Amperometric sensing of catechol using a glassy carbon electrode modified with ferrocene covalently immobilized on graphene oxide

The authors report on a nonenzymatic catechol sensor that is based on the immobilization of ferrocene (Fc) on graphene oxide (GO). A glassy carbon electrode (GCE) was modified with GO which then was silanized with (3-aminopropyl) trimethoxysilane. Ferrocenecarboxaldehyde was then immobilized on GO via formation of a Schiff base. The immobilization process was monitored stepwise by using FTIR spectroscopy, X-ray diffraction, cyclic voltammetry (CV) and electrochemical impedance spectroscopy. Investigation of the modified electrode by CV revealed a pair of well- defined redox peaks with anodic and cathodic peak potentials at +0.380 and +0.277 V, corresponding to the Fc/Fc(+) redox couple. The Fc modified electrode exhibits excellent electrocatalytic activity towards the oxidation of catechol at a typical working voltage of +0.45 V (vs. Ag/AgCl). The response is linear in the 3 to 112 mu M catechol concentration range, the detection limit is 1.1 mu M, and the sensitivity is 1184.3 mu A.mM(-1).cm(-2). The sensor is stable, reproducible and reasonably selective. It was successfully applied to the determination of catechol in spiked tap water and lake water samples.