The experiments were performed in a large cylindrical glass cell containing 0.01 M KOH. The two electrodes for aCGDE (PWE and plasma counter electrode -PCE) and the three electrochemical electrodes (auxiliary electrode -AE, reversible hydrogen electrode -RHE, and electrochemical counter electrode -ECE) are immersed in the cell as shown in the schematic illustration in Fig. . A glass tube is placed around the plasma counter electrode to remove volatile products created at the PCE. In our studies, the AE was placed at a distance of either 1.5 cm or 4.5 cm from the PWE. The applied voltage between the PWE and the PCE is given in V, while the potential at the AE is given on the RHE scale (V RHE ). A detailed description of the experimental set-up, materials used and experimental procedures is provided in the experimental section. The effect of aCGDE on the AE was studied by comparing the variation of electrode potential (E) vs. time (t) (Fig. top row) with the current density (j) vs. t (Fig. middle and bottom row). Each experiment consists of a combination of the following experimental steps: