Surface chemistry of the non-basal planes of cobalt: The structure, stability, and reactivity of Co(101̄2)-CO

Prior, K. A.; Schwaha, K.; Lambert, Richard M.

doi:10.1016/0039-6028(78)90001-8

Cited by 106 publications

(39 citation statements)

References 18 publications

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“…This has also been reported recently in a study on a non-basal plane, on Co( 1012) [7], where the structural changes during the phase transition are directly visible in the diffraction picture since the diffraction spots from both phases do not 0039-6028/83/0000-0000/$03.00 0 1983 North-Holland coincide. Similar observations have been made here.…”

Section: Introductionsupporting

confidence: 72%

Structure determination of the clean Co(112̄0) surface by LEED

1983

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The atomic structure of the (1120) surface of cobalt has been determined by LEED using six intensity spectra at normal incidence. The surface exhibits the truncated bulk structure with a contraction of the first interlayer spacing by about 8.5% with respect to the bulk value. Quantitative evaluation of the LEED spectra was done using Zanazzi and Jona's and Pendry's r-factors. The minimum averaged r-factors are ?, = 0.09 and F, = 0.22. No change of the interatomic distances within the plane could be detected and no rearrangement of the surface structure takes place up to temperatures shortly below the transition temperature.

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Section: Introductionsupporting

confidence: 72%

Structure determination of the clean Co(112̄0) surface by LEED

1983

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“…For single-crystalline surfaces, different results concerning carbon monoxide dissociation can be found in the literature: on CoA C H T U N G T R E N N U N G (0001) [28] and CoA C H T U N G T R E N N U N G (101 0) [29] only molecular adsorption was observed, whereas evidence for dissociative adsorption was reported for the higher-index surfaces CoA C H T U N G T R E N N U N G (112 0) [28] and CoA C H T U N G T R E N N U N G (101 2). [30,31] Activation of the (0001) surface for carbon monoxide dissociation was achieved by deposition of magnesia as a promoter [32] or by sputtering with argon ions. [33] For nanoparticles grown under UHV conditions, carbon monoxide dissociation has not been reported so far to the best of our knowledge.…”

Section: Introductionmentioning

confidence: 99%

UHV Studies of Methanol Decomposition on Mono‐ and Bimetallic CoPd Nanoparticles Supported on Thin Alumina Films

et al. 2008

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Bimetallic nanoparticles often turn out to be superior to the corresponding monometallic systems with respect to their catalytic properties. To study such effects for the methanol decomposition reaction, model catalysts were prepared by physical vapor deposition of Pd and Co under ultrahigh-vacuum (UHV) conditions. Monometallic Pd and Co particles as well as CoPd core-shell particles were generated on an epitaxial alumina film grown on NiAl(110). The interaction with methanol is examined by temperature-programmed desorption of methanol and carbon monoxide and by X-ray photoelectron spectroscopy. The decomposition of methanol proceeds in two reaction pathways independent of the particle composition: complete dehydrogenation towards carbon monoxide and hydrogen, and C--O bond scission yielding carbon deposits. Pd is the most active material studied here. The relative importance of the two channels varies for the different particle systems: on Pd dehydrogenation is preferred, whereas the C--O bond cleavage is more pronounced on Co. The bimetallic clusters show a moderate performance for both pathways. Carbon deposition poisons the model catalysts by blocking the adsorption sites for methoxide, which is the first intermediate product during methanol decomposition. In particular on Co, large amounts of carbon deposits can also be caused by dissociation of the final product of the dehydrogenation pathway, carbon monoxide. A comparison with the results of methanol decomposition on Co, Pd, and CoPd catalysts in continuous-flow reactors demonstrates that the findings of the present UHV study are relevant for catalytic performance under high-pressure conditions.

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“…Another "borderline" metal, cobalt, needs an even more pronounced crystallographic corrugation for becoming dissociation-active: While the Co(0001) and the Co-(10-10) surfaces do not spontaneously dissociate CO, 35,36 the still rougher Co (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) face is active in cleaving the C-O bond. 37 The same thing holds, by the way, for ruthenium, where the "lower"-index planes (0001) and (10-10) do not dissociate CO but the "higher-index" plane (11-21) readily does. 60 Figure 11.…”

Section: Co Dissociation and Atomic C + O Adsorptionmentioning

confidence: 57%

Dissociation of Carbon Monoxide on the Rhenium(10-10) Surface

2004

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We have studied the interaction of carbon monoxide with a Re(10-10) surface between 150 and 800 K by means of low-energy electron diffraction (LEED), temperature-programmed thermal desorption, and work function change (∆ ) measurements. We find two (temperature-dependent) interaction/reaction channels: At 200 K, CO forms molecular (R) states with binding energies between 95 and 118 kJ/mol. At a coverage of Θ CO ) 0.5, a c(2 × 2) LEED phase forms; for Θ CO > 0.5, a dim (2 × 3) structure is observed. The work function change of ∆ max ) +780 meV indicates negatively polarized adsorbed CO molecules. Exposure at 500 K exclusively yields dissociated CO as deduced from high-temperature desorption states (185 kJ/mol < E des < 210 kJ/mol), second-order reaction kinetics, and the formation of a sharp (1 × 2) LEED pattern at Θ CO ) 0.25 (Θ C + Θ O ) 0.50) associated with the least strongly bound 1 CO state. ∆ max amounts to merely +400 meV. Smaller CO coverages (0.125 < Θ < 0.16) give rise to a c(2 × 4) LEED structure. Upon heating, but prior to desorption, both superstructures undergo an order-disorder phase transition. Our results are discussed in terms of face specifities of CO dissociation, CO binding states, and structures and are compared with previous work on CO interaction/dissociation on related transition-metal surfaces.

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Surface chemistry of the non-basal planes of cobalt: The structure, stability, and reactivity of Co(101̄2)-CO

Cited by 106 publications

References 18 publications

Structure determination of the clean Co(112̄0) surface by LEED

Structure determination of the clean Co(112̄0) surface by LEED

UHV Studies of Methanol Decomposition on Mono‐ and Bimetallic CoPd Nanoparticles Supported on Thin Alumina Films

Dissociation of Carbon Monoxide on the Rhenium(10-10) Surface

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