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In situ Surface Resonant X-Ray Diffraction to probe the electronic structure at electrochemical interfaces

  • Yvonne Soldo-Olivier (CNRS & Université Grenoble Alpes, France)
Date
Monday 30 March 2020
Time
Address
Hotel NH Noordwijk Conference Centre Leeuwenhorst

Y. Soldo-Olivier1, E. Sibert2, M. De Santis1 and Y. Joly1
1 Institut Néel (CNRS & Université Grenoble Alpes), 25 Rue des Martyrs, Grenoble, France
2 LEPMI, St. Martin d’Hères, France.

Email: yvonne.soldo@neel.cnrs.fr

Electro-catalysts allow speeding up electrochemical reactions typically occurring at the electrochemical interface, singular domain of some Ångstrom of thickness where the charge exchange between the conducting electrode and the electrolyte occurs. Such materials have important applications in several domains, like energy storage, chemical synthesis, bio-sensors...

In this context, the description of the electrochemical interface and the comprehension of the related electro-catalytic mechanisms are of primary importance. It is first and foremost a question of material of electrode and more specifically a problem of structural and electronic properties of its surface. However, there is currently no experimental method to specifically probe the electronic structure of the surface directly under electrochemical operation and experimental evidence for the theoretical predictions regarding charge distribution is still lacking.

In this frame, we aim at developing the surface resonant x-ray diffraction (SRXRD) into a standard technique to probe charge distribution and electronic densities for electrochemical systems in in situ conditions. This can be achieved combining experimental and theoretical approaches, i.e. coupling in situ surface resonant x-ray diffraction experiments with the home-developed first principle simulation software FDMNES [1]. This approach will be able to give access to both the electronic and structural description of the atoms at the interface.

SRXRD couples surface X-Ray diffraction, widely used to solve the atomic structure at the surface of single crystals, to X-Ray absorption near edge spectroscopy (XANES), highly sensitive to the oxidation states. Ab initio FDMNES calculations, recently implemented with the simulation of surface diffraction experiments, have been further developed for electrochemical interfaces description.

We present here an in situ SRXRD study coupled to FDMNES calculations of Pt(111) in 0.1M H2SO4, a particularly interesting electrochemical model interface for the investigation of competitive anions adsorption processes hindering the kinetics of the electrocatalytic processes. Although this system has been extensively studied, the description of adsorbed sulfates in acidic media as a function of the applied potential and of the related charge exchange is still controversial.

References

  1. Y. Joly et al., Journal of Chemical Theory and Computation 14( 2), 461 (2018).

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