Preparation and characterization of Nafion (R) coated sphere-cap mercury microelectrodes

The preparation and characterisation of a series of Nafion(R) coated sphere -cap mercury microelectrodes, grown onto a platinum-microdisk, were illustr ated. The mercury microelectrodes were prepared by ex-situ electrodepositio n of mercury onto the platinum substrate microdisk: thereafter they were mo dified by dip-coating the electrodes in Nafion(R) solutions over the concen tration range 2.5-0.03% w/v. The performance of these modified electrodes w as tested in Ru(NH3)(6)Cl-3 solutions. It was found that the voltammetric b ehaviour of the modified electrodes depended on both solution composition o f Nafion(R) and size of the mercury deposit employed for their preparation. Because of the sphere-cap geometry of the substrate electrode, in general, inhomogeneous Nafion(R) films were obtained. It was also shown that from d ilute Nafion(R) solutions ( < 0.31%w/v) it was possible to prepare very thi n films of Nafion(R), which were loaded with the probe cation in relatively short times, even in quiescent solutions. (C) 1999 Elsevier Science S.A. A ll rights reserved.