Electrochemical behavior of nanocrystalline diamond thin films grown in electrical arc plasma

Abstract

Nitrogenated nanocrystalline diamond films with controlled electrical conductivity are grown in electrical arc plasma in CH4/H2/Ar/N2 gas mixtures and characterized by scanning electron microscopy and spectroscopic measurements. Their electrochemical properties are studied by electrochemical impedance spectroscopy. Transfer coefficients of reactions in the [Fe(CN)6]3−/4− redox system are determined. The electrochemical behavior of the material is controlled by its nitrogenation (3–20% N2 in the reaction gas mixture). The nitrogenated nanocrystalline diamond has higher differential capacitance in indifferent electrolyte (1 M KCl) solution than not nitrogenated one; the nitrogenation also increases the reversibility of reactions in the [Fe(CN)6]3−/4− redox system. By and large, with nitrogenation of diamond, its electrochemical behavior changes from the one characteristic of a “poor conductor” to that characteristic of metallike conductor. In this respect the nanocrystalline diamond electrodes grown in the electrical arc plasma are similar to those grown in microwave plasma.