Modification of the surface reactivity of Mo(110) upon carbide formation

Frühberger, Bernd; Chen, J.G.

doi:10.1016/0039-6028(95)00837-3

Cited by 56 publications

(55 citation statements)

References 28 publications

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“…55 The chambers are equipped with low-energy electron diffraction (LEED), an Auger electron spectrometer (AES), and a quadrupole mass spectrometer (QMS) used for monitoring background residual gas and detecting desorbed species during TPD. The details of the HREEL spectrometer are discussed in the companion paper.…”

Section: Methodsmentioning

confidence: 99%

Reaction Pathways of Acetylene on Pd/W(211): A TPD and HREELS Investigation

Abdelrehim¹,

Pelhos²,

Madey³

et al. 1998

J. Phys. Chem. B

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In an ongoing investigation to study structure-reactivity relationships on bimetallic surfaces, acetylene cyclotrimerization to form benzene is of particular interest: in this structure-sensitive catalytic reaction, C-C and C-H bonds can be formed readily under ultrahigh vacuum (UHV) conditions without C-C bond breaking. In this paper, we present results for acetylene cyclization and hydrogenation on Pd/W(211). Pd on W is chosen because it is a morphologically unstable system, and W(211) facets develop after annealing Pd/W(111) to g700 K. Temperature-programmed desorption (TPD) results exhibit negligible amounts of benzene detected from acetylene adsorption on clean W(211). A single monolayer (ML) of Pd on W(211) decreases the high reactivity toward acetylene decomposition and several different reaction pathways are accessed, including hydrogenation of C 2 H 2 to C 2 H 4 and cyclotrimerization of C 2 H 2 to form C 6 H 6 . The cyclotrimerization reaction produces three benzene desorption states at ∼340, ∼390, and ∼430 K. In addition, the detection of C 4 H 6 during TPD provides evidence that an elusive C 4 H 4 intermediate is present on the surface. Furthermore, ethylene is observed in substantial yields, lending insight into the activity of the bimetallic system. The use of high-resolution electron energy-loss spectroscopy (HREELS) provides complementary information regarding the reaction mechanisms of acetylene on the Pd/W(211) surfaces.

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Section: Methodsmentioning

confidence: 99%

Reaction Pathways of Acetylene on Pd/W(211): A TPD and HREELS Investigation

Abdelrehim¹,

Pelhos²,

Madey³

et al. 1998

J. Phys. Chem. B

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“…A large body of literature exists on the possibility of using transition metal carbides to mimic the catalytic properties of Pt-group metals [12][13][14][15][16][17][18]. In particular, there have been many studies on tungsten and molybdenum carbides since Levy and Boudart suggested that WC displayed Pt-like behavior in several catalytic reactions [18].…”

Section: Introductionmentioning

confidence: 99%

Cyclic voltammetry and X-ray photoelectron spectroscopy studies of electrochemical stability of clean and Pt-modified tungsten and molybdenum carbide (WC and Mo2C) electrocatalysts

Weigert

Esposito

Chen

2009

Journal of Power Sources

103

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“…19,21,23 This procedure was repeated until a sharp p(4ϫ4) LEED pattern and an AES C/Mo atomic ratio of approximately 0.25-0.30 was obtained. The carbon-modified surface was prepared by dosing 300 L of ethylene onto a clean Mo ͑110͒ surface held at 100 K, followed by annealing at 1100 K for 5-10 min.…”

Section: B Carbon-modified P"4؋4…-c/mo "110… Surfacementioning

confidence: 99%

“…4,[19][20][21][22] They observed significant differences between the adsorption of CO and ethylene on the clean Mo ͑110͒ and p(4ϫ4)-C/Mo ͑110͒ surfaces, which include different surface intermediates, decomposition pathways, and adsorption sites. Frühberger and Chen have done a comprehensive study of hydrocarbon reactivity on clean, carbon-modified, nitrogen-modified, and oxygenmodified Mo ͑110͒ surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…4,[19][20][21][22] They observed significant differences between the adsorption of CO and ethylene on the clean Mo ͑110͒ and p(4ϫ4)-C/Mo ͑110͒ surfaces, which include different surface intermediates, decomposition pathways, and adsorption sites. 19 Young and Slavin have already studied the structure of the p(4ϫ4)-C/Mo ͑110͒ surface, proposing that the adsorbed carbon atoms sit in the hollows at the centers of each unit cell of the Mo ͑110͒ substrate. Similar results were also reported for cyclohexene decomposition.…”

Section: Introductionmentioning

confidence: 99%

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Reaction of 1,2-ethanedithiol on clean, sulfur-modified, and carbon-modified Mo (110) surfaces

Roe

Schulz

1998

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Articles you may be interested inAngular and energy distributions of D 2 molecules desorbing from sulfur and oxygen modified V(111) surfaces Chemical and spectroscopic surface science investigation of MoO 3 and MoO 3 /Al 2 O 3 ultrathin films J. Vac. Sci. Technol. A 15, 1717 (1997); 10.1116/1.580926 Adsorption state of hydrogen sulfide on the GaAs (001)-(4×2) surface J.The reactivity of 1,2-ethanedithiol on the clean Mo ͑110͒ and p(4ϫ4)-C/Mo ͑110͒ surfaces has been investigated as a function of sulfur coverage using temperature programmed desorption ͑TPD͒, Auger electron spectroscopy, and low energy electron diffraction. TPD experiments performed on both surfaces produced similar reaction products, although changes were observed in selectivity. On the clean Mo ͑110͒ surface, the major products observed during TPD experiments were acetylene, ethylene, vinyl thiol, and ethanethiol. However, the reaction of ethanedithiol on the p(4 ϫ4)-C/Mo ͑110͒ surface produced acetylene, ethylene, and ethanedithiol. Product molecules are thought to arise from two distinct types of surface intermediates: ͑1͒ a monodentate thiolate species bound to the surface through only one of the ethanedithiol sulfur atoms, and ͑2͒ a bidentate organosulfur metallocycle bound to the surface through both of the ethanedithiol sulfur atoms. We propose that vinyl thiol and ethanethiol are produced via C-S bond scission and subsequent hydride elimination of the monodentate thiolate intermediate, and that the bidentate surface metallocycles undergo C-S bond scission to yield acetylene and ethylene. On the carbon-modified surface, complete desulfurization of ethanedithiol occurs upon decomposition, yielding only hydrocarbon products. With increasing sulfur coverage, a decrease in reactivity and a shift in desorption features to lower temperatures is observed for ethanedithiol on the clean and carbon-modified surfaces.

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Modification of the surface reactivity of Mo(110) upon carbide formation

Cited by 56 publications

References 28 publications

Reaction Pathways of Acetylene on Pd/W(211): A TPD and HREELS Investigation

Reaction Pathways of Acetylene on Pd/W(211): A TPD and HREELS Investigation

Cyclic voltammetry and X-ray photoelectron spectroscopy studies of electrochemical stability of clean and Pt-modified tungsten and molybdenum carbide (WC and Mo2C) electrocatalysts

Reaction of 1,2-ethanedithiol on clean, sulfur-modified, and carbon-modified Mo (110) surfaces

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