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Markusse, AP Abraham; Kuster, Bfm Ben; Koningsberger, DC Diek; Marin, Gbmm Guy

doi:10.1023/a:1019007601442

Cited by 62 publications

(59 citation statements)

References 16 publications

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“…The larger size is attributed to the presence of a significant oxygen content in the Pt particles in accordance with the literature 50 and observed here by GIXANES.…”

Section: In Situ Characterization Under Reduction Conditions and Elevsupporting

confidence: 91%

Combined TPRx, in situ GISAXS and GIXAS studies of model semiconductor-supported platinum catalysts in the hydrogenation of ethene

Wyrzgol

Schäfer

Lee

et al. 2010

Phys. Chem. Chem. Phys.

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The preparation, characterization and catalytic reactivity of a GaN supported Pt catalyst in the hydrogenation of ethene are presented in this feature article, highlighting the use of in situ characterization of the material properties during sample handling and catalysis by combining temperature programmed reaction with in situ grazing incidence small-angle X-ray scattering and X-ray absorption spectroscopy. The catalysts are found to be sintering resistant at elevated temperatures as well as during reduction and hydrogenation reactions. In contrast to Pt particles of approximately 7 nm diameter, smaller particles of 1.8 nm in size are found to dynamically adapt their shape and oxidation state to the changes in the reaction environment. These smaller Pt particles also showed an initial deactivation in ethene hydrogenation, which is paralleled by the change in the particle shape. The subtle temperature-dependent X-ray absorbance of the 1.8 nm sized Pt particles indicates that subtle variations in the electronic structure induced by the state of reduction by electron tunnelling over the Schottky barrier between the Pt particles and the GaN support can be monitored.

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“…The larger size is attributed to the presence of a significant oxygen content in the Pt particles in accordance with the literature 50 and observed here by GIXANES.…”

Section: In Situ Characterization Under Reduction Conditions and Elevsupporting

confidence: 91%

Combined TPRx, in situ GISAXS and GIXAS studies of model semiconductor-supported platinum catalysts in the hydrogenation of ethene

Wyrzgol

Schäfer

Lee

et al. 2010

Phys. Chem. Chem. Phys.

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“…2), also the increase in the area of the third voltammetric peak (N 3 ) follows a t h 1/2 kinetics, suggesting again a diffusion mechanism. Considering that N 1 corresponds to the formation of an oxide monolayer at the Pt/YSZ interface and N 3 to the formation of multilayer, one can estimate the diffusion length L t at a given time from L t =d N 3 (t h )/N 1 , where N 3 (t h ) is the amount of oxygen atoms in the multilayer at time t h , N 1 is the amount of oxygen atoms in the monolayer at the Pt/YSZ interface (6.6·10 14 atom) and d is the average thickness of an oxide layer (2.7×10 −10 m, estimated with the Pt-Pt atomic distance [11]), a diffusion coefficient of D=3·10 -22 m 2 /s is calculated. This value is typical for a diffusion process in a solid phase and is in good agreement with prediction [12] for the diffusion of oxygen inside platinum at the experimental temperature of 450°C.…”

Section: Resultsmentioning

confidence: 99%

Charge storage at the Pt/YSZ interface

et al. 2007

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The electrochemical behavior of Pt/YSZ electrodes in oxygen containing atmosphere at 450°C has been investigated by double-step chronoamperometry and programmed linear sweep cyclic voltammetry. The response of the O 2 (g),Pt/YSZ system in these experiments could be separated into a time dependent and a steady state contribution, the former being dominated by pseudocapacitive processes. It is proposed that Pt-O type species were stored via different processes at three different locations in the O 2 (g),Pt/YSZ system: (1) Build-up of a platinum oxide monolayer at the Pt/YSZ binary interface. (2) Formation of Pt-O species at the triple phase boundary and their spreading-out along the Pt/gas interface. (3) Growth of the platinum oxide layer from the binary Pt/YSZ interface toward the bulk of the platinum electrode.

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“…4), also the increase in the area of the third voltammetric peak (N 3 ) follows t 1/2 h kinetics, suggesting again a diffusion mechanism [10]. Supposing that N 1 corresponds to the formation of an oxide monolayer at the Pt/YSZ interface and N 3 to the formation of multilayer, one can estimate the diffusion length L t at a given time from L t = d N 3 (t h ) / N 1 , where N 3 (t h ) is the amount of oxygen atoms in the multilayer at time t h , N 1 is the amount of oxygen atoms in the monolayer at the Pt/YSZ interface (6.6×10 14 atom) and d is the average thickness of an oxide layer (2.7×10 −10 m, estimated with the Pt-Pt atomic distance [14]). Knowing the diffusion length as a function of time, a diffusion coefficient of D = 3×10 −22 m 2 s −1 is calculated.…”

Section: /2mentioning

confidence: 99%

Charge storage at Pt/YSZ interface as the origin of `permanent' electrochemical promotion of catalysis

Fóti

2009

Per. Pol. Chem. Eng.

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Tuning of the catalytic reaction rate by electric polarization of the interface between an electron conducting catalyst and an ion conducting support, called electrochemical promotion of catalysis (EPOC), is most often fully reversible. Its stateof-the-art model regards the gas-exposed catalyst surface as the unique location of charge storage via backspillover of electrochemically generated species, responsible for promotion. After long-lasting anodic polarization, a permanent effect (P-EPOC) was observed in ethylene combustion with oxygen over Pt/YSZ catalyst. Double step chronoamperometric and linear sweep voltammetric analysis revealed delayed oxygen storage, located presumably at the vicinity of the catalyst/electrolyte interface. It is proposed that oxygen stored at this location, hence hidden for the reactants and then released during relaxation, was at the origin of the observed P-EPOC. The effect of this 'hidden' promoter on the catalytic reaction rate was found to be highly non Faradaic.

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Untitled

Cited by 62 publications

References 16 publications

Combined TPRx, in situ GISAXS and GIXAS studies of model semiconductor-supported platinum catalysts in the hydrogenation of ethene

Combined TPRx, in situ GISAXS and GIXAS studies of model semiconductor-supported platinum catalysts in the hydrogenation of ethene

Charge storage at the Pt/YSZ interface

Charge storage at Pt/YSZ interface as the origin of `permanent' electrochemical promotion of catalysis

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