An OFF-ON detection method for copper (II) ion using AgAu-NG nanocomposites modified electrode
An OFF-ON detection method for Cu2+ was developed at the AgAu bimetallic nanoparticles decoration nitrogen-doped graphene (AgAu-NG) nanocomposites modified electrode. The measure was based on the copper-catalyzed oxidation of cysteamine (Cys) to regulate the oxidation peak current of Ag. In the absence of Cu2+, Cys can bind to the surface of AgAu-NG via Ag-S or Au-S bond, thus leading to an obvious decrease of the oxidation peak current of Ag. However, in the presence of Cu2+, Cu2+ can greatly catalyze the oxidation of Cys by dissolved O2 to form cystamine, which would fall off the surface of AgAu-NG, leading to partial recovery of the oxidation peak current of Ag. With the increase the concentration of Cu2+, the oxidation peak current of Ag in the presence of Cys increased accordingly. So, the concentration of Cu2+ can be measured. By using the optimum conditions, this method can detect Cu2+ concentrations down to 0.3 nM (S/N = 3) with linear response range of 1 nM-1mM. Furthermore, this method was applied to determine Cu2+ in river water samples and showed excellent analytical performance.