Electrochemical investigations of surface functional groups on isotropic pyrolytic carbon

✍ Scribed by Barry D Epstein; Erminia Dalle-Molle; James S Mattson

• Book ID: 102991231
• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 625 KB
• Volume: 9
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(71)90082-0

✦ Synopsis

Isotropic pyrolytic carbon (Pyrolite@) electrodes subjected to electrochemical oxidation at widely varying current densities develop a very distinctive, reproducible surface functionality. This surface functional group exhibits a peak reduction current in the region from 0 to-400 mV (vs. SCE) in 1 M HzS04, and is easily quantitatively reduced. It can then be reoxidized, with a peak oxidation current occurring in the range from + 1300 to + 1700 mV (vs. SCE) in 1M HzS04, to re-form the original surface group. The cycle can then be repeated ad infinitum, with quantitative reduction and oxidation every time. The oxidized and reduced forms of the surface functionality may correspond to quinone and hydroquinone groups. In view of the high dipole moment associated with quinone oxygen attached to large ring systems, a high electron density would be expected at the oxidized carbon surface. The specific adsorption of p-nitrophenol on carbon, thought to be an electron donor-acceptor complex, is shown to be strongly dependent on the state of surface oxidation. Coulometric studies indicate that the p-nitrophenol ad-