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

Understanding the charge distribution and bonding mechanism at the polarized solid-liquid interface is a fundamental challenge in electrochemistry which impacts 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. A comparison between the experimental and modeled 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.