In-situ surface x-ray diffraction has enabled an atomic/molecular-level understanding of the electrochemical interface, including its potential and time dependence, to be developed. [1] Specifically, for electrodeposition the influence of additives and adsorbates onto growth and nucleation behaviour could be established. Halogens on metal surfaces are prototypic adsorbate systems but the adsorption of halide ions especially on copper is also of major importance for on-chip metallization in ULSI microchip production. Halide ions on Cu surfaces form an inhibiting adsorbate layer with polyethylene glycol (PEG). Even though the influence of the additives combination on the shape evolution of the Cu deposit was subject of numerous studies, their precise role during the elementary steps of the deposition with regards to altering the charge distribution and dipole moment at the interface is largely not understood. [1] While information about the atomic structure of the electrode surface in electrochemical in-situ cells has been widely investigated, insight into the charge distribution and the structure of the electrolyte at the interface is still lacking. Combining x-ray spectroscopy and x-ray diffraction to gain site-specific information about the charge distribution at buried interfaces is a promising tool. [2,3,4]

Studies on the metal-halide interface and how the use of surface x-ray scattering techniques can help to characterise electrochemical interfaces in-situ in order to link, structure and stability and morphology changes will be presented. [1, 4] Advances in these directions offer possibilities in elucidating atomic scale models of the electrochemical interface and thus will help to establish structure-stability-reactivity relationships which will help to understand growth kinetics and nucleation behaviour.

References:

[1] In-Situ Surface X-ray Diffraction Studies of Copper Electrodes: Atomic-Scale Interface Structure and Growth Behavior. Gruender, Y., Stettner, J., & Magnussen, O. M. (2018). Journal of the Electrochemical Society; 166(1), D3049-D3057. doi:10.1149/2.0071901jes

[2] Probing the charge distribution at the electrochemical interface; Y. Gründer and C. A. Lucas, Physical Chemistry Chemical Physics, 2017, 19, 8416

[3] Simulation of Surface Resonant X-ray Diffraction; Y. Joly et al., J. Chem. Theory Comput,. 2018, 14, 973−980

[4] Charge Reorganization at the Adsorbate Covered Electrode Surface Probed through in Situ Resonant X-ray Diffraction Combined with ab Initio Modeling;Y. Grunder, C. A. Lucas, P. B. J. Thompson, Y. Joly, Y. Soldo-OlivierJ. Phys. Chem. C 2022, 126, 9, 4612–4619