Covalent modification of glassy carbon electrode by Nile blue: Preparation, electrochemistry and electrocatalysis

In this paper a modification strategy for functionalization of glassy carbon electrode (GCE) with Nile blue (NB) is described. In this strategy the GC electrode was functionalized with 4-nitrophenyl (NP) group by electrochemical reduction of 4-nitrobenzenediazonium salt in nonaqueous media. Then the nitro group was reduced electrochemically to amine functionality. Next modification step was dialdehyde derivatization, in which glutaraldehyde (Glu) was attached to the electrode surface through Schiff base reaction with surface amine groups. The modification was completed by attachment of NB via Schiff base formation between the NB and immobilized Glu. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to trace the reactions in each step. The chemically modified electrode exhibited good electrocatalytic activity for both reduction and oxidation of H2O2. A significant decrease in over voltage for the reduction of hydrogen peroxide, as well as a drastic increase in the peak currents were observed in comparison with the bare GC electrode. These characteristics together with long-term stability, low detection limit, and high sensitivity of the modified electrode are highly promising for amperometric determination of hydrogen peroxide.