Enhanced Electrochemiluminescence of TiO2 Nanoparticles Modified Electrode by Nafion Film and Its Application in Selective Detection of Dopamine

In this work, a simple and effective approach to obtain stable, nontoxic and strong electrochemiluminescence (ECL) interfaces is provided by coating TiO₂ nanoparticles (NPs) modified glassy carbon electrode (GCE) surfaces with Nafion. Unlike a decrease of the current resulting from the blocked diffusion usually displayed in electrochemical processes by Nafion coating, a Nafion/TiO₂ NPs modified electrode not only shows a highly stable ECL, but also shows an 8‐fold increase of ECL intensity and a reduction of the overpotential of ca. 300 mV in the presence of K₂S₂O₈ as co‐reactant, compared with those of bare TiO₂ NPs modified electrodes. The roles of Nafion coating on TiO₂ NPs in the ECL process are proposed to be twofold: to provide refuge for the free radicals and to enhance the electron‐hole recombination. Benefiting from its excellent ECL performance, the cationic exchange function of Nafion and the susceptible to being oxidized performance of dopamine (DA) by holes, the Nafion/TiO₂ composite electrode could be used to sensitively and selectively detect DA with a detection limit of 1.0×10^?11 M and a linear range of 1.0×10^?11–6.0×10^?7 M. The coexisting anionic species such as excess ascorbic acid show little interference on DA detection.