title: Structure and electrochemical properties of carbon films prepared by a electron cyclotron resonance sputtering method.
abstract: 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 A). 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, 10(19)-10(20) 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 microM bisphenol A, which usually fouls the electrode surface with oxidation products.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Jia
authors.forename: Dai
authors.initials: D
authors.lastname: Kato
authors.forename: Ryoji
authors.initials: R
authors.lastname: Kurita
authors.forename: Yukari
authors.initials: Y
authors.lastname: Sato
authors.forename: Kenichi
authors.initials: K
authors.lastname: Maruyama
authors.forename: Koji
authors.initials: K
authors.lastname: Suzuki
authors.forename: Shigeru
authors.initials: S
authors.lastname: Hirono
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ando
authors.forename: Osamu
authors.initials: O
authors.lastname: Niwa
mesh_terms: D001895:Boron / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D017357:Cyclotrons / Q000295:instrumentation*; D018130:Diamond / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D004579:Electron Transport; D005292:Ferricyanides / Q000737:chemistry; D007700:Kinetics; D017975:Ruthenium Compounds / Q000737:chemistry; D012680:Sensitivity and Specificity; D013499:Surface Properties
chemical_list: D005292:Ferricyanides; D017975:Ruthenium Compounds; C007931:hexacyanoferrate III; C031584:hexammineruthenium; D002244:Carbon; D018130:Diamond; D001895:Boron