ELECTROCHEMICAL PROPERTIES OF HYDROXYPHENAZINE-COATED ELECTRODES

Glassy carbon and gold electrodes were coated with 1-hydroxyphenazine, and the electrochemical properties of these electrodes were tested using them as a rotating disc electrode to reduce Ru (bipy)33+, Fe3+, quinoxaline, O2, and to oxidize Eu2+. The fixed redox couple can be reversibly reduced and oxidized, and acts as an intermediate medium for the electron transfer. For example the Ru(bipy)33+ (E1/2= 1010 mV vs. SCE. (saturated calomel electrode) on a glassy carbon electrode in 1M H2SO4) is only reduced at 50 mV, whereas the oxidation of Eu2+ (E1/2= −460 mV vs. SCE. on a Hg-electrode in 1M HCl) takes place at − 100 mV. The heterogeneous rate constant depends on the second order reaction between the attached coating and the redox couple in solution. Depending on this rate constant, selectivity of the electrode is observed.