The enhanced electrochemiluminescence of luminol on the nickel phthalocyanine modified electrode

Abstract

A glassy carbon electrode (GCE) modified with nickel(II) tetrasulfophthalocyanine (NiTSPc) and Nafion^® was used for the investigation of the catalytic oxidation of luminol. The modified electrode was found to much more effectively improve the emission of electrochemiluminescence(ECL) of luminol in a solution containing hydrogen peroxide. The enhanced ECL signal corresponded to the catalytic oxidation of both luminol and H₂O₂ by NiTSPc. Attached Ni(II) on GCE was oxidised to Ni(III) and then used as the catalyst for the chemiluminescence of luminol. The enhanced stability of the ECL signal with Nafion^® would mainly result from the prevention of the dissolution of NiTSPc and the adsorption of the oxidation product of luminol on the electrode surface. The proposed method enables a detection limit for luminal of 6.0 × 10⁻⁸ mol L⁻¹ to be achieved in the presence of H₂O₂ in the neutral solution. The enhanced ECL intensity had a linear relationship with the concentration of luminol in the range of 1.0 × 10⁻⁷–8.0 × 10⁻⁶ mol L⁻¹