Measurements were carried out starting at the open circuit potential of the bare Pt electrode of -0.2 V vs. Ag/Ag + to -2.8 V in reductive and to 2 V in oxidative direction. Scans were performed with a potential step width of 4 mV, 50 mV amplitude, 0.06 s pulse width, 0.02 s sampling width and a 0.5 s pulse period at a measurement sensitivity of 10 µA/V. DPV measurements are iR-compensated by the integrated positive feedback function of the CHI760E.