We find a fundamentally different behavior in the reductive direction. For maximum potentials below |-2.08 V|, a comparison of forward and backward scans suggests full electrochemical reversibility (Fig. , blue curve). Scanning to even more reductive potentials shifts the drop of the differential capacitance to higher potentials with each subsequent scan (see the shoulder forming in the red curve, which is a measurement that was performed after the film was reduced below -2.08 V several times), which is mirrored by the same behavior in the respective back scans (Fig. ). In addition, the measurement at highly reductive potentials exhibits a shoulder at approx. -2 V in the forward and backward scans. We find comparable signs for electrochemical reversibility until -2.08 V in the steady-state conductivity (Fig. ).