Enhanced Performance of GCE/N-Reduced Graphene Oxide-Au Nanocomposite in Dopamine Sensing

The reduced graphene oxide (rGO) and nitrogen-reduced graphene oxide (N-rGO) were electrochemically coated with gold nanoparticles and compared as the modifier of a glassy carbon electrode (GCE) for dopamine (DA) electrochemical sensors. The rGO and N-rGO were prepared by reduction of graphene oxide (GO) under hydrothermal conditions. Urea was applied as a nitrogen dopant. The modified GCEs were tested as working electrodes in the electrochemical DA detection in the presence of ascorbic and uric acids. Initially, the working parameters of sensors in a pure dopamine solution were determined. The GCE/N-rGO-Au electrode exhibited a lower limit of detection compared with the GCE/rGO-Au (385 vs. 700 nM). Both sensors had a wide linear range of 1-100 µM and high sensitivity of 0.78 µA/µM for GCE/N-rGO-Au and 1.78 µA/µM for GCE/rGO-Au. The presence of ascorbic and uric acids in the solution resulted in a decrease in the intensity of DA oxidation peak, maintaining acceptable limit of detection. This study showed that the surface modification of the graphene materials with gold nanoparticles allows to obtain satisfactory working parameters of DA sensors. The GCE/N-rGO-Au demonstrated the superior performance in DA sensing due to a homogeneous distribution of gold nanoparticles on the surface of the N-doped graphene material.