MASTER DE CHIMIE DE PARIS CENTRE - M2S2 - Lise

MASTER DE CHIMIE DE PARIS CENTRE - M2S2
Proposition de stage 2015-2016
Internship Proposal 2015-2016
Spécialité(s) / Specialty(ies) :
 Chimie Analytique, Physique, et Théorique / Analytical, Physical and Theoretical Chemistry :
☐Chimie Moléculaire / Molecular Chemistry :
Matériaux / Materials:
☐ Ingénierie Chimique / Chemical Engineering:
Laboratoire d’accueil / Host Institution
Intitulés / Name : Laboratoire Interfaces et Systèmes Électrochimiques (LISE) UMR 8235 CNRS
Adresse / Address : Case 133, 4 place Jussieu 75005 Paris
Site Web / Web site : http://www.lise.upmc.fr/
Directeur / Director (legal representative) : HUET François
Tél / Tel : 01 44 27 41 48
E-mail : [email protected]
Responsables du stage / Supervisors
Nom, Prénom : SANCHEZ-SANCHEZ Carlos
KLEIN Lorena, IRCP UMR 8247 (ENSCP,
Fonction :
Chargé de Recherche CNRS (LISE)
CNRS)
Tél :
01 44 27 41 58
Ingénieur de Recherche CNRS
E-mail :
[email protected]
01 44 27 80 18
[email protected]
Nom, Prénom : VIVIER Vincent
Fonction :
Directeur de Recherche CNRS (LISE)
Tél :
01 44 27 41 58
[email protected]
E-mail :
Période de stage / Internship period: Février-Juin 2016 / February-June 2016
Gratification / Salary : 546.01 €/mois
Sujet / Title : Atomic imaging of electrocatalysts for energy production
1. Projet scientifique / Scientific Project :
Electrochemistry represents a bridge for the efficient inter-conversion of chemical and electrical energy
in the strategic field of energy. However, fuel cells, one of the most promising electrochemical
conversion device for generating electricity are still in the development stage due to the current
limitations in their electrocatalyst performance. The electrocatalytic reactions participating in those fuel
cells use catalytic electrode materials that accelerate the heterogeneous electron transfer reactions. This
is because the catalyst surface stabilizes the reactants, products or reaction intermediates by an
adsorption process, which allows a reaction pathway with a lower activation energy, since otherwise
direct formation of the reaction product would be energetically unfavourable. However, nowadays, it
remains still open a challenging question; what are the active sites on the electrocatalyst surface which
mainly control the catalytic performance in the electron transfer reactions at the atomic level? Thus,
it is a key issue to correlate the local reactivity of an electrocatalytic material to its crystallographic
structure using appropriate in situ techniques and model systems to understand in detail which
parameters play a predominant role in the performance of those catalysts. The scanning tunneling
microscopy (STM) and in particular, the electrochemical scanning tunneling microscopy (EC-STM)
represent one of the most advanced techniques for topographical imaging of electrode materials, since
they allow in situ atomic resolution imaging [1]. These techniques map the local density of atomic
states thanks to the tunneling current feedback between the tip and the sample gap, which is in the
Ångströms (10-10 m) order of magnitude.
In this project, the use of platinum single crystal electrodes Pt(hkl) as a model catalytic system [2]
should facilitate understanding the elementary steps in different electron transfer reactions and their
relationship with the catalyst surface structure. Moreover, it has been widely reported in the literature
surface modification of Pt(hkl) electrodes by addition of different foreign atoms (monolayers), which
represents an easy and convenient method to achieve highly efficient electrocatalysts [3]. These foreign
atoms are metals or semimetals that adsorb irreversibly on the Pt(hkl) electrode surface. Then, figure 1
shows a sketch of the main goal of this project, where we propose bismuth (Bi-Pt(hkl)) and sulphur (SPt(hkl)) as a surface modifier on Pt(hkl) as a model systems for EC-STM imaging.
Figure 1. STM and EC-STM imaging of a model Pt(hkl) electrode modified by Bi or S adsorbed atoms at the surface.
Main tasks in the project:
1) Atomic STM imaging of highly oriented pyrolytic graphite (HOPG) electrodes in the absence of
solution.
2) Atomic STM imaging of model Pt(hkl) electrodes modified on their surface with adsorbed nonmetallic atoms (Bi or S) in the absence of solution.
3) Fabrication of EC-STM tips by electrochemical methods.
4) EC-STM imaging of model Pt(hkl) electrodes modified on their surface with adsorbed non-metallic
atoms (Bi or S) in the presence of H 2 SO 4 or HClO 4 solution and under potentiostatic control.
This is a challenging research project involving 2 different laboratories, LISE UMR 8235 and IRCP
UMR 8247. In particular, this project would try to take advantage of all the expertise already
accumulated in both groups of research. On the one hand, the high quality skills in STM and EC-STM
imaging mainly devoted to study corrosion phenomena already present in the IRCP [4] and on the other
hand, the large background in electrochemical instrumentation for characterizing electrocatalytic
reactions already present in the LISE [5]. However, this represents an important challenge for the stage
candidate, since experimental work would be performed in both laboratories, the LISE in the UPMC
and the IRCP in the ENSCP.
2. Techniques ou méthodes utilisées / Specific techniques or methods
For imaging: Scanning tunneling microscopy (STM) and Electrochemical scanning tunneling
microscopy (EC-STM).
For electrochemical testing: cyclic voltammetry (CV), chronoamperometry (CA), rotating disk
electrode (RDE) and in-situ electrolyses.
3. Références / References
[1] C. Stuhlmann, I. Villegas, M.J. Weaver, Chem. Phys. Lett. 219 (1994) 319.
[2] F.A. Hanc-Scherer, M.A. Montiel, V. Montiel, E. Herrero, C.M. Sánchez-Sánchez, Phys. Chem. Chem. Phys. 17 (2015)
23909.
[3] C.M. Sánchez-Sánchez, J. Souza-Garcia, E. Herrero, A. Aldaz, J. Electroanal. Chem. 668 (2012) 51.
[4] T. Massoud, V. Maurice, L.H. Klein, F. Wiame, P. Marcus, Corros. Sci. 69 (2013) 245.
[5] D. Trinh, M. Keddam, X.R. Novoa, V. Vivier, Electrochim. Acta 131 (2014) 28.