Systematic study of the beam effect on hydrogen evolution reaction studied by operando electrochemical transmission electron microscopy

Oct 5, 2023 | Stages, thèses

Laboratoire: MPQ (Matériaux et Phénomènes Quantiques), Université Paris Cité & CNRS
Adresse: Bâtiment Condorcet – 10 Rue A. Domon et L. Duquet – 75013 Paris
Directeur de stage/thèse: Nathaly Ortiz Peña
Tel: 0157276983
e-mail: nathaly.ortiz@u-paris.fr

Scientific project:

Deciphering the complete lifeline of electrocatalysts is pivotal to the progress of efficient and sustainable energy conversion devices and will certainly be a step forward in their extended implementation. Whether energy is stored or produced, the half reactions involved in the overall process take place at the electrodes of an electrochemical cell. In heterogenous electrocatalysis, catalytic properties are related to the surface chemistry of the electrode material at the sub-micrometer scale. Thereby, understanding structural, compositional and morphological changes at the single-particle level would pave the way to improvement of activity, selectivity and stability.1 In addition, catalyst/electrolyte interfaces are complex and dynamic, extremely difficult to reconstruct from post-mortem analysis, where the electrolyte is not present anymore. Hence, the transformations occurring at these interfaces must be probed in situ and operando. Questions such as the long-term stability in acidic medium, the structure of the electrical double layer, the origin of multifunctionality, the limits of dispersibility (the impending question of single atom catalysts), effect of the support on the electrocatalytic activity and selectivity or any synergistic effects on the activity, become fundamental in the progress of the field and demand of an integrated effort to be solve. Thus, have been developing a multi-modal in situ/operando approach allowing to study operando the electrocatalytic activity of single Pt nano-assemblies towards water reduction by high-resolution label-free optical microscopy in combination with electrochemical transmission electron microscopy (EC-TEM). We have implemented a complementary methodology to track the precipitation of Ni(OH)2 on top of Pt nano-assemblies as consequence of the evolution of hydrogen. This work is being developed in collaboration between TERS team at ITODYS and the MEANS team at MPQ from the Université de Paris Cité in the frame of a Labex project.
This internship will focus on the systematic study of the electron beam effect in the observation in operando conditions with the EC-TEM of the water reduction over electrodeposited Pt and Pd nano-assemblies. We look to quantify the synergistic effect between the electrochemical potential and the electron beam dose during the production of H2. The student will be involved from the sample deposition by nanopipette technique electrodeposition with a highly resolved optical microscopy technique followed by in situ EC-TEM observations and data treatment. The student should be able to implement tools to track morphological evolution from in situ recordings and correlate them to the electrochemical information.

Methods and techniques: in situ electrochemical transmission electron microscopy, electrocatalysis, high resolution optical microscopy, correlative multiscale

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