Properties of Chemically Derivatized Nickel Electrodes: The Synthesis of an Electrocatalytic Interface

Nickel electrodes yield poor charge transfer characteristics for the oxidation and reduction of the ferrocene couple, as well as for a number of other electrochemicallyinteresting reactions. In this respect, nickel is typical of a variety of inexpensive metals which are potential electrode materials, however, which are not useful due to oxidative instability. In the case of nickel with the ferrocene redox couple, this problem can be overcome by chemical modification of the nickel electrode interface. Surface silylation techniques can be used to covalently bond various moieties to an anodized nickel electrode surface, although, these surfaces appear less reactive with respect to silylation than previously reported platinum or gold surfaces. Attachment of l, 1'ferrocendiyldichlorosilane or [Fe(CN)5(NC(CH2)3)]2SiCl2 serves to stabilize the nickel interface and to electro catalyze the ferrocene redox reaction. This effect is obtained by a combination of electron mediation by the surface attached material and inhibition of surface oxidation. The latter is in part due to a physical effect creating an environment in which oxidation is not favorable.