CATALYTIC ELECTROOXIDATION OF HYDRAZINE AT THE NICKEL FERRICYANIDE MODIFIED ELECTRODE - CAN AN ARRAY OF SURFACE BOUND ONE-ELECTRON REDOX CENTERS ACT IN CONCERT

The [NiFe(CN)6]2-/- derivatized nickel electrode represents an electrocatalytic surface for the mediated oxidation of hydrazine. The four-electron oxidation of hydrazine is employed as a probe of multiple electron charge transfer processes at the Ni[Fe(CN)6]2-/- interface since the observed product distribution is sensitive to the detailed mechanism and stoichiometry of electron transfer giving rise to production of NH3 if only one-electron transfer processes occur, while yielding N2H2 or N2 if multi-electron processes are present. A correlation between surface overlayer structure and charge transfer pathway is observed. A rather facile, pseudo-first order heterogeneous charge transfer rate (approximately 3 x 10(-2) cm s-1) was found for N2 production. The kinetics of the processes involved in this electrocatalysis were analyzed according to the Saveant-Andrieux theory. The electrocatalytic behavior of this system can be varied from R type behavior to R + S or (SR) and then to S + E behavior by varying the amount of the surface attached catalyst.