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Zhang Q, Guo L, Hao Z. Exploration of high-performance W 6 S 8 -supported single-atom Rh 1 catalysts for reverse water–gas shift reaction and methanol formation via DFT computational study. Polyhedron 2018. [DOI: 10.1016/j.poly.2018.01.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Rodriguez JA, Liu P, Takahashi Y, Nakamura K, Viñes F, Illas F. Desulfurization Reactions on Surfaces of Metal Carbides: Photoemission and Density–Functional Studies. Top Catal 2010. [DOI: 10.1007/s11244-010-9452-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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4
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Clayborne PA, Jones CE, Gupta U, Melko JJ, Khanna SN, Castleman AW. Structural evolution of triniobium carbide clusters: evidence of large Cn chains (n = 3-4) in Nb3Cn- (n = 5-10) clusters. J Phys Chem A 2010; 114:1290-7. [PMID: 19673506 DOI: 10.1021/jp905022p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
First-principle density functional calculations and photoelectron spectroscopy experiments show that triniobium carbide clusters exist in multiple motifs. The Nb(3)C(n)(-) (n = 5-10) series have isomers surrounding a triangular Nb(3) base while incorporating Nb-C bonding. We provide evidence of not only C(2) carbon chains but also stable isomers with previously unidentified C(3) and C(4) carbon chains in triniobium carbide clusters.
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Affiliation(s)
- Peneé A Clayborne
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000, USA
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Liu P, Choi Y, Yang Y, White MG. Methanol Synthesis from H2 and CO2 on a Mo6S8 Cluster: A Density Functional Study. J Phys Chem A 2009; 114:3888-95. [DOI: 10.1021/jp906780a] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Ping Liu
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, and Department of Chemistry, State University of New York (SUNY) Stony Brook, Stony Brook, New York 11794
| | - YongMan Choi
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, and Department of Chemistry, State University of New York (SUNY) Stony Brook, Stony Brook, New York 11794
| | - Yixiong Yang
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, and Department of Chemistry, State University of New York (SUNY) Stony Brook, Stony Brook, New York 11794
| | - Michael G. White
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, and Department of Chemistry, State University of New York (SUNY) Stony Brook, Stony Brook, New York 11794
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Ticknor BW, Bandyopadhyay B, Duncan MA. Photodissociation of Noble Metal-Doped Carbon Clusters. J Phys Chem A 2008; 112:12355-66. [DOI: 10.1021/jp807867r] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- B. W. Ticknor
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
| | - B. Bandyopadhyay
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
| | - M. A. Duncan
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
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Viñes F, Rodriguez JA, Liu P, Illas F. Catalyst size matters: Tuning the molecular mechanism of the water–gas shift reaction on titanium carbide based compounds. J Catal 2008. [DOI: 10.1016/j.jcat.2008.09.011] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Reed ZD, Duncan MA. Photodissociation of Yttrium and Lanthanum Oxide Cluster Cations. J Phys Chem A 2008; 112:5354-62. [DOI: 10.1021/jp800588r] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Z. D. Reed
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
| | - M. A. Duncan
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
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Molek KS, Anfuso-Cleary C, Duncan MA. Photodissociation of Iron Oxide Cluster Cations. J Phys Chem A 2008; 112:9238-47. [DOI: 10.1021/jp8009436] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- K. S. Molek
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
| | - C. Anfuso-Cleary
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
| | - M. A. Duncan
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556
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Liu P, Rodriguez JA. Water-gas-shift reaction on molybdenum carbide surfaces: essential role of the oxycarbide. J Phys Chem B 2007; 110:19418-25. [PMID: 17004800 DOI: 10.1021/jp0621629] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Density functional theory (DFT) was employed to investigate the behavior of Mo carbides in the water-gas-shift reaction (WGS, CO + H(2)O --> H(2) +CO(2)). The kinetics of the WGS reaction was studied on the surfaces of Mo-terminated Mo(2)C(001) (Mo-Mo(2)C), C-terminated Mo(2)C(001) (C-Mo(2)C), and Cu(111) as a known active catalyst. Our results show that the WGS activity decreases in a sequence: Cu > C-Mo(2)C > Mo-Mo(2)C. The slow kinetics on C-Mo(2)C and Mo-Mo(2)C is due to the fact that the C or Mo sites bond oxygen too strongly to allow the facile removal of this species. In fact, due to the strong O-Mo and O-C interactions, the carbide surfaces are likely to be covered by O produced from the H(2)O dissociation. It is shown that the O-covered Mo-terminated Mo(2)C(001) (O_Mo-Mo(2)C) surface displays the lowest WGS activity of all. With the Mo oxide in the surface, O_Mo-Mo(2)C is too inert to adsorb CO or to dissociate H(2)O. In contrast, the same amount of O on the C-Mo(2)C surface (O_C-Mo(2)C) does not lead to deactivation, but enhances the rate of the WGS reaction and makes this system even more active than Cu. The good behavior of O_C-Mo(2)C is attributed to the formation of a Mo oxycarbide in the surface. The C atoms destabilize O-poisoning by forming CO species, which shift away from the Mo hollow sites when the surface reacts with other adsorbates. In this way, the Mo sites are able to provide a moderate bond to the reaction intermediates. In addition, both C and O atoms are not spectators and directly participate in the WGS reaction.
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Affiliation(s)
- Ping Liu
- Department of Chemistry, Brookhaven National Laboratory, Bldg. 555, Upton, New York 11973, USA.
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Molek KS, Reed ZD, Ricks AM, Duncan MA. Photodissociation of Chromium Oxide Cluster Cations. J Phys Chem A 2007; 111:8080-9. [PMID: 17665887 DOI: 10.1021/jp073789+] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chromium oxide cluster cations, Cr(n)O(m)+, are produced by laser vaporization in a pulsed nozzle cluster source and detected with time-of-flight mass spectrometry. The mass spectrum exhibits a limited number of stoichiometries for each value of n, where m > n. The cluster cations are mass selected and photodissociated using the second (532 nm) or third (355 nm) harmonic output of a Nd:YAG laser. At either wavelength, multiphoton absorption is required to dissociate these clusters, which is consistent with their expected strong bonding. Cluster dissociation occurs via elimination of molecular oxygen, or by fission processes producing stable cation species and/or eliminating stable neutrals such as CrO3, Cr(2)O(5), or Cr(4)O(10). Specific cation clusters identified to be stable because they are produced repeatedly in the decomposition of larger clusters include Cr(2)O(4)+, Cr(3)O(6)+, Cr(3)O(7)+, Cr(4)O(9)+, and Cr(4)O(10)+.
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Affiliation(s)
- K S Molek
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA
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Wen XD, Cao Z, Li YW, Wang J, Jiao H. Structure and Energy of Mo27SxCy Clusters: A Density Functional Theory Study. J Phys Chem B 2006; 110:23860-9. [PMID: 17125352 DOI: 10.1021/jp063323b] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
For understanding the carburization processes of MoSx catalysts, the structures and energies of Mo27SxCy cluster models have been computed at the level of density functional theory. The surface sulfur atoms on the Mo edge and S edge as well as bulky sulfur atoms have been replaced by atomic carbon, and the corresponding structures have S/C ratios in the range of 0.8-55. The formation of all Mo27SxCy structures is favored thermodynamically. It is also found that the formation of CS and C2 bridging units is more favored than the individual or separated replacements and that the formation of C2 bridging units is more favored than that of CS units. In contrast, the replacement of sulfur on the Mo edge is least favored. Furthermore, the replacement of the bulky sulfur on the Mo edge is equally favored as those of sulfur on the S edge. For aiding further experimental studies, the C=S and C=C stretching frequencies have been computed.
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Affiliation(s)
- Xiao-Dong Wen
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi 030001, People's Republic of China
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Liu P, Lightstone JM, Patterson MJ, Rodriguez JA, Muckerman JT, White MG. Gas-phase Interaction of Thiophene with the Ti8C12+ and Ti8C12 Met-Car Clusters. J Phys Chem B 2006; 110:7449-55. [PMID: 16599524 DOI: 10.1021/jp060340s] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reactivity of the Ti(8)C(12)(+) met-car cation toward thiophene was investigated using density functional theory (DFT) and mass selective ion chemistry. It is shown that the experimentally observed mass spectrum can be well described by the DFT calculations. In contrast to the weak bonding interactions seen for thiophene on a TiC(001) surface, the Ti(8)C(12)(+) met-car cation is able to interact strongly with up to four thiophene molecules with the cluster staying intact. In the most stable conformation, the thiophene molecules bond to the four low-coordinated Ti(0) sites of Ti(8)C(12)(+) via a eta(5)-C,S coordination. The stability and the activity of the Ti(8)C(12)(+) met-car is observed to increase with an increasing number of attached thiophene molecules at the Ti(0) sites, which is associated with a significant transfer of electron density from thiophene to the cluster. The additional electron density on the Ti(8)C(12)(+) cation cluster, however, is not sufficient to cleave the C-S bonds of thiophene and the dissociation reaction of thiophene is predicted to be a highly activated process. By contrast, DFT calculations for the neutral Ti(8)C(12) met-car predict that the dissociation reaction leading to adsorbed S and C(4)H(4) fragments is energetically favorable for the first thiophene molecule. The binding behavior for subsequent addition of thiophene molecules to the neutral met-car is also presented and compared to that of the cation.
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Affiliation(s)
- Ping Liu
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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Lightstone JM, Patterson MJ, Liu P, White MG. Gas-Phase Reactivity of the Ti8C12+ Met-car with Triatomic Sulfur-Containing Molecules: CS2, SCO, and SO2. J Phys Chem A 2006; 110:3505-13. [PMID: 16526629 DOI: 10.1021/jp057277b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gas-phase Ti(x)C(y)+ clusters (x/y = 3/5, 4/7, 5/9, 6/9, 7/12, 8/12, 9/12) including the magic Ti8C12+ (met-car) have been produced by reactive sputtering with a magnetron cluster source. The gas-phase reactivity of the met-car with SCO, CS2, and SO2 was investigated in a hexapole collision cell by way of tandem mass spectrometry. Results indicate an increase in activity as the oxygen-to-sulfur ratio increases (SO2 > SCO > CS2) with products ranging from association to break down of the met-car cluster. Trends in the mass spectra also indicate SCO and CS2 may bond to the met-car in a unique way not observed in previous reactivity studies on Ti8C12+. To investigate this, several possible single molecule-cluster bonding configurations were calculated with density functional theory. The results indicate that bridge bonding of the intact molecules is energetically preferred. In addition, the energy barriers and transition states leading to dissociation products were calculated and the trends are found to be in qualitative agreement with experiment. The effects of the different types of bonding and number of adsorbed species on the reactivity of the met-car along with proposed reaction mechanisms for product formation are also discussed.
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Affiliation(s)
- James M Lightstone
- Department of Chemistry, SUNY Stony Brook, Stony Brook, New York 11794, USA
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Sulfur adsorption and sulfidation of transition metal carbides as hydrotreating catalysts. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.molcata.2005.06.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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