Carbon Support Effects on Bimetallic Pt−Ru Nanoparticles Formed from Molecular Precursors

Abstract

We describe the preparation, structural characterization, and support interactions experienced by two different compositions of Pt−Ru nanoparticles supported on several carbons (carbon black, fullerene soot, and desulfurized carbon black). The bimetallic nanoparticles, obtained by reduction of the neutral molecular precursors PtRu5C(CO)16 and Pt2Ru4(CO)18 (the latter of which lacks a central “stabilizing” carbide core) at elevated temperatures in a hydrogen atmosphere, show a structural homology, exhibiting exceptionally narrow size and compositional distributions. A detailed structural picture of the nanoparticles has been deduced on the basis of in-situ extended X-ray absorption fine structure (EXAFS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray analysis (EDX), and X-ray absorption near edge structure (XANES). These techniques reveal that the bimetallic nanoparticles have Pt/Ru compositions of 1:5 and 2:4, respectively, and average diameters lying between 1.0 and 1.5 nm. The local metal coordination environments reveal a nonstatistical distribution of the two metals in the nanoparticles. Specifically, Pt shows a marked preference for segregation to the particle surfaces under an H2 atmosphere. The data also reveal a difference in the structural environment of the nanoparticles when formed on the fullerene soot support. Interactions between Ru and low-Z atoms are revealed through XANES, which, taken collectively with the other data presented, leads us to propose a possible Ru−C compound formation on this latter support phase.

Anchoring of Ru–Pt and Ru–Au Clusters onto a Phosphane‐Functionalized Carbon Support

“…(PPN) 2 [Ru 6 C(CO) 16 ] and (PPN) 2 [Ru 5 C(CO) 14 ] were synthesized as described previously. [19] [Pt(COD)Cl 2 ], [Au(PPh 3 )Cl] and H 2 CO were supplied by Sigma-Aldrich, H 2 NC 3 H 7 by Acros Organics, HPPh 2 by Fluka, and all were used as received.…”

“…Cluster 2, which is also known, [20] was prepared here by a new, easier route from (PPN) 2 [Ru 6 C(CO) 16 ] and Au(PPh 3 )Cl. Both clusters (Scheme 1) were unambiguously identified by their IR spectra.…”

“…The reaction mixture was separated by column chromatography to give three different products. The first product isolated corresponds to the cluster [Ru 5 PtC(CO) 16 ] previously described in the literature and very often isolated from reactions involving 1. [24] The second isolated product displayed CO stretching bands at 2068, 2029 and 2019 cm -1 , attributable to terminal carbonyl ligands.…”

Methanol Electro-Oxidation on Pt-Ru Alloy Nanoparticles Supported on Carbon Nanotubes

“…However, the CNT catalyst support could be an important factor affecting the catalyst activity due to metal-support interactions. In a previous study, fullerene soot and carbon black were found to have different interactions with the Pt/Ru catalysts [48] due to their different surface structures. Although the enhancement from the metal-carbon support interactions toward methanol electro-oxidation is not fully understood, we believe that the CNTs, which have a curved graphitic surface, could promote the PtRu activity.…”

Particle growth behavior of carbon-supported Pt, Ru, PtRu catalysts prepared by an impregnation reductive-pyrolysis method for direct methanol fuel cell anodes

“…The delicate control of composition, particle size, and dispersion state are only a few of the requirements for practical catalysts. The co-impregnation method [13][14][15][16][17][18][19][52][53][54][55][56][57][58][59][60][61] is a simple and effective method for the preparation of high surface area carbon supported electrocatalysts. We have shown that the structural properties and electrocatalysis of carbon supported PtRu nanoparticles 3 JCAT04-486 revised W. Sugimoto et al vary with the type of precursor employed, and the activity towards methanol electro-oxidation is sensitive to the pyrolysis temperature [14].…”