Segregation at the surfaces of CuxPd1−x alloys in the presence of adsorbed S

Miller, James B.; Priyadarshini, Deepika; Gellman, Andrew J.

doi:10.1016/j.susc.2012.05.020

Cited by 14 publications

(12 citation statements)

References 57 publications

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“…The surface composition is described by the Langmuir-McLean expression at thermodynamic equilibrium. [ 31,44 ] Consider this situation: heating the AB alloy results in A surface segregation and the atomic A surface fraction increases with increasing temperature until thermodynamic equilibrium is reached. Color-coded matrix of segregation energies for impurities in 55-atom NPs composed of 12 late-transition metals.…”

Section: The Theories Of Surface Segregationmentioning

confidence: 99%

Surface Segregation in Bimetallic Nanoparticles: A Critical Issue in Electrocatalyst Engineering

Liao

Fisher

2015

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234

189

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Bimetallic nanoparticles are a class of important electrocatalyst. They exhibit a synergistic effect that critically depends on the surface composition, which determines the surface properties and the adsorption/desorption behavior of the reactants and intermediates during catalysis. The surface composition can be varied, as nanoparticles are exposed to certain environments through surface segregation. Thermodynamically, this is caused by a difference in surface energy between the two metals. It may lead to the enrichment of one metal on the surface and the other in the core. The external conditions that influence the surface energy may lead to the variation of the thermodynamic steady state of the particle surface and, thus, offer a chance to vary the surface composition. In this review, the most recent and important progress in surface segregation of bimetallic nanoparticles and its impact in electrocatalysis are introduced. Typical segregation inducements and surface characterization techniques are discussed in detail. It is concluded that surface segregation is a critical issue when designing bimetallic catalysts. It is necessary to explore methods to control it and utilize it as a way towards producing robust, bimetallic electrocatalysts.

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Section: The Theories Of Surface Segregationmentioning

confidence: 99%

Surface Segregation in Bimetallic Nanoparticles: A Critical Issue in Electrocatalyst Engineering

Liao

Fisher

2015

Small

234

189

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“…25 An identical sister tool will be attached to an apparatus for spatially resolved XPS/UPS/LEIS, to enable high throughput study of alloy surface phenomena such as segregation. 25,30 Finally, when coupled to a 10 Â 10 multichannel microreactor array, these CSAFs will enable rapid study of alloy catalysis across composition space. In general, well characterized CSAFs of the type described can be used to accelerate the study of number bulk and surface phenomena.…”

Section: Assessment Of the Rsm-csaf Deposition Toolmentioning

confidence: 99%

Apparatus for deposition of composition spread alloy films: The rotatable shadow mask

Fleutot¹,

Miller²,

Gellman³

2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Composition spread alloy films (CSAFs) are materials libraries used for high throughput investigations of multicomponent materials such as alloys, AxByC1−x−y. CSAFs are prepared such that the alloy film has a lateral spatial gradient in its local composition; thus, they include a set of alloy samples with a distribution of compositions that spans a continuous region of composition space (x,y). A tool based on the shadow mask concept has been developed for generating composition gradients, but modified to allow rotation of the shadow mask during CSAF deposition. The tool allows deposition of CSAFs containing up to four elements with rotatable shadow masks between each of the four electron beam evaporation sources and the deposition substrate. This allows codeposition of any combination of up to four components. In the case of the ternary AxByC1−x−y CSAFs, the three components can be deposited such that the resulting CSAF spans the entire ternary alloy composition space (x = 0 → 1, y = 0 → 1 − x) and, furthermore, contains all three binary alloys AxB1−x, AxC1−x, and BxC1−x (x = 0 → 1) and all three pure components. The innovation of the rotatable shadow masks also allows preparation of CSAFs that magnify selected regions of the composition space (x = xmin → xmax, y = ymin → 1 − x). Herein, we describe the design and performance of this new CSAF deposition tool and assess its merits and limitations with respect to other methods for CSAF preparation.

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“…In addition, it is also possible that Pd segregation and antisegregation might be driven by the changing enthalpy and entropy of the system. In a recent study it was found that for a Cu x Pd 1Àx alloy, Cu segregation to the surface in a clean alloy system is exothermic while Pd segregates in presence of adsorbed S and Cu segregation in presence of S is entropy driven [45]. Yet further research is required to establish the actual fact.…”

Section: Mechanism Of Formation Of Pdmo Core Shell Like Structuresmentioning

confidence: 99%

Core shell like behavior of PdMo nanoparticles on multiwall carbon nanotubes and their methanol oxidation activity in alkaline medium

Kakati

Maiti

Lee

et al. 2012

International Journal of Hydrogen Energy

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Segregation at the surfaces of CuxPd1−x alloys in the presence of adsorbed S

Abstract: The influence of adsorbed S on surface segregation in Cu x Pd 1-x alloys (S/Cu x Pd 1-x ) was characterized over a wide range of bulk alloy compositions (x = 0.05 to 0.95) using highthroughput Composition Spread Alloy Film (CSAF) sample libraries. Top-surface and near-

Cited by 14 publications

References 57 publications

Surface Segregation in Bimetallic Nanoparticles: A Critical Issue in Electrocatalyst Engineering

Surface Segregation in Bimetallic Nanoparticles: A Critical Issue in Electrocatalyst Engineering

Apparatus for deposition of composition spread alloy films: The rotatable shadow mask

Core shell like behavior of PdMo nanoparticles on multiwall carbon nanotubes and their methanol oxidation activity in alkaline medium

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