Electrochemical determination of dopamine using a glassy carbon electrode modified with TiN-reduced graphene oxide nanocomposite

A composite comprising reduced graphene oxide (RGO) and titanium nitride (TiN) was fabricated via a combined two-step process of sol-gel and ammonia annealing. Transmission electron microscopy showed that TiN nanoparticles with a mean diameter of <10 nm were densely decorated onto the RGO surface. Cyclic voltammetry indicated that a glassy carbon electrode (GCE) modified with the RGO-TiN nanocomposite exhibited an excellent electrocatalytic activity toward the oxidation of dopamine in 0.1 M phosphate buffer solution (pH = 7). The combined use of RGO and TiN resulted in a higher current response and a lower oxidation potential (0.23 V) than those of bare GCE, RGO/GCE, and TiN/GCE. In addition, the developed electrochemical sensor showed a linear relationship with the dopamine concentration from 0.1 to 80 μM with a limit of detection of 0.012 μM (S/N = 3). The sensor demonstrated excellent selectivity, good stability, and reproducibility. The sensor was applied to the determination of dopamine in urine samples by the standard addition method and gave recoveries of 97.0-101.5%.