Metal substrate effects on pH response of tetracyanoquinodimenthane modified electrodes
In recent work the voltammetric and spectral response of tetracyanoquinodimethane (TCNQ) modified electrodes have been described. The effect of pH of the cyclic voltammetry of these modified electrodes can be understood on the basis of the classical 3 x 3 nine-membered square scheme characteristic of quinone-hydroquinone couples. As for other compounds with quinoid structures, TCNQ exhibits quasi-reversible behavior in protic solvents with an apparent direct 2e/sup -/, 2H/sup +/ exchange in acidic pH region. This scheme is complicated further by dimer formation, disproportionation of the anion radical in strongly acidic solutions, and the apparent reduction of neutral TCNQ by hydroxide ions in very basic media (pH > 12). In basic solution the formation of TCNQ/sup -/ is clearly signaled by its electron spin resonance and visible absorption spectra. While quinone-hydroquinone couples do exhibit subtle electrochemical behavior, they are the basis for a widely used and reliable redox pH electrode. Thus an attempt to utilize TCNQ modified electrodes as a pH sensor seemed to be a logical step based on the kinship between TCNQ and benzoquinone. However, the results support the idea that the electrode substrate plays an important role in determining the response to the pH of the bulk solution. 20 references, 1 figure.
- Research Organization:
- Lorand Eotvos Univ., Budapest, Hungary
- OSTI ID:
- 6459456
- Journal Information:
- Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 56:2; ISSN ANCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400102* -- Chemical & Spectral Procedures
AROMATICS
CYANIDES
DATA
DEPOSITION
ELECTRODES
ELECTRON SPIN RESONANCE
EXPERIMENTAL DATA
INFORMATION
INFRARED SPECTRA
MAGNETIC RESONANCE
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PH VALUE
QUINONES
RESONANCE
SPECTRA
SURFACE COATING
VISIBLE SPECTRA
VOLTAMETRY