Boron doped diamond (BDD) thin film electrodes have become extremely popular in recent years. Their low and stable background current, wide working potential window, microstructural and morphological stability, relatively rapid electrode kinetics etc. are key attributes that make them attractive for many electrochemical applications. A limitation of this electrode material is the high temperature (700 – 800 oC) required for deposition. This limits the types of substrates that can be coated. Another less-studied carbon electrode material is nitrogen-incorporated tetrahedral amorphous carbon (ta-C:N). ta-C:N thin-film electrodes have properties similar those of BDD electrodes and they can be deposited at room temperature. ta-C:N is a diamond-like carbon composed of a mixture of sp2 (graphite-like) and sp3-bonded (diamond) carbon along with nitrogen incorporated added during the growth. The optical properties, hardness and electronic structure can be tailored from those of graphite to those of diamond by controlling the ratio of sp2 and sp3-bonded carbon bonding. The electronic properties can also be altered by the nitrogen impurity incorporation, with a trend of increasing conductivity with increasing nitrogen content. The aim of this work is to provide an improved understanding of the structure-property relationship of ta-C:N thin-film electrodes. Specifically, we are investigating the interfacial capacitance and heterogeneous electron transfer kinetics of redox test probes at ta-C:N electrodes with various nitrogen content in room temperature ionic liquids (RTILs). RTILs are salts composed purely of ions. They present a very interesting medium in which to study electrochemical reactions. They are attracting scientific attention due to their exceptional properties, such as high thermal stability, low vapor pressure, non-flammability and high breakdown potential. Importantly, in contrast with the aqueous electrolytes, RTILs contain no solvent, which leads to a distinctly different interfacial structure and dielectric medium around the redox probe. In this presentation, we will report on the structural characterization of ta-C:N thin-film electrodes with different nitrogen content using SEM, AFM, Raman spectroscopy and XPS. Cyclic voltammetric results will also be reported for 1 × 10-3 mol L-1 ferrocene carboxylic acid, ferrocene and ferrocene methanol in the structurally-distinct RTILs. Heterogeneous electron-transfer rate constants will be reported.

Electroanalytical performance of nitrogen-incorporated tetrahedral amorphous carbon thin-films in room temperature ionic liquids

256th National Meeting (2018)

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