Pt-Sn/C as a possible methanol-tolerant cathode catalyst for DMFC

An effective method was developed for preparing highly dispersed nano-sized Pt–Sn/C electrocatalyst synthesised by a modified polyol reduction method. From XRD patterns, the Pt–Sn/C peaks shifted slightly to lower 2θ angles when compared with commercial Pt/C catalyst, suggesting that Sn formed alloy with Pt. Based on HR-TEM images, the Pt–Sn/C nanoparticles showed small particle sizes and well dispersed onto the carbon support with a narrow particle distribution. The methanol oxidation reaction on the as-prepared Pt–Sn/C catalyst appeared at lower currents (+7.08 mA at +480 mV vs. Ag/AgCl) compared to the commercial Pt/C (+8.25 mA at +480 mV vs. Ag/AgCl) suggesting that the Pt–Sn/C catalyst has ‘methanol tolerance capabilities’. Pt–Sn/C HA Slurry pH3 catalysts showed better activity towards the oxygen-reduction reaction (ORR) than commercial Pt/C which could be attributed to smaller particle sizes. In our study, the Pt–Sn/C catalyst appears to be a promising methanol-tolerant catalyst with activity towards the ORR in the DMFC.Web of Scienc

Fabrication of Pt/Ru Nanoparticle Pair Arrays with Controlled Separation and their Electrocatalytic Properties

Aiming at the investigation of spillover and transport effects in electrocatalytic reactions on bimetallic catalyst electrodes, we have prepared novel, nanostructured electrodes consisting of arrays of homogeneously distributed pairs of Pt and Ru nanodisks of uniform size and with controlled separation on planar glassy carbon substrates. The nanodisk arrays (disk diameter approximate to 60 nm) were fabricated by hole-mask colloidal lithography; the separation between pairs of Pt and Ru disks was varied from -25 nm (overlapping) via +25 nm to +50 nm. Morphology and (surface) composition of the Pt/Ru nanodisk arrays Were characterized by scanning electron microscopy, energy dispersive X-ray analysis, and X-ray Photoelectron spectroscopy, the electrochemical/electrocatalytic properties were explored by cyclic voltammetry, COad monolayer oxidation ("COad stripping"), and potentiodynamic hydrogen oxidation. Detailed analysis of the 2 COad oxidation peaks revealed that on all bimetallic pairs these cannot be reproduced by superposition of the peaks obtained on electrodes with Pt/Pt or Ru/Ru pairs, pointing to effective Pt-Ru interactions even between rather distant pairs (50 nm). Possible reasons for this observation and its relevance for the understanding of previous reports of highly active catalysts with separate Pt and Ru nanoparticles are discussed. The results clearly demonstrate that this preparation method is perfectly suited for fabrication of planar model electrodes with well-defined arrays of bimetallic nanodisk pairs, which opens up new possibilities for model studies of electrochemical/electrocatalytic reactions

Enhanced HER and ORR behavior on photodeposited Pt nanoparticles onto oxide-carbon composite

International audienceThe photodeposition process under ultraviolet domain for platinum nanoparticles was explored. The concomitant presence of different mechanisms during the photodeposition of Pt nanoparticles onto TiO2 in the presence of water and alcohol is evidenced. According to the process, one can devise various complex mechanisms. The presence of nanoparticulated oxide anatase phase enhances the photodeposition process of metal nanoparticles via the so-called heterogeneous photocatalysis. A description and the effect of mixing of various chemicals in the reactor reveal interesting information, which allows controlling the size of nanoparticles by the photodeposition process. This study also paves the way to decrease the amount of precious metals used in material composition used as catalysts towards hydrogen evolution reaction and oxygen reduction reaction for fuel cell technologies

Effect of Co substitution for Fe in Sr2FeMoO6 on electrocatalytic properties for oxygen reduction in alkaline medium

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The Functionalizing Effect of Increasingly Graphitic Carbon Supports on Carbon-Supported and TiO2-Carbon Composite-Supported Pt Nanoparticles.

International audienceStrong interaction between Pt nanoparticles and graphitic carbon in carbon-based and oxide–carbon composite substrates is demonstrated using electrochemical CO stripping experiments. A correlation between the in-plane crystallite size of the carbon supports and the oxidation charge of CO stripping wave was made. It appears that π-system of graphitized carbon anchors platinum particles in a way that strongly modifies the electronic properties of the Pt valence band. The effects of graphitized carbon on platinum are even observable on TiO2–carbon composite-supported Pt, where a well-known strong metal–support interaction between Pt and TiO2 is already present, demonstrating the significant extent of the interaction between Pt and graphite. Finally, a preliminary proof of the role played by the interfacial Pt–Ti nanoalloy on oxide–carbon composite is given

Towards Understanding the Essential Role Played by the Platinum-Support Interaction on Electrocatalytic Activity

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Structural and electrochemical studies of Pt-Sn nanoparticulate catalysts

Structural and stability studies of bimetallic Pt-Sn (3:1) nanoparticles were performed in situ via X-ray diffraction at wide angles (WAXS). The homemade bimetallic catalyst (Pt-Sn) ccomp (ccomp = from carbonyl complex) was synthesized in mild conditions from a Pt-carbonyl chemical precursor. A relatively narrow size distribution (2.4 ± 0.9 nm) of such a bimetallic catalyst supported onto carbon Vulcan XC72 was obtained at room temperature. Its electrochemical behavior was compared to that of a commercial catalyst. The WAXS study revealed that such a catalyst, prepared via the carbonyl route, has a certain degree of surface disorder (high Debye parameter, B), which enhances the electrocatalytic activity for hydrogen adsorption. Furthermore, WAXS also demonstrated that the structural stability of this bimetallic catalyst is maintained at the annealing temperature employed (500 C), although the particle size increases from 1.6 to 2.2 nm. Electrochemical underpotential deposition studies, via copper deposition, also provide information concerning the state of the nanoparticulate surface of the various platinum-based catalysts investigated

Mixed-oxide Ti1−xWxO2 as support for (photo)-electrochemical processes

Abstract In this study, mixed-oxides of Ti1−xWxO2 (0 ≤ x ≤ 0.3) nanomaterials have been synthesized via a multistep sol–gel process. The effect of W doping on the anatase structure and on the electrical conductivity of the material was investigated. Photo-electrochemical action spectra and UV–vis spectroscopy were used to determine the bang-gap energy of the mixed-oxides. The electrochemical stability of these materials was also investigated before they were tested as substrate for platinum nanocatalysts for oxygen reduction reaction. The metal was deposited onto the support either via the chemical route (carbonyl method) or via UV-irradiation