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Reinvestigation of a ferric ion‐selective electrode based on the chalcogenide glass Fe x Se 60 Ge 28 Sb 12 ( x = 1–10)
Author(s) -
Koenig Christian E.,
Graber Erich W.
Publication year - 1995
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140071117
Subject(s) - chalcogenide , electrode , electrolyte , ion , materials science , chalcogenide glass , electrode potential , analytical chemistry (journal) , layer (electronics) , surface layer , x ray photoelectron spectroscopy , inorganic chemistry , chemistry , chemical engineering , optoelectronics , composite material , chromatography , organic chemistry , engineering
A ferric ion‐selective electrode based on the iron containing chalcogenide glass Fe x Se 60 Ge 28 Sb 12 ( X = 1–10) was reinvestigated in order to optimize the electrode characteristics and to elucidate the mechanism of the potential determining process. By modifying the preparation procedure of the chalcogenide glass described in the literature and of the electrode configuration highly stable sensors were obtained. These sensors show super‐Nernstian slopes of the calibration plots of about 65 mV/decade, selectivity coefficients of about 10 −4 for several heavy metal ions and a potential drift of 3–4 m V/h due to some slow corrosion process occuring at the electrode surface. Furthermore the data of impedance, cyclovoltammetric, and XPS experiments show that the conditioning process of the electrode leads to a modified surface layer which behaves like a specific ion exchanger for Fe 3+ ions. In contact with a Fe 3+ containing electrolyte, the exchange of Fe 3+ ions between the electrolyte and the modified surface layer leads to the injection of holes from the surface layer into the bulk of the chalcogenide glass. Thus the fermi level of the material is shifted, causing the observed potential change.