Enhanced Electrochemiluminescence of TiO_2 Nanoparticles' Modified Electrode by Nafion Film and Its Application in Selective Detection of Dopamine

摘要

In this work, a simple and effective approach to obtain stable, nontoxic and strong electrochemiluminescence (ECL) interfaces is provided by coating TiO_2 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/TiO_2 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 K_2S_2O_8 as co-reactant, compared with those of bare TiO_2 NPs modified electrodes. The roles of Nafion coating on TiO_2 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/TiO_2 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.