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International Journal of Electrochemistry
Volume 2012, Article ID 369130, 14 pages
http://dx.doi.org/10.1155/2012/369130
Research Article

Controllable Electrochemical Activities by Oxidative Treatment toward Inner-Sphere Redox Systems at N-Doped Hydrogenated Amorphous Carbon Films

1Department of Chemistry and Earth Sciences, Faculty of Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512, Japan
2Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510, Japan
3Kanagawa Academy of Science and Technology (KAST), KSP, 3-2-1, Sakado, Takatsu-ku, Kawasaki city, Kanagawa 213-0012, Japan

Received 25 April 2011; Revised 18 July 2011; Accepted 19 July 2011

Academic Editor: Giancarlo R. Salazar-Banda

Copyright © 2012 Yoriko Tanaka et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The electrochemical activity of the surface of Nitrogen-doped hydrogenated amorphous carbon thin films (a-CNH, N-doped DLC) toward the inner sphere redox species is controllable by modifying the surface termination. At the oxygen plasma treated N-doped DLC surface (O-DLC), the surface functional groups containing carbon doubly bonded to oxygen (C=O), which improves adsorption of polar molecules, were generated. By oxidative treatment, the electron-transfer rate for dopamine (DA) positively charged inner-sphere redox analyte could be improved at the N-doped DLC surface. For redox reaction of 2,4-dichlorophenol, which induces an inevitable fouling of the anode surface by forming passivating films, the DLC surfaces exhibited remarkably higher stability and reproducibility of the electrode performance. This is due to the electrochemical decomposition of the passive films without the interference of oxygen evolution by applying higher potential. The N-doped DLC film can offer benefits as the polarizable electrode surface with the higher reactivity and higher stability toward inner-sphere redox species. By making use of these controllable electrochemical reactivity at the O-DLC surface, the selective detection of DA in the mixed solution of DA and uric acid could be achieved.