Experiments were performed in a glovebox under nitrogen atmosphere and additionally, the used full-glass gas tight electrochemical cell was placed in a faraday cage for better electrical shielding. A three-electrode arrangement was employed: A 3 mm diameter Pt disc electrode (Metrohm part no. 6.1204.310) as working electrode (WE), a 1 mm diameter coiled platinum wire as counter electrode (CE) and a Haber-Luggin double-reference electrode (RE) composed of a Ag/Ag + system (1 mm diameter silver wire in a 0.01 M AgClO4 solution in 0.1 M n-Bu4NPF6/CH3CN) capacitively coupled (10 nF) to a Pt wire which is immersed into the electrolyte next to the capillary opening. To avoid any contamination of the electrolyte within the sample chamber by the reference electrode solution, or vice versa, an additional frit filled with 0.1 M n-Bu4NPF6/CH3CN was inserted between the Haber-Luggin capillary and the reference electrode compartment.