Enhanced Cathodic Electrogenerated Chemiluminescence of Luminol at a Graphene Modified Electrode in Neutral Solution

Abstract

Graphene oxide (GO) and electrochemically reduced graphene (ERG) modified glassy carbon electrodes (GCE) were prepared and characterized by FT-IR, scanning electron microscopy (SEM), and electrochemical techniques, respectively. Electrogenerated chemiluminescence (ECL) of luminol was studied on the modified electrodes in neutral phosphate buffer solution (PBS). Either at the GO modified electrode or at the ERG modified electrode, the anodic ECL emission of luminol was inhibited greatly and only one cathodic ECL peak was obtained. The intensity of the cathodic ECL emission at the ERG modified electrode increased 123 times compared with that of the GO modified electrode or the bare electrode, which is due to the strong adsorption of dissolved oxygen by ERG film. Several impact factors of luminol ECL, such as the electrochemical reduction potential, the duration of the applied reduction potential, the pH values, the supporting electrolytes, and the potential scan rate were studied and the mechanism of the cathodic luminol ECL emission on the ERG modified electrode was proposed.