Amorphous Diamond-like Carbon Electrodes: The Catalytic Effect of Platinum Admixture

Abstract

The kinetics of electrode reactions in the Fe(CN)^3-/4- ₆ redox system is studied on the platinum-doped (Pt content up to 15 at. %) amorphous diamond-like carbon thin-film electrodes. The wide-gap diamond-like carbon is electrochemically inactive per se; yet, it acquires the electrochemical activity 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 platinum content, the electrode differential capacitance increases smoothly, and the resistivity of the material remains practically constant. The effect 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 the electrode/solution interface have a nonuniform character.