Effect of surface segregation on the catalytic activity of alloys: CO hydrogenation on Pd–Ni(111) surface

Khanra, Badal C.; Bertolini, J.C.; Rousset, Jean

doi:10.1016/s1381-1169(97)00150-7

Cited by 35 publications

(20 citation statements)

References 20 publications

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“…27,28 Exposure of the surface to gas appears to considerably affect the structure of the catalytic surface, influencing surface segregation and aggregation. 21,29,30 In consequence, adsorbate-induced structural changes have been the main focus of numerous theoretical and experimental studies, which have explored the effect of alloy surface exposure to number of gases (e.g. CO, H2, NO and O2) in the aim of improving the catalytic properties of the material.…”

Section: Introductionmentioning

confidence: 99%

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

2019

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Highly dilute binary alloys composed of an active platinum group metal (PGM) and a more inert coinage metal are important in the field of catalysis, as they function as active and selective catalysts. Their catalytic properties depend on the surface "ensemble" of PGM atoms, whose size may be altered under reactive conditions. We use density functional theory and investigate the interaction of CO, a molecule common in numerous industrially important chemistries, with alloys that are composed of a PGM (Pt, Pd, Rh, Ir, Ni) doped in coinage metal hosts (Cu, Au, Ag). We study the adsorption of CO on the (211) step and (100) facet and compare our results to those previously obtained on the (111) facet. We determine strong correlations between the adsorption energies of CO across the facets and highlight the corresponding thermochemical scaling relations. Finally, we study the stability of isolated surface dopant atoms with respect to aggregation into clusters and segregation into the bulk, both in the presence and absence of CO. We find that strong COdopant interactions significantly influence the morphology of the catalyst surface, suggesting that it may be possible to establish control over the ensemble size of the dopant by tuning PCO.

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Section: Introductionmentioning

confidence: 99%

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

2019

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“…All these features are dependent on the composition of an alloy, some of them on the entire bulk composition, and others on the surface composition, and are usually interrelated. Therefore, it is absolutely necessary to possess as much information as possible on the bulk and surface contents of the alloy components, which are often different, even in the case of homogeneous alloys [ 36 , 37 , 38 , 39 ]. The knowledge on the distribution of elements in the alloy bulk and on the surface, as well as the sample crystal structure, the degree of material homogeneity, or the presence of separate bulk/surface phases is also very important.…”

Section: Introductionmentioning

confidence: 99%

Comparative Physicochemical and Electrochemical Characterization of the Structure and Composition of Thin Pd Binary and Ternary Codeposits with Pt, Ru, and Rh

et al. 2018

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Pd-Ru, Pd-Rh, Pd-Pt-Ru, and Pd-Rh-Ru electrodes were prepared as thin layers by potentiostatic codeposition or chemical co-precipitation of metals from baths containing mixtures of chloride salts. The formation of substitutional solid solutions, with lattice parameters smaller than that of pure Pd, was confirmed by X-ray diffraction (XRD). The compositions at various levels of sample volume and thickness were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and also electrochemically by cyclic voltammetry (CV) in 0.5 M H2SO4. The differences between surface, subsurface, and bulk compositions were compared for various systems in a wide composition spectrum.

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“…One of the most appropriate adsorbate molecules for inducing surface segregation is carbon monoxide since it binds to metal atoms with varying strength. Indeed, there are a number of experimental and theoretical studies which report its use for this purpose with a variety of bimetallic systems including PdAu [8][9][10][11], PdNi [12], PdCu [13][14][15][16][17][18], NiCu [19] and PtCo [20] (note: in each case the metal listed first segregates towards the surface upon exposure to CO).…”

Section: Introductionmentioning

confidence: 99%

CO induced surface segregation as a means of improving surface composition and enhancing performance of CuPd bimetallic catalysts

McCue

Anderson

2015

Journal of Catalysis

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a b s t r a c tA series of copper rich CuPd/Al 2 O 3 catalysts were prepared and characterised by FTIR spectroscopy using CO as a probe molecule. After reduction, the surface composition was largely composed of Cu with evidence of a small concentration of isolated Pd atoms. It was found that CO induced surface segregation could be used to increase the surface Pd concentration and depending on the Cu:Pd ratio, the formation of Pd-Pd dimers was possible. Changes in surface composition were quantified and correlated with catalyst activity and selectivity for selective acetylene hydrogenation. For the catalyst with optimum Cu:Pd ratio (50:1), it was possible to use CO induced segregation to increase activity considerably (20 K temperature reduction to achieve 100% conversion) whilst only marginally affecting ethylene selectivity (%5% decrease in ethylene selectivity). An estimate of the detection limit by FTIR of the minimum surface coverage of isolated Pd and Pd-Pd dimers is given.

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Effect of surface segregation on the catalytic activity of alloys: CO hydrogenation on Pd–Ni(111) surface

Cited by 35 publications

References 20 publications

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

Comparative Physicochemical and Electrochemical Characterization of the Structure and Composition of Thin Pd Binary and Ternary Codeposits with Pt, Ru, and Rh

CO induced surface segregation as a means of improving surface composition and enhancing performance of CuPd bimetallic catalysts

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