During the EMAS measurement, iR-compensated by the integrated positive feedback function of the CHI760E was activated and the measurement sensitivity of the bipotentiostat was set to 0.1 mA/V. The AC coupled signal input of the lock-in amplifier was set to 10 MΩ with an input range of 10 mV. Incoming signals were processed by a 6 th order low pass filter having a time constant of 100 ms. The resolution of the monochromator was set to 3-4 nm by adjusting the input and output slit width. Potentials of the measured data were also converted to the formal potential of the external redox couple Ferrocene/Ferrocenium (Fc/Fc + ), which was measured at 0.32 V vs. Ag pseudoreference electrode within the same setup.