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International audience; Electrochemical energy converters based on biomass-based organic molecules such as glucose have recently demonstrated great potential for the development of functional bioimplantable devices such as pacemakers, but such converters lack efficient metal-based anode nanocatalysts, which could combine the stability of parameters with high performance. Here, we elaborate a technique of femtosecond laser ablation in water to synthesize bare (ligand-free) PdAu alloy nanoparticles with constituents having a variable ratio and explore these nanoparticles as electrocatalysts for glucose oxidation. Our data evidence that the combination of two metals in one bare nanoformulation can result in a strong synergetic effect, which makes the combination of high catalytic activity toward glucose oxidation with ultrafast kinetics at low potentials possible due to the presence of Au and Pd, respectively, while a bare uncontaminated surface ensures outstanding catalytic performance. We show that at an optimal ratio of constituents (50%/ 50%), PdAu nanoparticles can provide a mass activity of 60 A g −1 and an onset potential lower than 0.27 V vs. RHE, which outperform all currently existing nanoparticle-based electrodes. Our results show that bare nanomaterials prepared by laser-ablation synthesis can offer much improved characteristics as electrocatalysts for energy conversion and storage applications, while the versatility of laser synthesis can be extended to other alloy architectures in order to provide optimal characteristics for a concrete catalytic process.

We report a drastic enhancement of electrocatalytic activity toward glucose oxidation by using novel electrocatalysts on the basis of “bare” unprotected Au nanoparticles synthesized by methods of laser ablation in pure deionized water. The recorded current density of 2.65 A cm–2 mg–1 for glucose electrooxidation was higher than a relevant value for conventional chemically synthesized Au nanoparticles by an order of magnitude and outperformed all data reported in the literature for metal and metal alloy-based electrocatalysts. The enhanced electrocatalytic characteristics of laser-synthesized nanoparticles are explained by the absence of any organic contaminants or protective ligands on their surface, the relatively small size of nanoparticles, and their particular crystallographic structure. The employment of bare nanomaterials in glucose electrooxidation schemes promises a radical improvement in current biofuel cell technology and its successful application in bioimplantable devices.

International audience; We report a size-controllable synthesis of stable aqueous solutions of ultrapure low-size-dispersed Au nanoparticles by methods of femtosecond laser fragmentation from preliminary formed colloids. Such approach makes possible the tuning of mean nanoparticle size between a few nm and several tens of nm under the size dispersion lower than 70% by varying the fluence of pumping radiation during the fragmentation procedure. The efficient size control is explained by 3D geometry of laser fragmentation by femtosecond laser-induced white light super-continuum and plasma-related phenomena. Despite the absence of any protective ligands, the nanoparticle solutions demonstrate exceptional stability due to electric repulsion effect associated with strong negative charging of formed nanoparticles. Stable aqueous solutions of bare gold nanoparticles present a unique object with a variety of potential applications in catalysis, surface-enhanced Raman spectroscopy, photovoltaics, biosensing and biomedicine.

5th European-Materials-Research-Society Symposium on Laser Material Interactions for Micro- and Nano- Applications, Strasbourg, FRANCE, MAY 27-31, 2013; International audience; The experimental conditions were investigated enabling one to fabricate Au nanowire networks by pulsed laser ablation in water. The study revealed that it is possible to produce alternatively nanoparticles (or aggregates) or nanowire networks at certain wavelengths depending on the laser fluence. An Au disc immersed in double-distilled water was used as a target. The second (lambda(SHG) = 532 nm) and the third lambda(THG) = 355 nm) harmonics of a Nd:YAG laser system were utilized to produce different Au colloids. The values of the laser fluence for both wavelengths under the experimental conditions chosen were varied from several J/cm(2) to tens of J/cm(2). The optical extinction spectra of the colloids in the UV/vis region were obtained to evaluate the structure of the dispersed Au phase. Transmission electron microscopy (TEM) was applied to visualize the size and morphology of the colloidal particles. Their structure and phase composition were studied by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) and used to make an assumption on how they had been formed. (C) 2014 Elsevier B.V. All rights reserved.