Venkatesan DHANASEKARAN (Ligne SIXS, SOLEIL) soutient sa thèse intitulée "Oxide-supported Au-Pd nanoparticles for CO oxidation reaction". La soutenance aura lieu dans l'amphithéâtre de SOLEIL le 29 juin à 14h.
Résumé:
We have studied the structural properties and the catalytic activity in CO oxidation reaction of 3 and 5nm Au1-xPdx (x = 0, 0.25, 0.5, 0.75, 1) nanoparticles (NPs). In particular, we investigated the effect of the preparation technique, size and composition on the structure and catalytic behavior of the NPs. The samples were synthesized by micelle nanolithography, a technique well-adapted to yield narrow size distribution of nanoparticles. A monolayer of metal-loaded micelles was obtained on SiO2/Si(001) substrates by means of spin-coating. SEM showed that the micelles were arranged in a quasi-hexagonal pattern. Oxygen or hydrogen plasma were used to remove the polymer, reduce the metal ions and enable nanoparticle formation. We made a systematic approach to study the effect of plasma on the structure, morphology and activity of the NPs by means of grazing incidence x-ray scattering and mass spectroscopy techniques. The experiments were performed at the SixS beamline, Synchrotron SOLEIL. The oxidation behavior and CO oxidation activity of the Au1-xPdx NPs were studied at 300°C and 0.5 bar in the flow reactor XCAT available at the SixS Beamline. The CO oxidation activity measurements showed that, for a given composition, the NPs prepared using the oxygen plasma present higher CO2 conversion rate than the NPs prepared using hydrogen plasma. The Pd nanoparticles prepared using O2 plasma were found to be the most active catalyst among those studied: no synergetic effects were observed for bimetallic nanoparticles for the CO oxidation reaction.
Membres du jury:
Prof. Christian RICOLLEAU - Université Paris – Diderot
Prof. Massimiliano MARANGOLO - Université Paris 6
Dr. Marie Claire SAINT-LAGER - Institut Néel - Grenoble
Dr. Beri MBENKUM - NanoArc Ltd. - Barcelone
Dr. Alina VLAD - Synchrotron SOLEIL
Prof. Yves GARREAU - Université Paris - Diderot / Synchrotron SOLEIL
Dr. Alessandro COATI - Synchrotron SOLEIL
