Charge Reorganization at the Adsorbate Covered Electrode Surface Probed through in Situ Resonant X-ray Diffraction Combined with ab Initio Modeling

Abstract

Understanding the charge distribution and bonding mechanism at the polarized solid-liquid interface is a fundamental challenge in electrochemistry which impacts on applications ranging from materials processing to renewable energy production. The applied potential, ions in solution and the polarization of the interface all combine to alter the bond formation and the interfacial charge distribution thus techniques must be developed to provide in-situ characterization of the interface.Here we present a combination of in-situ resonant surface x-ray diffraction studies and self-consistent DFT calculations to assess the charge distribution and bonding mechanism for the adsorption of bromide anions onto a single crystal Cu(001) electrode surface. Comparison between the experimental and modelled data gives detailed information about the charge distribution at the interface and the bonding of specific adsorbates, predicting a charge rearrangement rather than charging of the atoms involved and a surface dipole moment situated at the metal surface.

In Situ and Operando X-ray Scattering Methods in Electrochemistry and Electrocatalysis

“…This allows geting insights into changes of the electronic orbitals due to interface processes, such as electron transfer and orbital hybridization. Although the application of this DFT-assisted approach to the electrochemical interface is still in its early stages, some interesting results have recently been published by Soldo-Olivier, Grunder, and co-workers. , In this work, pioneering experimental results on the charge distribution at metal–electrolyte interfaces, specifically platinum and Br-covered copper electrodes, were reported. These studies found that, contrary to common belief, the surface charge is not located directly at the metal surface but spread out over the two outermost atomic planes.…”

“…However, with the increasing availability of fourth generation synchrotron sources and XFELs, also dynamic studies of less reversible processes may get into reach. Finally, also the electronic interface structure of halide-covered electrodes has been recently probed by pioneering studies of Grunder et al, using resonant surface X-ray diffraction. , Together with ab initio calculations, these measurements allowed to determine the charge distribution at c (2 × 2) - Br covered Cu(100) electrode. They showed that the bonding of the chemisorbed adsorbate to the metal leads to a rearrangement of the charge and a shift of the surface dipole moment into the metal electrode …”