The kinetic behavior of the modified electrode was then studied using rotating disk electrode (RDE) voltammetry. In the case of NiCl2(bpy), a diminished current response in consecutive cycles at an unmodified glassy carbon RDE is observed. When the same measurements were performed with the silver-nanoparticle modified RDE, the peak current response of the Ni(II)/Ni(0) redox couple was slightly lower and its current also decreased with continuous cycling, but at a notably slower rate (Figure ). The initial current response could be restored to the glassy carbon electrode by a potential excursion to +1.5 V vs. Ag/AgCl, indicating that passivation is likely occurring through over-reduction and deposition of the catalyst on the electrode surface. Supporting this hypothesis, the cell potential (at constant current) of the reaction revealed a significant difference between the reactions with and without AgNO3. The potential of the reaction in the presence of AgNO3 (Ecell = -1.15 V vs. Ag/AgCl) was 510 mV more positive than the reaction without silver (Ecell = -1.66 V vs. Ag/AgCl). This shift in potential (effectively a lower overpotential) could prevent the over-reduction of the catalyst which we believe to be responsible for the passivation of the electrode. To test this hypothesis (Figure -II), the cross-coupling reaction was run at a constant potential of -1.15 V vs. Ag/AgCl without a silver salt. These conditions resulted in a 10% increase in the yield of 39. Furthermore, a reaction conducted with intermittent potential excursions to +1.5 V (70 s at +1.5 V vs. Ag/AgCl for every 11.5 mins of -6 mA), resulted in an 11% increase in the yield of 39, consistent with the results of the RDE experiments and further providing evidence for catalyst over-reduction, and electrode passivation at more forcing potentials-a deleterious process partially obviated by the silver layer.