XPS observation of OH groups incorporated in an Ag(111) electrode

Zemlyanov, Dmitry; Savinova, Elena R.; Scheybal, Andreas; Doblhofer, Karl; Schlögl, Robert

doi:10.1016/s0039-6028(98)00728-6

Cited by 90 publications

(82 citation statements)

References 53 publications

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“…Nguyen van Huong et al [45] applied electroreflectance spectroscopy for in situ interphase characterization but, alike with the STM [41], were unable to identify Au-OH and, therefore, named the later as an invisible jellium state of the "incipient oxidation of gold" to infer on its unique and specific catalytic properties. Conway et al [32][33][34][35][36][37] confirmed the primary oxide monolayer coverage, asserted its sublattice intercalation, even the concerted replacementturnover and thereby arising surface reconstruction, but denied the stoichiometric phase compound state in spite of its pronounced thermal stability [43]. Weaver and Hoflund [46] along with Savinova et al [43] showed the high thermal stability of primary oxides and their incorporation into the bulk of metals.…”

Section: Specific Dipole Properties and Spillover Causes Of The Primarymentioning

confidence: 98%

“…The M-OH adsorbates are attracted towards and prefer the high coordination three-fold hollow sites on all transition elements, the adsorption energy for hollow and on-top sites being comparable for all d metals, and; consequently, they donate some electric charge to the surface to establish a dipole state (Scheme 1), in particular when a positive polarization field is imposed, as a substantially distinct example to the nonpolarizable Ertl et al issue [30] in heterogeneous catalysis. The trends in the bonding of the primary oxide (M-OH, or the "hydroxyl species" [43]) have been similar in their nature to the surface oxide (M=O), with the difference that the weaker covalent interaction with the d states is due to the lower degeneracy of the OH * -species 1π level in comparison with 2p level of M=O and, in addition, the presence of the hydrogen atom, which pools the whole OH-species away from the surface (as confirmed by dipole moment measurements) [31]. Such typical dipole repulsive features stay in the core of the spillover properties of primary oxides.…”

Section: Specific Dipole Properties and Spillover Causes Of The Primarymentioning

confidence: 99%

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Spillover Phenomena and Its Striking Impacts in Electrocatalysis for Hydrogen and Oxygen Electrode Reactions

Παπακωνσταντίνου

Jakšić

Labou

et al. 2011

Advances in Physical Chemistry

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The core subject of the present paper represents the interrelated spillover (effusion) phenomena both of the primary oxide and the H-adatoms, their theory and practice, causes, appearances and consequences, and evidences of existence, their specific properties, and their alterpolar equilibria and kinetic behavior, structural, and resulting catalytic, and double layer charging features. The aim is to introduce electron conductive and d-d interactive individual and composite (mixed valence) hypo-doxide compounds, of increased altervalent capacity, or their suboxides (Magnéli phases), as the interactive catalytic supports and therefrom provide (i) the strong metal-support interaction (SMSI) catalytic effect and (ii) dynamic spillover interactive transfer of primary oxides (M-OH) and free effusional H-adatoms for further electrode reactions and thereby advance the overall electrocatalytic activity. Since hypo-d-oxides feature the exchange membrane properties, the higher the altervalent capacity, the higher the spillover effect. In fact, altervalent hypo-d-oxides impose spontaneous dissociative adsorption of water molecules and then spontaneously pronounced membrane spillover transferring properties instantaneously resulting with corresponding bronze type (Pt/H x WO 3 ) under cathodic and/or its hydrated state (Pt/W(OH) 6 ), responsible for Pt-OH effusion, under anodic polarization, this way establishing instantaneous reversibly revertible alterpolar bronze features (Pt/H 0.35 WO 3 ⇔ Pt/W(OH) 6 ) and substantially advanced electrocatalytic properties of these composite interactive electrocatalysts. Such nanostructured-type electrocatalysts, even of mixed-valence hypo-d-oxide structures (Pt/H 0.35 WO 3 /TiO 2 /C, Pt/H x NbO 3 /TiO 2 /C), have for the first time been synthesized by the sol-gel methods and shown rather high stability, electron conductivity, and nonexchanged initial pure monobronze spillover and catalytic properties. Such a unique electrocatalytic system, as the striking target issue of the present paper, has been shown to be the superior for substantiation of the revertible cell assembly for spontaneous reversible alterpolar interchanges between PEMFC and WE. The main target of the present thorough review study has been to throw some specific insight light on the overall spillover phenomena and their effects in electrocatalysis of oxygen and hydrogen electrode reactions from diverse angles of view and broad contemporary experimental methods and approaches (XPS, FTIR, DRIFT, XRD, potentiodynamic spectra, UHRTEM).

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Section: Specific Dipole Properties and Spillover Causes Of The Primarymentioning

confidence: 98%

Section: Specific Dipole Properties and Spillover Causes Of The Primarymentioning

confidence: 99%

Spillover Phenomena and Its Striking Impacts in Electrocatalysis for Hydrogen and Oxygen Electrode Reactions

Παπακωνσταντίνου

Jakšić

Labou

et al. 2011

Advances in Physical Chemistry

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“…43 However, a high binding energy feature between 531.5 and 532.5 eV was occasionally observed for silver foils exposed to O 2 at high temperatures, which is not a new atomic oxygen species on silver, but a silicon oxide related feature. Fig.…”

Section: Surface Impuritiesmentioning

confidence: 99%

The silver–oxygen system in catalysis: new insights by near ambient pressure X-ray photoelectron spectroscopy

Rocha

Oestereich

Demidov

et al. 2012

Phys. Chem. Chem. Phys.

138

171

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We addressed the interaction of oxygen with silver by synchrotron based near ambient pressure X-ray photoelectron spectroscopy at temperatures relevant for industrial oxidation reactions performed with silver catalysts. For silver single crystals, polycrystalline foils and powders in equilibrium with gas phase O 2 , we observed the dynamics of the formation of five different atomic oxygen species with relative abundances depending on the temperature and time. Correlation of their formation kinetics with spectroscopic features and thermal stability indicates that these are distinct species with different electronic structures, which might relate to the different roles of silver in oxidation reactions.

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“…OH (a) /Ag (1 1 0) is characterised by an O 1s binding energy of 531.7 eV [58] and is stable to temperatures ∼280 K, above which disproportionation to O (a) + H 2 O (g) occurs [58][59][60]. By comparison, hydroxy species dissolved in the bulk layers of silver have high thermal stability and exist to temperatures in excess of 773 K [61]. The FWHM of the 532.0 eV peak was identical to that observed for O ␤ (3.4 eV).…”

Section: Xps Characterisation Of the Silver Catalyst Before And Aftermentioning

confidence: 99%

Mechanism and active sites for the partial oxidation of methanol to formaldehyde over an electrolytic silver catalyst

Waterhouse

Bowmaker

Metson

2004

Applied Catalysis A: General

117

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XPS observation of OH groups incorporated in an Ag(111) electrode

Cited by 90 publications

References 53 publications

Spillover Phenomena and Its Striking Impacts in Electrocatalysis for Hydrogen and Oxygen Electrode Reactions

Spillover Phenomena and Its Striking Impacts in Electrocatalysis for Hydrogen and Oxygen Electrode Reactions

The silver–oxygen system in catalysis: new insights by near ambient pressure X-ray photoelectron spectroscopy

Mechanism and active sites for the partial oxidation of methanol to formaldehyde over an electrolytic silver catalyst

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