Nucleation and Growth Mechanism of Ni<sub>x</sub>Pt<sub>1-x</sub>Nanoparticles

Ahrenstorf, Kirsten; Heller, Hauke; Kornowski, Andreas; Broekaert, J. A. C.; Weller, Horst

doi:10.1002/adfm.200800642

Cited by 78 publications

(91 citation statements)

References 24 publications

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“…6 In the case of NiPt nanocrystals prepared by Weller and coworkers, increasing the amount of Ni(OAc) 2 added prior to reaction favors growth rather than nucleation, indicating that Pt-rich nuclei are formed at the outset of reaction. 27 Therefore, the growth of bimetallic nanoparticles in our hybrid structures may be initiated by nucleation of Pt on the tips of the CdS rod, not only as a consequence of the high surface energy at the tips and the decreased activation energy for heterogeneous nucleation but also due to the high affinity between Pt and S. As growth continues, favorable free energy of mixing promotes incorporation of Co into the metal lattice to form an alloy. The lack of shift in the Bragg peaks predicted by Vegard's law may not necessarily preclude the presence of a PtCo alloy but may be a consequence of strain induced by the growth of the alloy on a Pt nucleate immobilized on a CdS nanorod.…”

Section: Resultsmentioning

confidence: 99%

Probing Compositional Variation within Hybrid Nanostructures

et al. 2009

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Ќ These authors contributed equally to this work. P latinum-based bimetallic alloys are highly desirable for their potential in magnetic storage, sensing, and catalysis, 1Ϫ5 often displaying properties that are independent of their constituent materials. 6 In addition to changes in the geometric distribution of the individual atoms, the unique structure and bonding in bimetallics can also lead to alterations in the electronic structure of the material. For example, PtNi alloys show enhanced activity for oxygen reduction relative to pure Pt, 7 as do similar alloys, including Pt 3 Co.8 However, bimetallic nanomaterials are not as well-understood outside of singlecrystalline studies or theoretical modeling, and the practical application of more complex nanostructures is further complicated by factors such as varied growth conditions, the presence of surface stabilizing agents, and the increased surface-to-volume ratio of nanoscale materials. Bimetallic nanoparticles have even been shown to undergo dynamic metal segregation in response to oxidizing or reducing environments. 9As nanostructured systems increase in complexity, the potential for structural and compositional variations with respect to the individual components rises dramatically. Hybrid nanostructures, the combination of two or more nanoscale materials to form a new heterostructure, are being actively pursued for a number of applications, 10 including device integration and assembly, 11Ϫ13 chemical and biological sensing, 14,15 and photocatalysis. 16Ϫ23 In particular, the integration of a metallic component with an optically active semiconductor, directly in solution, can lead to novel materials that exhibit new functionalities that result from the coupling between the individual components. For example, photocatalytic heterostructures can promote efficient charge separation across a metalϪsemiconductor junction, followed by catalytic reaction at the surface of the metal component.The development of semiconductorϪ metal hybrid nanostructures for magnetic and catalytic applications requires a thorough understanding of the metallic structure, which is difficult to predict for a complex system where nucleation and growth proceeds on the tip of a semiconductor. In a previous communication, we reported the selective growth of Pt, PtCo, and PtNi nanoparticles on the tips of CdS rods in solution. 24 Here, we present a detailed analysis of the structural and magnetic properties of PtCoϪCdS hybrid structures in comparison to similar free-standing PtCo nanoparticles. X-ray absorption spectroscopy (XAS) is utilized as a sensitive probe for identifying subtle differences in the local structure and composition of the hybrid materials, which can be difficult to discern using traditional analytical methods such as electron microscopy and X-ray diffraction (XRD). While the electronic and atomic structures of noble metal-based bimetallic alloys and free-standing PtCo

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Section: Resultsmentioning

confidence: 99%

Probing Compositional Variation within Hybrid Nanostructures

et al. 2009

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“…The PXRD pattern of the products displays the distinct face-center-cubic (fcc) pattern associated with Pt 3 Ni, being in agreement with that of the previous report. [ 38 ] The Pt/Ni composition is 74.2 ± 0.3/25.8 ± 0.3, as confi rmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and TEM energy-dispersive X-ray spectroscopy (TEM-EDS, 73.9 ± 0.5/26.1 ± 0.5) (Figure 1 g). The alloyed nanostructure was confi rmed by the STEM-EDS elemental mapping analysis, where the distribution of Pt and Ni is high even through the analyzed area (Figure 1 h).…”

Section: Communicationmentioning

confidence: 97%

A General Method for Multimetallic Platinum Alloy Nanowires as Highly Active and Stable Oxygen Reduction Catalysts

et al. 2015

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An unconventional class of high-performance Pt alloy multimetallic nanowires (NWs) is produced by a general method. The obtained PtNi NWs exhibit amazingly specific and mass oxygen reduction reaction (ORR) activities with improvement factors of 51.1 and 34.6 over commercial Pt/C catalysts, respectively, and are also stable in ORR conditions, making them among the most efficient electrocatalysts for ORR.

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“…170 As a result, the precious metal is prone to nucleate first and grow into separate nanoparticles or form Pt-rich regions in the product. 179,180 In fact, multiple factors can affect the size of Pt-alloy nanoparticles formed in solution during the crystal nucleation and growth process. In the synthesis of carbon-supported Ptalloy nanoparticles, nucleation can be induced by increasing temperature, adding a precursor, and adding a secondary metal precursor.…”

Section: Impact Of Pt-alloy Composition On Orr Activitymentioning

confidence: 99%

Carbon-Supported Pt-Based Alloy Electrocatalysts for the Oxygen Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells: Particle Size, Shape, and Composition Manipulation and Their Impact to Activity

Zhao²,

et al. 2015

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Nucleation and Growth Mechanism of Ni_xPt_1-xNanoparticles

Cited by 78 publications

References 24 publications

Probing Compositional Variation within Hybrid Nanostructures

Probing Compositional Variation within Hybrid Nanostructures

A General Method for Multimetallic Platinum Alloy Nanowires as Highly Active and Stable Oxygen Reduction Catalysts

Carbon-Supported Pt-Based Alloy Electrocatalysts for the Oxygen Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells: Particle Size, Shape, and Composition Manipulation and Their Impact to Activity

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Nucleation and Growth Mechanism of NixPt1-xNanoparticles

Cited by 78 publications

References 24 publications

Probing Compositional Variation within Hybrid Nanostructures

Probing Compositional Variation within Hybrid Nanostructures

A General Method for Multimetallic Platinum Alloy Nanowires as Highly Active and Stable Oxygen Reduction Catalysts

Carbon-Supported Pt-Based Alloy Electrocatalysts for the Oxygen Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells: Particle Size, Shape, and Composition Manipulation and Their Impact to Activity

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Nucleation and Growth Mechanism of Ni_xPt_1-xNanoparticles