Fabrication of graphene–gold nanocomposites by electrochemical co-reduction and their electrocatalytic activity toward 4-nitrophenol oxidation

A mixture of graphene oxide and tetrachloroauric acid were directly electrochemical co-reduced on a glassy carbon electrode (GCE) through cyclic voltammetry (CV). A graphene–gold nanocomposite film modified GCE was fabricated and used to investigate the electrochemical behavior of 4-nitrophenol by CV, electrochemical impedance spectroscopy, chronocoulometry and linear sweep voltammetry. Compared with the bare GCE and the gold nanoparticles modified GCE, it was found that the oxidation signal of 4-nitrophenol was remarkably improved at the graphene–gold nanocomposite film modified GCE. The experimental parameters such as the types of buffer solutions, the pH of supporting electrolyte, the amounts of deposits, the accumulation time and potential were optimized. Under the optimum experimental conditions, the oxidation peak currents were proportional to the 4-nitrophenol concentration in the range of 3.6 × 10−8–9.0 × 1 0−5 M with a detection limit of 1.0 × 10−8 M (S/N = 3). The modified electrode which presented high sensitivity, good repeatability and stability was applied to the direct determination of 4-nitrophenol in river water samples.