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X‐ray photoelectron spectroscopic studies of carbon‐fiber surfaces. 19. Surface chemical changes during electrochemical oxidation in base
Author(s) -
Weitzsacker Cara L.,
Sherwood Peter M. A.
Publication year - 1995
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740230715
Subject(s) - polyacrylonitrile , x ray photoelectron spectroscopy , electrochemistry , electrolyte , valence (chemistry) , chemistry , inorganic chemistry , carbonate , ion , oxidizing agent , carbon fibers , carboxylate , materials science , electrode , chemical engineering , organic chemistry , polymer , composite material , composite number , engineering
Electrochemical oxidation of polyacrylonitrile‐based carbon fibers in a basic electrolyte was studied and the surface chemical changes monitored by core and valence‐band x‐ray photoelectron studies. These studies show that potentionstatic treatment under strongly oxidizing conditions in a sodium hydroxide electrolyte for 20 min leads to a surface consisting of a substantial amount of weakly attached carbonate ions with a lesser contribution from carbosylae and other C/O groups attached to the carbon‐fibre surface. The valence‐band spectrum for a carboxylated carbon fibre calculated by a multiple‐scattered wave Xα calculation on a CO 2 − −Substituted coronene (C 36 O 24 12− ) shows that a carboxylate‐functionalized carbon fiber would make only a partial contribution to the observed spectrum, which shows considerable similarities with the spectrum of the carbonate ion. The weakly attached carbonate ions were reduced in surface concentration by repeated washing.