Pd(111) versus Pd–Au(111) in carbon monoxide oxidation under elevated pressures

Piednoir, Agnès; Languille, Marie-Angélique; Piccolo, L.; Valcárcel, Ana; Aires, F.J. Cadete Santos; Bertolini, J.C.

doi:10.1007/s10562-007-9047-3

Cited by 28 publications

(35 citation statements)

References 33 publications

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“…[30][31][32][33][34][35][36][37][38][39][40] In the case of Pd(100), it has been shown experimentally that the higher activity of this surface towards CO oxidation at these conditions coincides with the presence of the √ 5 surface oxide. 30,32,35,38,39,41 Kinetic Monte-Carlo simulations support the view that a surface oxide on Pd(100) could be responsible for increased reactivity.…”

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confidence: 96%

Reversed Hysteresis during CO Oxidation over Pd₇₅Ag₂₅(100)

et al. 2016

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CO oxidation over Pd(100) and Pd 75 Ag 25 (100) has been investigated by a combination of near-ambient pressure X-ray photoelectron spectroscopy, quadrupole mass spectrometry, density functional theory calculations and micro-kinetic modeling. For both surfaces, hysteresis is observed in the CO 2 formation during heating and cooling cycles. Whereas normal hysteresis with higher light-off temperature than extinction temperature is present for Pd(100), reversed hysteresis is observed for Pd 75 Ag 25 (100).The reversed hysteresis can be explained from dynamic changes in the surface composition. At the beginning of the heating ramp, the surface is rich in palladium which gives a CO coverage that poisons the surface until the desorption rate becomes sufficiently high. The thermodynamic preference for an Ag rich surface in the absence of adsorbates promotes diffusion of Ag from the bulk to the surface as CO desorbs.During the cooling ramp, an appreciable surface coverage is reached at temperatures too low for efficient diffusion of Ag back into the bulk. The high concentration of Ag in the surface leads to a high extinction temperature and, consequently, the reversed hysteresis.

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confidence: 96%

Reversed Hysteresis during CO Oxidation over Pd₇₅Ag₂₅(100)

et al. 2016

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“…However, some studies also indicate Pd surfaces covered 37 by atomic oxygen as highly active [8,17], and generally both will exhibit activity. For Pd(100), the 38 presence of a (√5x√5)R27° surface oxide (henceforth denoted √5) is found to exist when the surface 39 is highly active towards CO oxidation [5,6,8,10,14,17,18], and this is consistent with the reaction 40 following a Mars-van Krevelen mechanism with gas-phase CO reacting with the surface oxide to 41 form CO2 [5][6][7]9,11,[13][14][15]19]. The presence of the surface oxide during high CO2 production is also 42 supported by kinetic Monte-Carlo simulations [20,21].…”

Section: Introductionmentioning

confidence: 66%

“…Surface oxides rather than surfaces covered by chemisorbed oxygen have been 35 observed as the most active towards CO oxidation under near ambient as well as more realistic 36 conditions (above ambient pressure) [5][6][7][8][9][10][11][12][13][14][15][16]. However, some studies also indicate Pd surfaces covered 37 by atomic oxygen as highly active [8,17], and generally both will exhibit activity.…”

Section: Introductionmentioning

confidence: 99%

Near Ambient Pressure XPS Investigation of CO Oxidation Over Pd3Au(100)

et al. 2017

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19The CO oxidation behavior under excess oxygen and near stoichiometric conditions over the surface 20 of Pd3Au(100) has been studied by combining near-ambient pressure X-ray photoelectron 21 spectroscopy and quadrupole mass spectrometry and compared to Pd(100). During heating and 22 cooling cycles, normal hysteresis in the CO2 production, i.e. with the light-off temperature being 23 higher than the extinction temperature, is observed for both surfaces. On both Pd3Au(100) and 24Pd(100) the (√5x√5)R27° surface oxide structure is present during CO2 production under excess 25 oxygen conditions (O2:CO = 10:1), while at near stoichiometric conditions (O2:CO = 1:1) the surfaces 26 are covered with atomic oxygen. Au as alloying element hence induces only minor differences in the 27 observed hysteresis and the active phase compared to pure Pd. Alloying with Au thus yields a 28 different behavior compared to Ag, where reversed hysteresis is observed for CO2 production over 29 Pd75Ag25(100) at similar conditions [Fernandes et al., ACS Catal. (2016)

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“…Metal/metal interfaces show novel physical and chemical properties [4,9,[14][15][16]. In particular, bimetallic surfaces involving gold [7,[17][18][19] are extensively investigated due to the high catalytic activity of nanostructured gold systems [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

O2 dissociation in Na-modified gold ultrathin layer on Cu(111)

Politanoa

Chiarello

2010

Gold Bull

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High-resolution electron energy loss spectroscopy has been used to investigate the catalytic properties of Na-doped Au monolayer grown on Cu(111). The presence of Na atoms allows the dissociation of oxygen molecules and the stabilization of atomic oxygen. The strong reduction of the dissociation barrier for O 2 promoted by Na could readily favor many surface chemical reactions, due to the key role of atomic oxygen in many oxidation processes catalyzed by gold.

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Pd(111) versus Pd–Au(111) in carbon monoxide oxidation under elevated pressures

Cited by 28 publications

References 33 publications

Reversed Hysteresis during CO Oxidation over Pd₇₅Ag₂₅(100)

Reversed Hysteresis during CO Oxidation over Pd₇₅Ag₂₅(100)

Near Ambient Pressure XPS Investigation of CO Oxidation Over Pd3Au(100)

O2 dissociation in Na-modified gold ultrathin layer on Cu(111)

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Pd(111) versus Pd–Au(111) in carbon monoxide oxidation under elevated pressures

Cited by 28 publications

References 33 publications

Reversed Hysteresis during CO Oxidation over Pd75Ag25(100)

Reversed Hysteresis during CO Oxidation over Pd75Ag25(100)

Near Ambient Pressure XPS Investigation of CO Oxidation Over Pd3Au(100)

O2 dissociation in Na-modified gold ultrathin layer on Cu(111)

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Reversed Hysteresis during CO Oxidation over Pd₇₅Ag₂₅(100)

Reversed Hysteresis during CO Oxidation over Pd₇₅Ag₂₅(100)