Since the NiOOH phase is slowly decomposing to Ni(OH)2 during the measurement in air, Raman spectra were also acquired insitu. Figure shows that with increasing potential, the peaks shift to higher wavenumbers and the peak ratio changes, irrespective of the electrolyte. The peak ratio change with elevating polarization was already observed in previous publications. In the upper row of Figure , the peak ratio is compared for insitu measurements in the various electrolytes. Dashed lines with the peak maxima in LiOH as reference are included to visualize the lower intensity at 555 cm -1 in CsOH compared to the other electrolytes, which fits to the trend seen in the ex-situ Raman measurements (Figure ). The lower row in Figure shows the spectral region of NiOO -. Garcia et al. observed a cation dependence of this region. As its intensity increases the most in CsOH electrolyte in their study, they correlate this to the increased OER activity in CsOH. In our spectra, the intensity in this region increases the most during potential increase in CsOH. Comparing the total area of the spectra obtained in different electrolytes at 1.7 V vs. RHE, there is a slight increase from LiOH to NaOH, KOH, and finally CsOH. However, this trend is not reproduced for the measurements at lower potentials or ex-situ. Possibly, the stabilization of NiOO -by the cations is stronger on the surface than in the bulk. In this case, surface enhanced Raman spectroscopy (SERS), which was not employed here, might yield more precise results. Yet another observation in the Raman spectra was that the peaks shifted to lower wavenumbers from LiOH to CsOH (Figure ). This was also observed by Garcia et al. , Michael et al. and Hou et al. and is related to a longer Ni-O bond with decreasing wavenumbers. To sum up the findings, NiOOH undergoes structural changes when activated with different alkali metal cations. With this knowledge, we want to come back to the O 1s spectrum and discuss the assignment of the peak at 528.9 eV. Payne et al. show in their O 1s spectra a smaller O 2-peak in β-NiOOH than in γ-NiOOH. This enhanced deprotonation of NiOOH in the γ-phase is consistent with the higher oxidation state of Ni found in this phase. Combined with our results from Raman spectroscopy, we can confidently argue that the change in peak ratio in our O 1s spectrum in Figure is due to a structural change of a more β-like NiOOH to a more γ-like NiOOH, when changing the electrolyte from LiOH, to NaOH, KOH, and finally CsOH.