The differential capacitance continues to drop steadily up to higher potentials, while the conductivity falls almost to zero above a potential of about 0.8 V. During the back scan, we see clear signatures of an irreversible electrochemical process, specifically the negligible conductivity (Fig. , dotted line), a sluggish decrease in the number of accumulated charge (Fig. , dotted line) and an unsymmetric differential capacitance compared to the forward scan (Fig. ).