Projet ANR-06-JCJC-0111 – ECRINS : ElectroCatalyse et diffraction de Rayons x IN situ sur Surfaces bien-définies
Programme : Programme "Jeunes chercheuses et jeunes chercheurs" (JCJC) 2006
Année de financement : 2006
Coordinateur du projet : CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE RHONE-ALPES SECTEUR ALPES (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE RHONE-ALPES SECTEUR ALPES)
Partenaires : Centre national de la recherche scientifique
Montant : 145000.0 euros
Date de début : 2006
Durée : 36 mois
Résumé : The project is mastering the X-Ray Diffraction technique, when used in situ in electrolytic medium on well-defined surfaces. Thanks to the third generation of synchrotron radiation source, this method, which stands at the edge of physics and chemistry, would enable a better understanding of the physicochemical phenomena occurring at the electrode surface during its use in electrocatalysis. Either in fuel cells or in electrosynthesis, the electrode should not be considered as a steady material during operation. For example, its surface may undergo potential-induced reconstructions, and the distance between two adjacent atomic planes may vary. Also, in the case of bimetallic electrocatalysts, the use of which is growingly wide spreading, interdiffusion mechanisms may yield surface alloy formation in the first atomic layers of the electrode. Such phenomena could result in important electrocatalytic activity variations for the studied systems. This project aims at analyzing them closely, using in situ X-Ray Diffraction (XRD) coupled to electrochemistry, during operation of the electrodes. Such complex experiments require circumstantial process of operation and analysis; the samples will be electrochemically elaborated by metallic deposition on various single crystal electrodes. The so-obtained deposits will be controlled and optimized using scanning tunneling microscopy. Specific electrochemical cells will then be developed for in situ XRD measurements. Only the synchrotron high brightness X sources (ESRF  Grenoble; SOLEIL  Saclay) will provide sufficient sensitivity to detect the surface modifications during operation. First model system we will start working on is Pd underpotential deposits on Pt(111). We want to see the consequences of electrochemically inserted hydrogen on the deposit structural arrangement. Second model system is nickel underpotential deposition on Pt(110). On thus surfaces, we aim at detecting the influence of carbon monoxide adsorbtion on the atoms near to the surface. Third model system we will explore is Au deposited on Pt(111), considering one or two gold layers. This latter system undergoes multiple reconstructions, incompletely characterized, for which the volumic effects remain unknown. Finally, using deposits of Pd on Au(111), we will study the issue of surface alloy formation. The data analysis will naturally consist of an important part of our work. This project enters a wider objective: the creation of a strong research team on Fundamental Electrocatalysis in the LEPMI (Grenoble). This group should master several coupled techniques, and display international recognition. It will be able to join future European networks of excellence and other high-level world-wide collaborations. In situ X-Ray Diffraction in electrochemistry on single crystal electrodes will be one of its highlight techniques.