Amorphous diamond-like carbon electrodes: The catalytic effect of platinumadmixture

The kinetics of electrode reactions in the Fe(CN)(6)(3-/4-) redox system is studied on the platinum-doped (Pt content up to 15 at. %) amorphous diamon d-like carbon thin-film electrodes. The wide-gap diamondlike carbon is elec trochemically inactive per se; yet, it acquires the electrochemical activit y on adding platinum to the film bulk during the film growth. The effect of platinum is of a threshold character; at the same time, with increasing pl atinum content, the electrode differential capacitance increases smoothly, and the resistivity of the material remains practically constant. The effec t is explained with a model which assumes that both the conductance in the film bulk and the catalytic action of platinum on the charge transfer at th e electrode/solution interface have a nonuniform character.