Determination of O[H] and CO Coverage and Adsorption Sites on PtRu Electrodes in an Operating PEM Fuel Cell

Roth, Christina; Benker, Nathalie; Buhrmester, Thorsten; Mazurek, Marian; Loster, Matthias; Fueß, H.; Koningsberger, D.C.; Ramaker, David E.

doi:10.1021/ja050139f

Cited by 188 publications

(205 citation statements)

References 56 publications

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“…For supported metal particles, the effect of the support on the catalytic properties has been determined by several techniques, for example, XPS, FT-IR analysis of adsorbed CO, and newly developed delta XANES and atomic XAFS (AXAFS) techniques. [8][9][10][11][12][13][14][15] In particular, the application of AXAFS has, in our opinion, led to a better understanding of metal-support interaction effects. [8,[15][16][17] AXAFS is sensitive to changes in the potential around the X-ray absorbing atom.…”

mentioning

confidence: 98%

Application of AXAFS Spectroscopy to Transition‐Metal Oxides: Influence of the Nearest and Next Nearest Neighbour Shells in Vanadium Oxides

Keller

Weckhuysen

Koningsberger

2007

Chemistry A European J

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IntroductionMany parameters affect the catalytic properties of transition-metal oxide catalysts, for example, metal oxide loading, pre-treatment conditions, molecular structure, electronic structure, and the nature of the supporting oxide. [1][2][3][4][5][6][7] Various researchers have investigated the activities and selectivities of metal oxide catalysts. However, little is known about the parameters that are truly responsible for the catalytic action of transition-metal oxides.To study the effect of the support on the catalytic performance, one has to find a tool that is capable of probing the influence of the local environment (e.g., the support or promoters) on the properties of the catalytically active species, that is, a metal particle or metal oxide cluster. Metal-A C H T U N G T R E N N U N G (oxide)-support interactions can be ascribed to a structural (particle/cluster size and shape) effect, but can also have an electronic origin. For supported metal particles, the effect of the support on the catalytic properties has been determined by several techniques, for example, XPS, FT-IR analysis of adsorbed CO, and newly developed delta XANES and atomic XAFS (AXAFS) techniques. [8][9][10][11][12][13][14][15] In particular, the application of AXAFS has, in our opinion, led to a better understanding of metal-support interaction effects. [8,[15][16][17] AXAFS is sensitive to changes in the potential around the X-ray absorbing atom. The potential field around an atom is mainly determined by the first and second coordination spheres. O Grady et al. have shown for Pt/Ru alloys that the AXAFS intensity changes systematically with the composition of the alloy. [18] Thus, when the number of Ru atoms around a Pt atom increases, the intensity of the FT AXAFS peak increases and the peak centroid shifts to lower values of R. Comparison of these effects with the effects observed for a Pt electrode as a function of the applied voltage suggests that the first coordination shell of the Pt in the Pt/Ru alloy influences the electronic properties (inter-A C H T U N G T R E N N U N G atomic potential) of the Pt atom. [18,19] The effect of changes in the coordination around the absorber atom has been further illustrated for Pt by van Dorssen et al., who compared the AXAFS of a Pt foil with that of bulk Na 2 Pt(OH) 6 . The AXAFS intensity was found to be significantly higher in the Abstract: The influence of changes in coordination number, interatomic distances, and oxidation state on the intensity and centroid position of the Fourier transform (FT) of the atomic X-ray absorption fine structure (AXAFS) peak of vanadium oxide bulk model compounds and aluminasupported vanadium oxide clusters has been investigated. Using Na 3 VO 4 and V 2 O 5 as model compounds, it has been shown that the nearest neighbour shells have a pronounced influence on the AXAFS intensity; specifically, a 40 % decrease in intensity was observed between these two compounds. Secondly, the influence of partial reduction of the vanadium oxide species has been dete...

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mentioning

confidence: 98%

Application of AXAFS Spectroscopy to Transition‐Metal Oxides: Influence of the Nearest and Next Nearest Neighbour Shells in Vanadium Oxides

Keller

Weckhuysen

Koningsberger

2007

Chemistry A European J

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“…For example, adsorption is involved in the mechanism of charge transfer reactions at electrode surfaces [1][2][3], capacitance dispersion in the electrode/solution interface [4][5][6][7][8][9][10] and self-assembly processes [11][12][13][14][15][16]. As such, adsorption is a crucial subject for various technologic research fields, ranging from surface modification [17][18][19] to heterogeneous catalysis applied to fuel cells [20][21][22]. In the last decades, ab initio quantum calculations, especially those using density functional theory (DFT) [23][24][25][26][27][28][29][30][31][32][33][34][35][36], and molecular simulation techniques, namely Monte Carlo (MC) [37][38][39][40][41][42][43][44][45] and molecular dynamics (MD) [46]…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo Simulation of the Solvent Contribution to the Potential of Mean Force for the Phenol Adsorption on Au(210) Electrodes

Neves

Motheo

Fartaria

et al. 2009

Port. Electrochim. Acta

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This paper reviews some recent canonical Monte Carlo simulations of the Au(210)/H 2 O interface using a DFT force field developed by us. New results are reported on the solvent contribution to the potential of mean force (PMF) for the phenol adsorption, from a dilute aqueous solution, onto the Au(210) surface. The Monte Carlo simulations show the common features normally observed in the simulation of water in contact with metallic surfaces, where the water molecules adsorb forming bilayers. The molecules adsorbed over the Top gold sites form hydrogen bonds between the first and second solvent layers. The PMF calculations indicate that the phenol molecule penetrates the solvent layers with the aromatic ring in a perpendicular configuration and the oxygen atom pointing to the surface. The PMF results also suggest the existence of hydrogen bonds between the phenol molecule and the first solvent layer of the water molecules adsorbed onto the Top sites.

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“…To this aim, techniques which provide high time resolution, but do not require long range order and can be applied in situ, are crucial for interrogating the kinetic behavior of (often disordered) bimetallic nanocatalysts under operating conditions. For example, in situ, dispersive and quick X‐ray absorption spectroscopy (XAS) have established a role of utmost importance in uncovering the motifs of (bi)metallic nanoparticle restructuring 13, 14, 15, 16, 17, 18…”

mentioning

confidence: 99%

Kinetics of Lifetime Changes in Bimetallic Nanocatalysts Revealed by Quick X‐ray Absorption Spectroscopy

et al. 2018

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Alloyed metal nanocatalysts are of environmental and economic importance in a plethora of chemical technologies. During the catalyst lifetime, supported alloy nanoparticles undergo dynamic changes which are well‐recognized but still poorly understood. High‐temperature O2–H2 redox cycling was applied to mimic the lifetime changes in model Pt13In9 nanocatalysts, while monitoring the induced changes by in situ quick X‐ray absorption spectroscopy with one‐second resolution. The different reaction steps involved in repeated Pt13In9 segregation‐alloying are identified and kinetically characterized at the single‐cycle level. Over longer time scales, sintering phenomena are substantiated and the intraparticle structure is revealed throughout the catalyst lifetime. The in situ time‐resolved observation of the dynamic habits of alloyed nanoparticles and their kinetic description can impact catalysis and other fields involving (bi)metallic nanoalloys.

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Determination of O[H] and CO Coverage and Adsorption Sites on PtRu Electrodes in an Operating PEM Fuel Cell

Cited by 188 publications

References 56 publications

Application of AXAFS Spectroscopy to Transition‐Metal Oxides: Influence of the Nearest and Next Nearest Neighbour Shells in Vanadium Oxides

Application of AXAFS Spectroscopy to Transition‐Metal Oxides: Influence of the Nearest and Next Nearest Neighbour Shells in Vanadium Oxides

Monte Carlo Simulation of the Solvent Contribution to the Potential of Mean Force for the Phenol Adsorption on Au(210) Electrodes

Kinetics of Lifetime Changes in Bimetallic Nanocatalysts Revealed by Quick X‐ray Absorption Spectroscopy

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