Colloidal Synthesis of Ni<sub>x</sub>Pt<sub>1−x</sub> Nanoparticles with Tuneable Composition and Size

Ahrenstorf, Kirsten; Albrecht, Ole; Heller, Hauke; Kornowski, Andreas; Görlitz, Detlef; Weller, Horst

doi:10.1002/smll.200600486

Cited by 111 publications

(133 citation statements)

References 19 publications

(14 reference statements)

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“…1 for the NiPt-CNT system after 1 and 10 minutes of reaction. As reported for the particle synthesis in homogeneous solution the particle formation is fast and the reaction is usually finished within a few minutes after the injection of the platinum precursor [20,32,[38][39][40]. Accordingly, we find a large amount of small particles either freely in solution or covering the CNTs already after 1 minute of synthesis.…”

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confidence: 76%

“…Recent reports include platinum [6,8,9] [19,20] and catalytic properties [21][22][23]. Beyond that, 1D alignment of NPs enables to modify the saturation magnetization and coercitivity through magnetostatic coupling [24][25][26].…”

mentioning

confidence: 99%

“…A convenient way for 1D alignment is the attachment of NPs to CNTs, which is usually achieved by electrochemical deposition [27,28], the reduction of metallic salts in the presence of functionalized CNTs [15,29], or chemical vapor deposition [10], among others [30]. On the other hand, concerning the NP synthesis, the organometallic synthesis route provides nanocrystalline alloyed materials with precise size control and tunable composition in several systems [20,31,32]. Here, we report on the synthesis of alloyed N i x P t 1−x [20], Co x P t 1−x and F e x P t 1−x [32] NPs as well as pure P t [33] NPs and their attachment to non-functionalized singlewall (SWCNTs), multiwall carbon nanotubes (MWCNTs) and glassy carbon by their simple integration in the organometallic synthesis.…”

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Reversible Attachment of Platinum Alloy Nanoparticles to Nonfunctionalized Carbon Nanotubes

et al. 2010

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The formation of monodisperse, tunable sized, alloyed nanoparticles of Ni, Co, or Fe with Pt and pure Pt nanoparticles attached to carbon nanotubes has been investigated. Following homogeneous nucleation, nanoparticles attach directly to non-functionalized singlewall and multiwall carbon nanotubes during nanoparticle synthesis as a function of ligand nature and the nanoparticle work function. These ligands do not only provide a way to tune the chemical composition, size and shape of the nanoparticles but also control a strong reversible interaction with carbon nanotubes and permit controlling the nanoparticle coverage. Raman spectroscopy reveals that the sp2 hybridization of the carbon lattice is not modified by the attachment. In order to better understand the interaction between the directly attached nanoparticles and the non-functionalized carbon nanotubes we employed first-principles calculations on model systems of small Pt clusters and both zig-zag and armchair singlewall carbon nanotubes. The detailed comprehension of such systems is of major importance since they find applications in catalysis and energy storage.Composites of metallic nanoparticles (NPs) and carbon nanotubes (CNTs) exhibit high catalytic activity for various chemical reactions [1][2][3][4][5][6] and have also been explored for hydrogen storage applications [7]. Recent reports include platinum [6,8,9] [19,20] and catalytic properties [21][22][23]. Beyond that, 1D alignment of NPs enables to modify the saturation magnetization and coercitivity through magnetostatic coupling [24][25][26]. A convenient way for 1D alignment is the attachment of NPs to CNTs, which is usually achieved by electrochemical deposition [27,28], the reduction of metallic salts in the presence of functionalized CNTs [15,29], or chemical vapor deposition [10], among others [30]. On the other hand, concerning the NP synthesis, the organometallic synthesis route provides nanocrystalline alloyed materials with precise size control and tunable composition in several systems [20,31,32]. Here, we report on the synthesis of alloyed N i x P t 1−x [20], Co x P t 1−x and F e x P t 1−x [32] NPs as well as pure P t [33] NPs and their attachment to non-functionalized singlewall (SWCNTs), multiwall carbon nanotubes (MWCNTs) and glassy carbon by their simple integration in the organometallic synthesis. The experimental procedure involves only a single synthetic step, whereby the crucial parameter for attachment was found in the correct balance of the ligands oleylamine (OA) and oleic acid (Oac).

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Reversible Attachment of Platinum Alloy Nanoparticles to Nonfunctionalized Carbon Nanotubes

et al. 2010

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“…The XRD pattern of the free-standing PtCo nanocrystals exhibits reflections characteristic of a facecentered cubic (fcc) lattice shifted to slightly higher angles (ϩ0.1°) than those expected for bulk Pt, which is consistent with a change in lattice constant due to alloy formation. 2,25 The peaks observed at 16 and 24°are artifacts of the XRF tape used in data acquisition. Selected area energy-dispersive X-ray spectroscopy (EDX) analysis performed on single free-standing particles gives an average of 15% (atomic) Co incorporation relative to Pt, while the change in lattice constant by XRD corresponds to about 5% Co incorporation.…”

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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“…One branch of material synthesis which fulfills these requirements is colloidal chemistry [33]. Today, the control over nucleation and growth phases of nanocrystals allows tayloring the crystal size, while the amount and nature of ligand molecules and precursors permits control over shape, surface properties, and atomic composition of the nanocrystals [34]. In some systems it is possible to synthesize such structures with almost atomic precision and in macroscopic amounts [35,36].…”

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Metal nanoparticle field-effect transistor

Cai

Michels

Bachmann

et al. 2013

Journal of Applied Physics

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We demonstrate that by means of a local top-gate current oscillations can be observed in extended, monolayered films assembled from monodisperse metal nanocrystals -realizing transistor function. The oscillations in this metal-based system are due to the occurrence of a Coulomb energy gap in the nanocrystals which is tunable via the nanocrystal size. The nanocrystal assembly by the Langmuir-Blodgett method yields homogeneous monolayered films over vast areas. The dielectric oxide layer protects the metal nanocrystal field-effect transistors from oxidation and leads to stable function for months. The transistor function can be reached due to the high monodispersity of the nanocrystals and the high super-crystallinity of the assembled films. Due to the fact that the film consists of only one monolayer of nanocrystals and all nanocrystals are simultaneously in the state of Coulomb blockade the energy levels can be influenced efficiently (limited screening).

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Colloidal Synthesis of Ni_xPt_1−x Nanoparticles with Tuneable Composition and Size

Cited by 111 publications

References 19 publications

Reversible Attachment of Platinum Alloy Nanoparticles to Nonfunctionalized Carbon Nanotubes

Reversible Attachment of Platinum Alloy Nanoparticles to Nonfunctionalized Carbon Nanotubes

Probing Compositional Variation within Hybrid Nanostructures

Metal nanoparticle field-effect transistor

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Colloidal Synthesis of NixPt1−x Nanoparticles with Tuneable Composition and Size

Cited by 111 publications

References 19 publications

Reversible Attachment of Platinum Alloy Nanoparticles to Nonfunctionalized Carbon Nanotubes

Reversible Attachment of Platinum Alloy Nanoparticles to Nonfunctionalized Carbon Nanotubes

Probing Compositional Variation within Hybrid Nanostructures

Metal nanoparticle field-effect transistor

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Colloidal Synthesis of Ni_xPt_1−x Nanoparticles with Tuneable Composition and Size