scholarly journals Analysis of Preferred Mechanisms of CO Oxidation with Atomically Dispersed Pt1/TiO2 Using the Energetic Span Model

2021 ◽  
Author(s):  
Selin Bac ◽  
Shaama Mallikarjun Sharada
Keyword(s):  
Co Oxidation ◽  
Density Functional ◽  
Ab Initio Molecular Dynamics ◽  
Turnover Frequency ◽  
Mechanistic Studies ◽  
Functional Theory ◽  
Support Materials ◽  
Dispersed Catalysts ◽  
Co2 Desorption ◽  
Low Temperature Co Oxidation

This work examines the mechanisms of low-temperature CO oxidation with atomically dispersed Pt on rutile TiO2 (110) using density functional theory and the energetic span model (ESM). Of the 13 distinct pathways spanning Eley-Rideal (ER), termolecular ER (TER), Langmuir-Hinshelwood(LH), Mars-Van Krevelen (MvK) mechanisms as well as their combinations, TER with CO-assisted CO2 desorption yields the highest turnover frequency (TOF). However, this pathway is ruled out because Pt is dynamically unstable in an intermediate state in the TER cycle, determined in a prior ab initio molecular dynamics study by our group. We instead find that a previously neglected pathway – the ER mechanism – is the most plausible CO oxidation route based on agreement with experimental TOFs and turnover-determining states. The preferred mechanism is sensitive to temperature, with LH becoming more favorable than ER and TER above 750 K. By comparing TOFs for Pt1/TiO2 with prior mechanistic studies of various oxide-supported atomically dispersed catalysts in the literature, we also attempt to identify the most viable metal and support materials for CO oxidation.

Analysis of Preferred Mechanisms of CO Oxidation with Atomically Dispersed Pt1/TiO2 Using the Energetic Span Model

2021 ◽  
Author(s):  
Selin Bac ◽  
Shaama Mallikarjun Sharada
Keyword(s):  
Low Temperature ◽  
Co Oxidation ◽  
Density Functional ◽  
Co Adsorption ◽  
Ab Initio Molecular Dynamics ◽  
Functional Theory ◽  
Support Materials ◽  
Dispersed Catalysts ◽  
Active Metal ◽  
Low Temperature Co Oxidation

This work examines mechanisms of low-temperature CO oxidation over a single binding site of atomically dispersed Pt on rutile TiO2 (110) using density functional theory and the energetic span model (ESM). Of the 12 distinct pathways spanning Eley- Rideal (ER), termolecular ER (TER), Langmuir-Hinshelwood (LH), Mars-Van Krevelen (MvK) mechanisms as well as their combinations, TER with CO-assisted CO2 desorption yields the highest turnover frequency (TOF). However, this pathway is ruled out because Pt is dynamically unstable in an intermediate state in the TER cycle, determined in a prior ab initio molecular dynamics study by our group. We instead find, depending on reaction conditions, that either H1 is rendered inactive upon CO adsorption or the ER mechanism is preferred if O2 dissociatively adsorbs. ER exhibits the second highest TOF and the TOF-determining state is in qualitative agreement with experiment. TOFs for all MvK pathways are several orders of magnitude lower than ER and LH. By comparing TOFs for Pt1/TiO2 with prior mechanistic studies of various oxide-supported atomically dispersed catalysts in the literature, we identify the most active metal and support materials for low-temperature CO oxidation.

scholarly journals Ab initio molecular dynamics of hydrogen on tungsten surfaces

2021 ◽  
Author(s):  
Alberto Rodríguez-Fernández ◽  
Laurent Bonnet ◽  
Pascal Larrégaray ◽  
Ricardo Díez Muiño
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Molecular Dynamics ◽  
Dissociation Process ◽  
Functional Theory ◽  
Classical Molecular Dynamics ◽  
Hydrogen Molecules

The dissociation process of hydrogen molecules on W(110) was studied using density functional theory and classical molecular dynamics.

scholarly journals Pd/Pt embedded CN monolayers as efficient catalysts for CO oxidation

2019 ◽  
Vol 21 (46) ◽  
pp. 25743-25748
Author(s):  
Yong-Chao Rao ◽  
Xiang-Mei Duan
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Density Functional ◽  
Carbon Nitride ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Functional Theory ◽  
Spin Polarized ◽  
Planar Carbon

The catalytic performance of Pd/Pt embedded planar carbon nitride for CO oxidation has been investigated via spin-polarized density functional theory calculations.

The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation

2017 ◽  
Vol 19 (33) ◽  
pp. 22344-22354 ◽  
Author(s):  
Sajjad Ali ◽  
Tian Fu Liu ◽  
Zan Lian ◽  
Bo Li ◽  
Dang Sheng Su
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional Theory ◽  
Catalytic Activity ◽  
Carbon Nanotube ◽  
Reaction Mechanism ◽  
Co Oxidation ◽  
Density Functional ◽  
Functional Theory ◽  
Single Walled Carbon Nanotube ◽  
Wales Defect

The mechanism of CO oxidation by O2 on a single Au atom supported on pristine, mono atom vacancy (m), di atom vacancy (di) and the Stone Wales defect (SW) on single walled carbon nanotube (SWCNT) surface is systematically investigated theoretically using density functional theory.

scholarly journals Unexpectedly Large Couplings Between Orthogonal Units in Anthraquinone Polymers

2019 ◽  
Author(s):  
Rocco Peter Fornari ◽  
Piotr de Silva
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Lone Pair ◽  
Localized States ◽  
Ab Initio Molecular Dynamics ◽  
Coupling Mechanism ◽  
Functional Theory ◽  
Pi Interactions

Directly linked polyanthraquinones have relatively large electronic couplings between charge-localized states despite near-orthogonality of the monomer units. By using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations, we investigate this unusual coupling mechanism and show that this is due to strong lone pair-pi interactions, which are maximized around orthogonal conformations. We find that such materials are largely resilient to dynamic disorder and are promising for organic electronics applications.

Cu dimer anchored on C2N monolayer: low-cost and efficient Bi-atom catalyst for CO oxidation

Nanoscale ◽  
2018 ◽  
Vol 10 (33) ◽  
pp. 15696-15705 ◽  
Author(s):  
Fengyu Li ◽  
Zhongfang Chen
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Density Functional ◽  
Low Cost ◽  
Functional Theory ◽  
Dft Computations

By means of density functional theory (DFT) computations, we systemically investigated CO/O2 adsorption and CO oxidation pathways on a bi-atom catalyst, namely, a copper dimer anchored on a C2N monolayer (Cu2@C2N), and we compared it with its monometallic counterpart Cu1@C2N.

Ti and Zr Transition Metals Effect in the D03 Fe3Al by Ab Initio Study Approach

2014 ◽  
Vol 783-786 ◽  
pp. 1640-1645
Author(s):  
Jean Marc Raulot ◽  
S. Chentouf ◽  
T. Grosdidier ◽  
Hafid Aourag
Keyword(s):  
Molecular Dynamics ◽  
Transition Metals ◽  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Molecular Dynamics ◽  
Effect Of Temperature ◽  
Site Preference ◽  
Functional Theory ◽  
Study Approach

The effect of the Ti and Zr transition metals on the D03-Fe3Al intermetallic compounds has been investigated by means of ab initio Pseudo Potentials numerical simulations based on Density Functional Theory. Two main issues will be addressed the understanding of the role of these two transition metals in terms of stability of the bulk at the light of their site preference in the D03-Fe3Al structure the behaviour of Ti and Zr transition metals in the sigma 5 (310) [001] grain boundary and their effect on the structural stability of this interface. An important issue when studying these aspects is to take into accounts the effect of temperature. This requires a molecular dynamics treatment of the atoms in the supercell. The technique known as ab initio molecular dynamics (AIMD) solves these problems by combining ‘on the fly’ electronic structure calculations with finite temperature dynamics. Thus, our study was conducted both using the conventional static ab initio calculations (0K) as well as by taking into account the effect of temperature (Ab Initio Molecular Dynamics).

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