Influence of electrochemical pre-treatment on highly reactive carbon nitride thin films deposited on stainless steel for electrochemical applications

摘要

In this work, a-CNx films prepared by DC magnetron sputtering on stainless steel substrate have been investigated as electrode materials. While their wide potential window was confirmed as a property shared by boron doped diamond (BDD) electrodes, their electrochemical activity with respect to fast and reversible redox systems, [Ru(NH_3)_6]~(3+/2+), [Fe(CN)_6]~(3-/4-) and [IrCl_6]~(2-/3-), was assessed by Electrochemical Impedance Spectroscopy (EIS) after cathodic or anodic electrochemical pre-treatments or for as grown samples. It was shown for the three systems that electrochemical reactivity of the a-CNx films was improved after the cathodic pre-treatment and degraded after the anodic one, the apparent heterogeneous rate constant k_(0app) being decreased by at least one order of magnitude for the latter case. A high k_(0app) value of 0.11 cm s~(-1) for [IrCl_6]~(2-/3-) was obtained, close to the highest values found for BDD electrodes.