Description du poste

The development of efficient redox catalysts which can retain activity under continuous operation is a key challenge for the development of stable water splitting schemes. However, most reactions involved in these systems, such as oxygen or hydrogen evolution, dramatically affect the local environment pH. This phenomenon becomes a major source of complexity for understanding the long-term nanocatalyst behavior and the associated deactivation mechanisms. Indeed, being activity dependent, the extent of local pH variation becomes highly heterogeneous, depending on size, shape and nanoenvironment of each nanoobject. As a result, there is a strong demand for the development of non-invasive methodologies, able to probe chemical gradients in the vicinity of individual nano objects in operando conditions. In this internship, we plan to develop a series of new tools for probing chemical gradients in the vicinity of individual electrocatalytic particles. We propose to use nanopipettes as supports for molecular optical probes, using light activated mechanisms to localize the probes in the apex of the nanopipettes (Fig.1). This supported optical approach offers several advantages over existing methodologies: (i) fast time responses, (ii) small size, which be brought within close proximity of the nanoobject surface, (iii) inertness, only minimally affecting with the catalytic system. The work is supported by several preliminary results, including controlled surface modification with attoL precision, demonstration of pipette modification in the microscale, and preliminary demonstration pH dependent emission.For more information: https://ppsm.ens-paris-saclay.fr/en/nanopipette-based-optical-sensors-tracking-chemical-gradients-vicinity-catalytic-nanoparticles

Description de l'employeur

The internship will take place in the Supramolecular and Macromolecular Photophysics and Photochemistry (PPSM) laboratory is the chemistry laboratory within ENS Paris-Saclay, co-supervised by this school and scientific research national center CNRS.

Its activity focus on the preparation and the study of molecules and materials whose properties can be switched through various stimuli such as photons, electrons, ions or biological phenomenon. This research is applied to various fields such as environment, health, information technology and heritage science.

PPSM activities are supported by a large variety of equipments and a broad range of expertise allowing to ensure several facets of chemistry: molecular / material design, synthesis, material elaboration, multi-scale analysis and study of properties.

PPSM members are recognized within the scientific community at the national and international level and contribute to the advancement of fundamental knowledge in photochemistry, fluorescence, spectroscopy, electrochemistry, nanomaterials, molecular recognition, organic synthesis and ancient materials.

Descriptif du profil recherché

We are looking for a motivated M2 student with a background in physical chemistry or nanofabrication. Knowledge of basic scientific programming and interest for the development of original instrumentation would be a plus, but are not mandatory. The candidate will be expected to evolve in an international environment, and take part in emerging national (through interaction with the PEPR LUMA network) and european collaborations (Silesian University of Tecnology in Gliwice). A small mobility during the internship is expected. The intern will receive dedicated training in several analytical and nanofabrication techniques in the interface between photochemistry and electrochemistry. Upon mutual agreement, the internship may be extended into a PhD targeting mapping of chemical gradients around catalytic nanobjects (Fig.2), for which funding has already been secured.

Langues

Francais ou anglais