The electronic structure of MoC and WC by anion photoelectron spectroscopy

Li, Xi; Liu, Sherry S.; Chen, Wenwu; Wang, Lai-Sheng

doi:10.1063/1.479523

Cited by 41 publications

(14 citation statements)

References 15 publications

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“…Transition metal carbides have a long and rich history of experimental and theoretical studies. − A possible motivation for these studies is that the transition metal catalysts find extensive use in reforming petroleum-based products. Thus, there is a compelling need to comprehend the nature of metal−carbon bonds, as this could aid in the understanding of catalytic selectivity and mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Electronic Structures of Niobium Carbides: NbC_n (n = 3−8)

2000

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The low-lying electronic states of NbC n with five different geometries, namely, ring (R), linear (L), kite (K), Nb-terminally bound to a C n ring (T), and a structure with C−Nb−C bridge fused with a C n ring (A) (n > 3) are considered for n = 3−8. Three different levels of theoretical techniques, viz., complete active space multiconfiguration self-consistent field, multireference singles + doubles configuration interaction, and density functional theory were considered. We compute the equilibrium geometries, energy separations of the low-lying electronic states, Gibbs free energies, and heat capacity functions as a function of temperatures. For smaller clusters such as NbC3, NbC4, and NbC5, we find the ring structure to be lower with the linear structure as the first excited structure. Larger clusters exhibit odd−even alternation in that for even n the linear and ring structures are very close, whereas the clusters with odd n exhibit lower ring structures analogous to the smaller clusters. NbC6 was found to be unusual in having a linear ground state.

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Section: Introductionmentioning

confidence: 99%

Electronic Structures of Niobium Carbides: NbC_n (n = 3−8)

2000

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“…The simplest molecule formed by the interaction of Mo and C is MoC, with its ground electronic state being 3 Σ − and the electronic configuration being 1σ 2 1π 4 2σ 2 1δ 2 . 133,134 The structures of molybdenum carbide clusters of increasing sizes were investigated by Gao 135 and Cruz-Olvera. 136 138 In bulk form, molybdenum carbides are usually characterized by five different crystal phases (Figure 23): 139 α- 142 γ-MoC, 143 and η-MoC,.…”

Section: When Carbon Meets Molybdenummentioning

confidence: 99%

“…It readily forms oxides, sulfides, or carbides. The simplest molecule formed by the interaction of Mo and C is MoC, with its ground electronic state being 3 Σ – and the electronic configuration being 1σ 2 1π 4 2σ 2 1δ 2 . , The structures of molybdenum carbide clusters of increasing sizes were investigated by Gao and Cruz-Olvera . For Mo 2 C x ( x = 2–6) clusters, all of the optimized structures maintain a Mo–Mo bond, with the bond length increasing with the number of C atoms.…”

Section: When Carbon Meets Molybdenummentioning

confidence: 99%

Theoretical Perspectives on the Modulation of Carbon on Transition-Metal Catalysts for Conversion of Carbon-Containing Resources

Liu

Yang

et al. 2021

ACS Catal.

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At present, the catalytic conversion of carbon-containing resources remains a major challenge faced during the economic growth and energy mix adjustment around the world. The development of catalysts with high efficiency for the conversion of carbon-containing resources is one of the major solutions to the energy and environmental problems. During these conversion processes, carbon plays an essential role in the sense that it is not only the key element in the reactions but may also cause the modification of the chemical nature of the catalysts. Notably, comprehension of the structure−performance relationship of catalytic materials is the basis for catalyst development. In particular, the modulating role of carbon on the catalyst structures during the conversion of carbon-containing resources has attracted increasing attention. In the past five years, we have systematically studied the modulation of Fe-, Co-, Ni-, and Mo-based catalysts by carbon using theoretical approaches. In this review, with a focus on the active phases, morphologies, surface structures, electronic properties, and catalytic performances of transition-metal catalysts (Fe, Co, Ni, Mo, and other transition metals), the modulation of these catalysts by carbon will be summarized to shed light on the question of how to tune the behavior of carbon in terms of catalyst carburization and carbon-related surface reactions. This review provides systematic and fundamental information for the further design and development of catalysts for the conversion of carbon-containing resources.

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“…43 Puretzsky and coworkers 44 detected (WC 4 ) m − , m = 1−8 clusters via laser desorption Fourier transform mass spectrometry of the photolysis of W(CO) 6 . Another experimental study on anionic clusters was provided by Li and coworkers; 45 in that study, by means of photoelectron spectroscopy of WC − , the authors reported electron affinities for WC and for six low-lying electronic states within 2.4 eV above the ground state. They also reported differences in bonding and spectroscopic properties between WC and MoC.…”

Section: ■ Introductionmentioning

confidence: 99%

Potential Energy Surfaces of WC₆ Clusters in Different Spin States

et al. 2014

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Stochastic explorations of the structural possibilities of neutral WC6 clusters in several spin states lead to very rich and complex potential energy surfaces, with geometries quite different from those of pure carbon clusters at the PBE0/def2-TZVP level. The global minimum is predicted to be a triplet-state semicyclic C6 conformation having every carbon in direct coordination to the W atom. Interaction energies are comparable to those of C7 clusters, revealing very strong W-C bonding. Our results suggest that C-C interactions in the clusters should be considered as intermediate between single and double bonds.

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The electronic structure of MoC and WC by anion photoelectron spectroscopy

Cited by 41 publications

References 15 publications

Electronic Structures of Niobium Carbides: NbC_n (n = 3−8)

Electronic Structures of Niobium Carbides: NbC_n (n = 3−8)

Theoretical Perspectives on the Modulation of Carbon on Transition-Metal Catalysts for Conversion of Carbon-Containing Resources

Potential Energy Surfaces of WC₆ Clusters in Different Spin States

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The electronic structure of MoC and WC by anion photoelectron spectroscopy

Cited by 41 publications

References 15 publications

Electronic Structures of Niobium Carbides: NbCn (n = 3−8)

Electronic Structures of Niobium Carbides: NbCn (n = 3−8)

Theoretical Perspectives on the Modulation of Carbon on Transition-Metal Catalysts for Conversion of Carbon-Containing Resources

Potential Energy Surfaces of WC6 Clusters in Different Spin States

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Electronic Structures of Niobium Carbides: NbC_n (n = 3−8)

Electronic Structures of Niobium Carbides: NbC_n (n = 3−8)

Potential Energy Surfaces of WC₆ Clusters in Different Spin States