title: A Study on Electrolytic Corrosion of Boron-Doped Diamond Electrodes when Decomposing Organic Compounds.
abstract: Electrolytic corrosion of boron-doped diamond (BDD) electrodes after applying a high positive potential to decompose organic compounds in aqueous solution was studied. Scanning electron microscopy images, Raman spectra, and glow discharge optical emission spectroscopy revealed that relatively highly boron-doped domains were primarily corroded and relatively low boron-doped domains remained after electrolysis. The corrosion due to electrolysis was observed especially in aqueous solutions of acetic acid or propionic acid, while it was not observed in other organic compounds such as formic acid, glucose, and methanol. Electron spin resonance measurements after electrolysis in the acetic acid solution revealed the generation of methyl radicals on the BDD electrodes. Here, the possible mechanisms for the corrosion are discussed. Dangling bonds may be formed due to abstraction of OH groups from C-OH functional groups by methyl radicals generated on the surface of the BDD electrodes. As a result, the sp3diamond structure would be converted to the sp2carbon structure, which can be easily etched. Furthermore, to prevent electrolytic corrosion during electrolysis, both the current density and the pH condition in the aqueous solution were optimized. At low current densities or high pH, the BDD electrodes were stable without electrolytic corrosion even in the acetic acid aqueous solution.
authors.affiliation: Department of Chemistry, Keio University , 3-14-1 Hiyoshi, Yokohama 223-8522, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kashiwada
authors.affiliation: Department of Chemistry, Keio University , 3-14-1 Hiyoshi, Yokohama 223-8522, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ootani
authors.affiliation: International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Tateyama
authors.affiliation: Department of Chemistry, Keio University , 3-14-1 Hiyoshi, Yokohama 223-8522, Japan.|JST-ACCEL, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Einaga
keywords: boron-doped diamond electrodes; electrolytic corrosion; methyl radicals; organic compounds; wastewater treatment