A sketch of the setup used for the electrowetting experiments is illustrated in Figure . HOPG was freshly cleaved and placed at the bottom of a quartz container. Within a few seconds the container was filled with the surrounding aqueous electrolyte (LiCl) to minimize the adsorption of airborne impurities on the surface of the electrode. Subsequently, the DCB droplet was deposited on the basal plane of HOPG by the controlled flow of the solvent through a micropipette using a microinjector (PV820 Pneumatic PicoPump, from World Precision Instruments).