Interaction of NO and O2 with Pd(111) surfaces. I.

Conrad, H.; Ertl, G.; Küppers, J.; Latta, E.E.

doi:10.1016/0039-6028(77)90304-1

Cited by 240 publications

(75 citation statements)

References 12 publications

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“…In order to rule out desorption from the sample holder, the Pd(111) single crystal was replaced for a stainless steel disk and no oxygen desorption was observed after identical treatments. The high-temperature TPD feature was reported in the literature [18,22,23] and was assigned to dissolved oxygen. The amount of highly stable oxygen increased with the treatment temperature.…”

Section: 3temperature Programmed Desorptionmentioning

confidence: 99%

In situ XPS study of Pd(111) oxidation at elevated pressure, Part 2: Palladium oxidation in the 10−1mbar range

et al. 2006

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The oxidation of the Pd(111) surface was studied by in situ XPS during heating and cooling in 0.4 mbar O 2 . The in situ XPS data were complemented by ex situ TPD results. A number of oxygen species and oxidation states of palladium were observed in situ and ex situ. At 430 K, the Pd(111) surface was covered by a 2D oxide and by a supersaturated O ads layer. The supersaturated O ads layer transforms into the Pd 5 O 4 phase upon heating and disappears completely at approximately 470 K. Simultaneously, small clusters of PdO, PdO seeds, are formed. Above 655 K, the bulk PdO phase appears and this phase decomposes completely at 815 K. Decomposition of the bulk oxide is followed by oxygen dissolution in the near-surface region and in the bulk. The oxygen species dissolved in the bulk is more favoured at high temperatures because oxygen cannot accumulate in the near-surface region and diffusion shifts the equilibrium towards the bulk species. The saturation of the bulk "reservoir" with oxygen leads to increasing the uptake of the near-surface region species. Surprisingly, the bulk PdO phase does not form during cooling in 0.4 mbar O 2 , but the Pd 5 O 4 phase appears below 745 K. This is proposed to be due to a kinetic limitation of PdO formation because at high temperature the rate of PdO seed formation is compatible with the rate of decomposition.

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Section: 3temperature Programmed Desorptionmentioning

confidence: 99%

In situ XPS study of Pd(111) oxidation at elevated pressure, Part 2: Palladium oxidation in the 10−1mbar range

et al. 2006

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“…The interaction of palladium with oxygen has been studied extensively under low pressure conditions (< 10 -6 mbar), (see e.g. [11][12][13][14][15][16][17][18] and refs.…”

Section: Introductionmentioning

confidence: 99%

In situ XPS study of Pd(111) oxidation. Part 1: 2D oxide formation in 10−3mbar O2

et al. 2006

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The oxidation of the Pd(111) surface was studied by in situ XPS during heating and cooling in 3×10 The surface was completely covered with the 2D oxide between 600 K and 655 K. Depth profiling by photon energy variation confirmed the surface nature of the 2D oxide. The 2D oxide decomposed completely above 717 K. Diffusion of oxygen in the palladium bulk occurred at these temperatures. A substantial oxygen signal assigned to the dissolved species was detected even at 923 K. The dissolved oxygen was characterised by the O 1s core level peak at 528.98 eV. The "bulk" nature of the dissolved oxygen species was verified by depth profiling. During cooling in 3×10 -3 mbar O 2 , the oxidised Pd 2+ species appeared at 788 K whereas the 2D oxide decomposed at 717 K during heating. The surface oxidised states exhibited an inverse hysteresis. The oxidised palladium state observed during cooling was assigned to a new oxide phase, probably the ( 67 67 × )R12.2° structure.

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“…These peaks at 2.7 and 14.8 eV originate from 2π and 4σ orbitals of NO molecules, respectively, as determined by several authors [13][14][15][16]. With increasing annealing temperature, the two peaks of 1π+5σ orbitals gradually decrease and the peaks at 9.4 and 11.2 eV disappear at 423 K and 393 K, respectively.…”

Section: Almentioning

confidence: 60%

Influence of Step Sites on Thermal Behavior of NO on Stepped Pd(112) Studied by AES, XPS and UPS

Irokawa

Ito

Okada

et al. 2009

e-J. Surf. Sci. Nanotechnol.

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The adsorption and thermal dissociation of nitric oxide on a stepped Pd(112) surface has been investigated by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS). NO undergoes molecular adsorption on a stepped Pd(112) surface at 300 K. With increasing temperature, some NO adsorbed on the surface desorbs molecularly and the remaining NO starts to dissociate into nitrogen and oxygen. The NO dissociation takes place preferentially at the step sites. All NO molecules adsorbed on the surface dissociate above 423 K. Nitrogen desorbs from the surface above 700 K but oxygen exists on the surface or subsurface. UPS results show that the peak at 11.2 eV below Fermi level (EF), originating from the 1π+5σ orbital of NO adsorbed on step sites of Pd (112), disappear at a lower temperature than does the peak of NO adsorbed on terrace sites. This indicates that NO molecules adsorbed on step sites are dissociated at a temperature lower than those at terrace sites. The dissociation activity of NO on Pd(112) is stronger than on the (111) and (110) surfaces, but weaker than on the (100) surface. The order of the dissociation activity is Pd(100) > Pd(112) > Pd(111) > Pd(110).

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Interaction of NO and O2 with Pd(111) surfaces. I.

Cited by 240 publications

References 12 publications

In situ XPS study of Pd(111) oxidation at elevated pressure, Part 2: Palladium oxidation in the 10−1mbar range

In situ XPS study of Pd(111) oxidation at elevated pressure, Part 2: Palladium oxidation in the 10−1mbar range

In situ XPS study of Pd(111) oxidation. Part 1: 2D oxide formation in 10−3mbar O2

Influence of Step Sites on Thermal Behavior of NO on Stepped Pd(112) Studied by AES, XPS and UPS

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