Experimental determination of equilibrium surface segregation in Pt-Ni single crystal alloys

Temmerman, Leen De; Creemers, C.; Hove, H. Van; Neyens, A.; Bertolini, J.C.; Massardier, J.

doi:10.1016/0167-2584(86)90213-6

Cited by 3 publications

(3 citation statements)

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“…A few particles however present a Ni-rich core (Figure 2d), which is consistent with the presence of a few Ptenriched alloy nanoparticles that may have been formed upon beam exposure. Pt−surface segregation has indeed been reported for thermally treated Ni−Pt alloys 68 and Pt-rich Ni−Pt nanoalloys. 69 However, in most cases, Pt and Ni atoms seem randomly located inside the particle, in a real Ni−Pt solid solution, despite the higher surface energy and smaller atom size of Ni.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 63%

One-Pot Synthesis of Size- and Composition-Controlled Ni-Rich NiPt Alloy Nanoparticles in a Reverse Microemulsion System and Their Application

Biausque

Laveille

Anjum

et al. 2017

ACS Appl. Mater. Interfaces

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Bimetallic nanoparticles have been the subject of numerous research studies in the nanotechnology field, in particular for catalytic applications. Control of the size, morphology, and composition has become a key challenge due to the relationship between these parameters and the catalytic behavior of the particles in terms of activity, selectivity, and stability. Here, we present a one-pot air synthesis of 2 nm NiPt nanoparticles with a narrow size distribution. Control of the size and composition of the alloy particles is achieved at ambient temperature, in the aqueous phase, by the simultaneous reduction of nickel and platinum precursors with hydrazine, using a reverse microemulsion system. After deposition on an alumina support, this Ni-rich nanoalloy exhibits unprecedented stability under the harsh conditions of methane dry reforming.

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Section: Acs Applied Materials and Interfacesmentioning

confidence: 63%

One-Pot Synthesis of Size- and Composition-Controlled Ni-Rich NiPt Alloy Nanoparticles in a Reverse Microemulsion System and Their Application

Biausque

Laveille

Anjum

et al. 2017

ACS Appl. Mater. Interfaces

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“…% on the surface in Pt 78 Ni 22 (111) has been measured to be about 97 at. % at 760 K using ISS 54 and about 99 ± 1 at. % at 1170 K using LEED.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Development of a ReaxFF Reactive Force Field for the Pt–Ni Alloy Catalyst

et al. 2016

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We developed the ReaxFF force field for Pt/Ni/C/H/O interactions, specifically targeted for heterogeneous catalysis application of the Pt-Ni alloy. The force field is trained using the DFT data for equations of state of PtNi, PtNi and PtNi alloys, the surface energy of the PtNi(111) (x = 0.67-0.83), and binding energies of various atomic and molecular species (O, H, C, CH, CH, CH, CO, OH, and HO) on these surfaces. The ReaxFF force field shows a Pt surface segregation at x ≥ 0.67 for the (111) surface and x ≥ 0.62 for the (100) surface in vacuum. In addition, from the investigation of the preferential alloy component of the adsorbates, it is expected that H and CH on the alloy surface to induce a segregation of Pt whereas the oxidation intermediates and products such as C, O, OH, HO, CO, CH, and CH are found to induce Ni segregation. The relative order of binding strengths among adsorbates is a function of alloy composition and the force field is trained to describe the trend observed in DFT calculations, namely, H < HO < CH ≈ O ≈ CO < OH < CH < C ≈ CH on PtNi, H < HO < CO < O ≈ CH < OH < CH < CH < C on PtNi, and H < HO < O < CO < CH < OH < CH < C ≈ CH on PtNi. Using this force field, we performed the grand-canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations for a PtNi slab and a truncated cuboctahedral nanoparticle terminated by (111) and (100) faces, to examine the surface segregation trend under different gas environments. It is found that Pt segregates to the alloy surface when the surface is exposed to vacuum and/or H environment while Ni segregates under the O environment. These results suggest that the Pt/Ni alloy force field can be successfully used for the preparation of Pt-Ni nanobimetallic catalysts structure using GCMC and run MD simulations to investigate its role and the catalytic chemistry in catalytic oxidation, dehydrogenation and coupling reactions. The current Pt/Ni force field still is found to have difficulties in describing the observed segregation trend in Ni-rich alloy compositions (x < 0.6), suggesting the need for additional force field training and evaluation for its application to describe the characteristics and chemistry of Ni-rich alloys.

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“…Platinum segregates on Pt‐Ni alloy surfaces. The surface composition of Pt‐Ni alloys was assessed by ion scattering spectroscopy, and platinum was found to be the segregating component . The surface of Pt‐Ni alloys at 452°C was strongly enriched in Pt: 37, 96, and 99 at% for Pt 10 Ni 90 , Pt 50 Ni 50 , and Pt 78 Ni 22 bulk compositions, respectively.…”

Section: Crystal Structure and Surface Segregation Of Pt‐ni Alloysmentioning

confidence: 99%

The oxygen reduction on Pt-Ni and Pt-Ni-M catalysts for low-temperature acidic fuel cells: A review

Antolini¹

2018

Int J Energy Res

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Summary For its wide availability and low cost, nickel is a promising candidate to be used as a cocatalyst in Pt‐based catalysts for proton exchange membrane fuel cells. Among Pt‐M (M = transition metal) catalysts for oxygen reduction, Pt‐Ni is the one which can be used in various forms, that is, as disordered Pt1‐xNix solid solutions, ordered intermetallic phases, octahedral‐shaped structures (with a preferential {111} facet orientation), dealloyed structures, and hollow and 1‐dimensional nanostructures. In this work, an overview of the oxygen reduction on Pt‐Ni and Pt‐Ni‐M (M = Co, Fe, Cu) catalysts and their stability in proton exchange membrane fuel cell environment is presented.

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Experimental determination of equilibrium surface segregation in Pt-Ni single crystal alloys

Cited by 3 publications

References 0 publications

One-Pot Synthesis of Size- and Composition-Controlled Ni-Rich NiPt Alloy Nanoparticles in a Reverse Microemulsion System and Their Application

One-Pot Synthesis of Size- and Composition-Controlled Ni-Rich NiPt Alloy Nanoparticles in a Reverse Microemulsion System and Their Application

Development of a ReaxFF Reactive Force Field for the Pt–Ni Alloy Catalyst

The oxygen reduction on Pt-Ni and Pt-Ni-M catalysts for low-temperature acidic fuel cells: A review

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