Structure and Electrochemical Properties of Carbon Films Prepared by a Electron Cyclotron Resonance Sputtering Method

• Published in: Analytical chemistry (Washington) Vol. 79; no. 1; pp. 98 - 105
• Main Authors: Jia, Jianbo, Kato, Dai, Kurita, Ryoji, Sato, Yukari, Maruyama, Kenichi, Suzuki, Koji, Hirono, Shigeru, Ando, Toshihiro, Niwa, Osamu
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.01.2007
• Subjects: Analytical chemistry; Biochemistry; Boron - chemistry; Carbon; Carbon - chemistry; Chemistry; Cyclotrons - instrumentation; Diamond - chemistry; Electrochemical methods; Electrochemistry; Electrodes; Electron Spin Resonance Spectroscopy - instrumentation; Electron Spin Resonance Spectroscopy - methods; Electron Transport; Electrons; Exact sciences and technology; Ferricyanides - chemistry; Kinetics; Oxidation; Ruthenium Compounds - chemistry; Sensitivity and Specificity; Surface Properties; Oxidation reduction; Dopamine; Stability; Electron cyclotron resonance; Electron transfer; Diamond; Carbon; Sputtering; Thin film; Cyclic voltammetry; Azides; Bisphenol A; Histamine; Boron; Electrochemical properties; Low current; Continuous measurement; Oxidation; Pretreatment; Room temperature
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac0610558

This paper describes the characterization, electrochemical properties, and applications of carbon films prepared by the electron cyclotron resonance (ECR) sputtering method. The ECR-sputtered carbon film was deposited within several minutes at room temperature. The optimized sputtering conditions significantly change the film structure, which includes many more sp3 bonds (sp3 /sp2 = 0.702) than previously reported film (sp3 /sp2 = 0.274)1 with an extremely flat surface (0.7 Å). The ECR-sputtered carbon films exhibit excellent electrochemical properties. For example, they have nearly the same potential window in the positive direction as that of high-quality, boron-doped diamond (moderately doped, 1019−1020 boron atoms/cm3)2 and an even wider potential window in the negative direction with a low background current, high stability, and suppression of fouling by electroactive species without pretreatment. The electron-transfer rates at ECR-sputtered carbon films are similar to those of glassy carbon (GC) for Ru(NH3)6 2+/3+ and Fe(CN)6 3-/4-, whereas they are much slower than those of GC for Fe2+/3+, dopamine oxidation, and O2 reduction due to weak interactions between electroactive species and the ECR-sputtered carbon film surface. Such a response can be attributed to the ultraflat surface and low surface O/C ratios of ECR-sputtered carbon films. ECR-sputtered carbon film is advantageous for measuring biochemicals with high oxidation potentials because of its wide potential window and high stability. Highly reproducible and well-defined cyclic voltammograms were obtained for histamine and azide ions with a peak potential at 1.25 and 1.12 V vs Ag/AgCl, respectively. The film is very stable for continuous voltammetry measurements in 10 μM bisphenol A, which usually fouls the electrode surface with oxidation products.