For the X-ray photoelectron spectroscopy (XPS) measurements, a SPECS PHOIBOS 150 spectrometer implemented at the DAISY-FUN cluster tool was used. It is equipped with an Al Kα Xray source (monochromatic Focus 500 with XR50 M (SPECS), hv = 1486.74 eV). Survey and detail spectra were measured in fixed analyser transmission mode, while choosing a pass energy of 20 eV (step size of 0.5 eV) for the survey and 10 eV (step size of 0.05 eV) for the core levels. The system was calibrated to 0.00 eV binding energy of the Fermi level of sputtercleaned Au and Cu as well as to the emission lines of Au 4f7/2 at 83.98 eV, Ag 3d5/2 at 368.26 eV, and Cu 2p3/2 at 932.67 eV binding energy with deviations ≤0.1 eV. The valence band spectra were measured with ultraviolet photoelectron spectroscopy (UPS), using a helium lamp (HIS 13 Mono, Focus GmbH) with monochromatized HeII radiation of hv = 40.81 eV. Here, a pass energy of 5 eV and a step size of 0.05 eV was chosen. The data analysis was performed with CasaXPS, version 2.3.22. The O 1s core level spectra were fitted with a Shirley background and peaks of a GL(30) line shape. Intensity calculations were done based on relative sensitivity factors published by Scofield. Raman Spectroscopy Spectra were acquired with a Bruker Senterra I Raman microscope with a 532 nm laser. Ex-situ measurements were performed at 9-18 cm -1 resolution, 50x objective, a laser power of 37 mW on the sample surface, and 5 s integration time with 2 coadditions. For in-situ measurements, a commercial cell named "TSC Raman" from rhd instruments was used. It was operated in a three-electrode configuration. As counter electrode, a goldplated ring was installed in the base and as reference electrode a leak-free micro Ag/AgCl electrode from Innovative Instruments was used and calibrated against a reversible hydrogen electrode (RHE, HydroFlex, Gaskatel). Potential control was performed with a potentiostat from Gamry instruments (Interface 1000E). The potential was increased in steps of 0.05 V from 1.20-1.50 V, followed by steps of 0.02 V from 1.50-1.70 V vs RHE. At each step, the potential was applied for 110 s while the Raman spectrum was taken after 60 s of applied potential. Here, the 20x objective was chosen, with a laser power of 36 mW reaching the sample surface, and again 5 s integration time with 2 coadditions was set. For plotting and interpretation of the in-situ Raman spectra, a linear background was subtracted in the regions of interest.