Evaluation of TiN thin film electrodes for electroanalytical purposes using scanning electrochemical microscopy

Carolina Nunes Kirchner 1Christian Radehaus 2Gunther Wittstock 1

1. Carl von Ossietzky University Oldenburg, School of Mathematics and Natural Sciences, n/a, Oldenburg D-26111, Germany
2. Technische Universität, Dept. of Electrical and Information Engineering, Reichenhainer Str. 70, Chemnitz 09126, Germany

Abstract

Scanning electrochemical microscope (SECM) can be used to extract first-order rate constants from approach curves in the feedback mode. For the analysis of more complex reaction mechanisms, this first-order rate constants can be related to different rate laws. In this example the conductivity of TiN thin film of different thickness was analysed. The experiment consisted in vertical approach of an amperometric ultramicroelectrode (UME) of controlled size and overall geometry to the sample surface (TiN film) while a reversible redox couple (ferrocene methanol / ferrocenium methanol) undergoes a diffusion-controlled electron transfer (et) reaction at the UME. The sample was biased at a potential so that it re-reduces the species being produced at the UME closing the reaction cycle. The UME current depends on the kinetics at the sample. At large tip-substrate distance the feedback is controlled by diffusion and as it approaches the surface is controlled by the kinetics of reactions at the substrate interface. The normalised current-distance curves were fit to the theoretical model in order to find the standard rate constant (k0) and then conductivity.

 

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Presentation: Short communication at SMCBS'2005 Workshop, by Carolina Nunes Kirchner
See On-line Journal of SMCBS'2005 Workshop

Submitted: 2005-08-29 14:28
Revised:   2009-06-07 00:44