Size-Dependent Electrocatalytic Activity of Free Gold Nanoparticles for the Glucose Oxidation Reaction

International audienceUnderstanding the fundamental relationship between the size and the structure of electrode materials is essential to design catalysts and enhance their activity. Therefore, spherical gold nanoparticles (GNSs) with a mean diameter from 4 to 15 nm were synthesized. UV/Vis spectroscopy, transmission electron microscopy, and under-potential deposition of lead (UPDPb) were used to determine the morphology, size, and surface crystallographic structure of the GNSs. The UPDPbrevealed that their crystallographic facets are affected by their size and the growth process. The catalytic properties of these GNSs toward glucose electrooxidation were studied by cyclic voltammetry, taking into account the scan rate and temperature effects. The results clearly show the size-dependent electrocatalytic activity for glucose oxidation reactions that are controlled by diffusion. Small GNSs with an average size of 4.2 nm exhibited high catalytic activity. This drastic increase in activity results from the high specific area and reactivity of the surface electrons induced by their small size. The reaction mechanism was investigated by in situ Fourier transform infrared reflectance spectroscopy. Gluconolactone and gluconate were identified as the intermediate and the final reaction product, respectively, of the glucose electrooxidation

Activity of PtSnRh/C nanoparticles for the electrooxidation of C1 and C2 alcohols

International audienceA systematic investigation of alcohol adsorption and oxidation on binary and ternary electrocatalysts in acid medium was performed. Binary (PtRh) and ternary (PtRhSn) were prepared by the Pechini modified method on carbon Vulcan XC-72, and different nominal compositions were characterized by energy dispersive X-ray and X-ray diffraction (XRD) techniques. The XRD results showed that the Pt80Rh20/C and Pt70Sn10Rh20/C electrocatalysts consisted of the Pt displaced phase, suggesting the formation of a solid solution between the metals Pt/Rh and Pt/Sn. Electrochemical investigations on these different electrode materials were carried out as a function of the electrocatalyst composition, in acidmedium(0.5 mol dm(-3) H2SO4), and in the absence and presence of different alcohols (methanol, ethanol and ethylene glycol). The electrochemical results obtained at room temperature have shown that the Pt70Sn10Rh20/C catalyst display better catalytic activity for alcohol oxidation compared with the binary catalyst

Electrochemical oxidation of isopropanol using a nickel foam electrode

International audienceIn this study, a nickel foam electrode is used for the anodic conversion of isopropanol to acetone. The process is studied under well-defined experimental conditions including variation of the concentration of isopropanol, variation in the strength of the supporting electrolyte (aqueous KOH), different cyclic voltammetry scan rates, and different temperatures. The outcome of these experiments demonstrates that the isopropanol oxidation reaction is dependent on the presence of the beta-NiOOH surface species, which is generated at potentials near the potential of the isopropanol oxidation reaction. However, the two processes do not occur at the exact same potential and their respective behaviors under the various experimental conditions can be understood independently. Nickel foams are successfully applied as the anode material for controlled-potential electrolysis of isopropanol to form acetone. The Ni foam anode sustains a current density of 2.6 mA cm(-2) for the electrolysis time of 600 min without significant loss of activity. Isopropanol is converted to acetone at a rate of 5.6 mM per hour

Insight on the Surface Structure Effect of Free Gold Nanorods on Glucose Electrooxidation

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Electrochemical Behavior of Organics Oxidation on Palladium-Based Nanocatalysts Synthesized from Bromide Anion Exchange

International audiencePalladium-based and gold nanomaterials were synthesized by the so-called "Bromide Anion Exchange" method. This soft and clean synthetic route leads to well dispersed small nanoparticles on carbon support. Accordingly, these nanoscale structures have a high active surface area like 81 m(2) g(-1) for the 20 wt.% Pd/C electrocatalyst. The CO stripping experiments performed in alkaline medium have highlighted the dependence of the CO adsorption mode on palladium. When used as anode for glycerol or glucose electrooxidation in alkaline medium, they exhibit good activities. Moreover, the bimetallic catalysts showed an important improvement of the kinetics at lower potentials when compared to Pd/C. Some added value products like glycerate or glycolate have been detected by chromatographic analysis. These nanomaterials are promising electrodes in fuel or hybrid biofuel cell devices in a cogeneration of high value chemicals and energy process

Effect of Adding a Third Metal to Carbon-Supported PtSn-Based Nanocatalysts for Direct Ethanol Fuel Cell in Acidic Medium

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Synthesis of Gold-Platinum Nanomaterials Using Bromide Anion Exchange-Synergistic Electroactivity toward CO and Glucose Oxidation

International audienceBromide anion exchange, a method that consists of the introduction of KBr before the reduction of precursor salts by sodium borohydride, has enabled the synthesis of AuPt nanoparticles. Physicochemical techniques have been used to analyze these carbon Vulcan-modified catalytic powders that exhibit face-centered cubic structures. The powders of the bimetallic materials were mainly composed of solid solutions. These materials were utilized in the preparation of electrocatalysts toward the oxidation of carbon monoxide and glucose. In situ reflectance infrared spectroscopy measurements demonstrated that AuPt anodes were more active than Pt in the removal of adsorbed CO at ca. 0.2 V vs. RHE and for the dehydrogenation of glucose to gluconate. (C) 2012 The Electrochemical Societ

New Preparation of PdNi/C and PdAg/C Nanocatalysts for Glycerol Electrooxidation in Alkaline Medium

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Glycerol oxidation on nickel based nanocatalysts in alkaline medium - Identification of the reaction products

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