Reactivity of Bimetallic Systems Studied from First Principles

Groß, Axel

doi:10.1007/s11244-006-0005-x

Cited by 192 publications

(122 citation statements)

References 70 publications

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“…Such sites have been determined by HREELS to exist in a model catalyst at the edge of Au islands on Pd(1 1 1) surface, responsible for CO ''linear'' adsorption [24]. Improvement in activity could then be considered from a positive combination between electronic and geometric effects [25]. It is important to observe that the balance between these two effects could be also modified by the support.…”

Section: Resultsmentioning

confidence: 99%

Single-phase gold/palladium catalyst: The nature of synergistic effect

et al. 2007

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The liquid phase oxidation of glycerol with oxygen has been studied using mono and bimetallic catalysts based on Au and Pd metals supported on activated carbon, in order to study the effect of the metal on the distribution of the products and on activity of catalysts. It was found that by using bimetallic catalysts (Au-Pd) a strong synergistic effect was shown. By using a preformed nucleating centre we were able to obtain a single alloyed phase, which allowed us to address the synergistic effect to the presence of alloyed Au/Pd. The advantage of using this latter catalyst lies not only in the high activity but also in a prolonged catalyst life. Although a partial leaching of palladium and assembling of the particles have been revealed by ICP and HRTEM respectively, activity after 10 re-cycles decreased less than expected (about 10%).

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Section: Resultsmentioning

confidence: 99%

Single-phase gold/palladium catalyst: The nature of synergistic effect

et al. 2007

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“…In addition, the risk of deactivation due to sintering is increased, particularly with supported catalysts. Another strategy that has proven useful for circumventing poisoning (whilst retaining reasonable activity) has been to alloy less reactive metals such as Cu, Ag and Au, with the PGMs; these coinage metals exhibit high tolerance to poisoning, albeit typically having reduced catalytic activity [5][6][7][8][9][10]. Generally, alloying in this manner quenches the affinity of the PGMs to CO, though it may also inhibit their activity [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Carbon Monoxide Poisoning Resistance and Structural Stability of Single Atom Alloys

et al. 2018

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Platinum group metals (PGMs) serve as highly active catalysts in a variety of heterogeneous chemical processes. Unfortunately, their high activity is accompanied by a high affinity for CO and thus, PGMs are susceptible to poisoning. Alloying PGMs with metals exhibiting lower affinity to CO could be an effective strategy toward preventing such poisoning. In this work, we use density functional theory to demonstrate this strategy, focusing on highly dilute alloys of PGMs (Pd, Pt, Rh, Ir and Ni) with poison resistant coinage metal hosts (Cu, Ag, Au), such that individual PGM atoms are dispersed at the atomic limit forming single atom alloys (SAAs). We show that compared to the pure metals, CO exhibits lower binding strength on the majority of SAAs studied, and we use kinetic Monte Carlo simulation to obtain relevant temperature programed desorption spectra, which are found to be in good agreement with experiments. Additionally, we consider the effects of CO adsorption on the structure of SAAs. We calculate segregation energies which are indicative of the stability of dopant atoms in the bulk compared to the surface layer, as well as aggregation energies to determine the stability of isolated surface dopant atoms compared to dimer and trimer configurations. Our calculations reveal that CO adsorption induces dopant atom segregation into the surface layer for all SAAs considered here, whereas aggregation and island formation may be promoted or inhibited depending on alloy constitution and CO coverage. This observation suggests the possibility of controlling ensemble effects in novel catalyst architectures through CO-induced aggregation and kinetic trapping.

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“…Those can be particle size, [1][2][3] particle dispersion, [4,5] density of low-coordinated surface atoms [6][7][8] and influence of the substrate material. [9][10][11][12][13][14][15][16][17][18] Fast transport due to spherical diffusion for small, isolated particles resulting from fine particle dispersion might also be an important parameter.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Reactivity for Hydrogen Reactions at Pt Nanoislands on Au(111)

2010

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We report high exchange current densities exceeding 1 A cm(-2) at Pt nanostructures on Au(111) for hydrogen-related reactions. Such activity is found at Pt nanoparticles with a coverage of less than 10 % of a monolayer on Au(111) and on single Pt particles deposited on Au(111). Potential pulse technique as well as micropolarization curves with overpotentials of +/-10 mV were used in the case of extended nanostructured surfaces to determine the activity. Single Pt particles were investigated in an in situ electrochemical scanning tunneling microscope setup using the STM tip as local sensor. The reactivity obtained on Pt nanostructured Au(111) towards hydrogen reactions were subsidized by single particle reactivity measurements. The specific activity of platinum is enhanced by more than a factor of 1000 as compared to a Pt(111) single crystal. Aspects that may explain this enhancement such as an involvement of the substrate, highly reactive defect sites and enhanced mass transport are discussed.

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Reactivity of Bimetallic Systems Studied from First Principles

Cited by 192 publications

References 70 publications

Single-phase gold/palladium catalyst: The nature of synergistic effect

Single-phase gold/palladium catalyst: The nature of synergistic effect

Carbon Monoxide Poisoning Resistance and Structural Stability of Single Atom Alloys

Enhanced Reactivity for Hydrogen Reactions at Pt Nanoislands on Au(111)

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