Cathodic electrochemiluminescent behavior of luminol at nafion-nano-TiO2 modified glassy carbon electrode

The electrochemiluminescence (ECL) behavior of luminol on a nafion-nano-TiO(2) modified glassy carbon electrode (nafion-nano-TiO(2)--GCE) was studied. Two ECL peaks (ECL-1 and ECL-2) were found during cathodic potential scanning. ECL-1 at ca -0.4 V (vs Ag--AgCl reference electrode) came from the reaction between luminol and active oxygen anion produced at the GCE surface directly, while ECL-2 at ca -0.9 V (vs Ag--AgCl reference electrode) came from the reaction between luminol and the active oxygen anion catalyzed by TiO(2.) The possible mechanism for the generation of both ECL peaks has been proposed. The reproducibility of the ECL intensities on nafion-nano-TiO(2)--GCE at ECL-1 and ECL-2 was good, with relative standard deviations (n = 10) of 4.3 and 1.3%, respectively. The ECL-2 generated at the nafion-nano-TiO(2)--GCE surface was further developed to detect the dissolved oxygen, and a detection limit of 0.02 mg/L was achieved. The proposed method was applied to detect dissolved oxygen in water with satisfactory result.