor Na3PS4

2019 ◽  
Author(s):  
Theodosios Famprikis ◽  
James Dawson ◽  
François Fauth ◽  
Emmanuelle Suard ◽  
Benoit Fleutot ◽  
...  
Keyword(s):  
Solid Electrolytes ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Ion Conductor ◽  
Solid State Batteries ◽  
Density Analysis ◽  
Two Phases ◽  
Dynamics Simulations

<div> <p>Solid electrolytes are crucial for next‑generation solid‑state batteries and Na<sub>3</sub>PS<sub>4</sub> is one of the most promising Na<sup>+</sup> conductors for such applications. At present, two phases of Na<sub>3</sub>PS<sub>4</sub> have been identified and it had been thought to melt above 500 °C. In contrast, we show that it remains solid above this temperature and transforms into a third polymorph, γ, exhibiting superionic behavior. We propose an orthorhombic crystal structure for γ‑Na<sub>3</sub>PS<sub>4</sub> based on scattering density analysis of diffraction data and density functional theory calculations. We show that the Na<sup>+</sup> superionic behavior is associated with rotational motion of the thiophosphate polyanions pointing to a rotor phase, based on <i>ab initio</i> molecular dynamics simulations and supported by high‑temperature synchrotron and neutron diffraction, thermal analysis and impedance spectroscopy. These findings are of importance for the development of new polyanion‑based solid electrolytes.</p> </div>

Graphene adlayer growth between nonepitaxial graphene and Ni(111) substrate: a promising theoretical scheme

2020 ◽  
Author(s):  
Lijuan Meng ◽  
Jinlian Lu ◽  
Yujie Bai ◽  
Lili Liu ◽  
Tang Jingyi ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Chemical Vapor Deposition ◽  
Molecular Dynamics Simulations ◽  
Vapor Deposition ◽  
Density Functional ◽  
Chemical Vapor ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Dynamics Simulations

Understanding the fundamentals of chemical vapor deposition bilayer graphene growth is crucial for its synthesis. By employing density functional theory calculations and classical molecular dynamics simulations, we have investigated the...

scholarly journals Molecular Insights into Cage Occupancy of Hydrogen Hydrate: A Computational Study

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 699 ◽  
Author(s):  
Ma ◽  
Zhong ◽  
Liu ◽  
Zhong ◽  
Yan ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Storage ◽  
Molecular Dynamics Simulations ◽  
Density Functional ◽  
Storage Capacity ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Hydrogen Storage Capacity ◽  
Large Cage ◽  
Dynamics Simulations

Density functional theory calculations and molecular dynamics simulations were performed to investigate the hydrogen storage capacity in the sII hydrate. Calculation results show that the optimum hydrogen storage capacity is ~5.6 wt%, with the double occupancy in the small cage and quintuple occupancy in the large cage. Molecular dynamics simulations indicate that these multiple occupied hydrogen hydrates can occur at mild conditions, and their stability will be further enhanced by increasing the pressure or decreasing the temperature. Our work highlights that the hydrate is a promising material for storing hydrogen.

scholarly journals Solvent Effect on the Structure and Properties of RGD Peptide (1FUV) at Body Temperature (310 K) Using Ab Initio Molecular Dynamics

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3434
Author(s):  
Khagendra Baral ◽  
Puja Adhikari ◽  
Bahaa Jawad ◽  
Rudolf Podgornik ◽  
Wai-Yim Ching
Keyword(s):  
Molecular Dynamics ◽  
Body Temperature ◽  
Ab Initio ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Rgd Peptide ◽  
Ab Initio Molecular Dynamics ◽  
Quantum Mechanical ◽  
Aqueous Environment ◽  
Structure And Properties

The structure and properties of the arginine-glycine-aspartate (RGD) sequence of the 1FUV peptide at 0 K and body temperature (310 K) are systematically investigated in a dry and aqueous environment using more accurate ab initio molecular dynamics and density functional theory calculations. The fundamental properties, such as electronic structure, interatomic bonding, partial charge distribution, and dielectric response function at 0 and 310 K are analyzed, comparing them in dry and solvated models. These accurate microscopic parameters determined from highly reliable quantum mechanical calculations are useful to define the range and strength of complex molecular interactions occurring between the RGD peptide and the integrin receptor. The in-depth bonding picture analyzed using a novel quantum mechanical metric, the total bond order (TBO), quantifies the role played by hydrogen bonds in the internal cohesion of the simulated structures. The TBO at 310 K decreases in the dry model but increases in the solvated model. These differences are small but extremely important in the context of conditions prevalent in the human body and relevant for health issues. Our results provide a new level of understanding of the structure and properties of the 1FUV peptide and help in advancing the study of RGD containing other peptides.

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