A novel approach to fabricate stable graphene layers on electrode surfaces using simultaneous electroreduction of diazonium cations and graphene oxide

Abstract

The short time fabrication of graphene layers on glassy carbon (GCE) and indium tin oxide (ITO) electrodes by simultaneous electroreduction of graphene oxide (GO) and diazonium salts was described for the first time. Initially, aminotriazine groups were introduced on the electrode surface by an in situ process of a diazotization protocol using melamine. Subsequent electrochemical reduction of diazonium groups immersed in GO solution leads to the formation of graphene layers on the electrode surface. Using this methodology, stable graphene layers were fabricated within 10 min on the electrode surface. The simultaneous reduction of triazine diazonium cations and GO and the formation of graphene layers on the electrode surface were confirmed by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and cyclic voltammetry (CV). The absence of characteristic peaks in XPS for the diazonium group (403.7 and 405.6 eV) and oxygen functionalities confirmed the reduction of the triazine diazonium cations and GO on the electrode surface. Raman spectra reveal that the intensity ratio of D and G bands (1340 and 1584 cm⁻¹) was increased after the electrochemical reduction of GO. The SEM image shows the formation of thin layers of graphene. Impedance studies indicate that the electron transfer reaction of [Fe(CN)₆]^3−/4− was higher at the graphene modified electrode (4.10 × 10⁻⁴ cm s⁻¹) than at bare (3.77 × 10⁻⁵ cm s⁻¹) GC electrode. The electrocatalytic activity of the graphene modified electrode was examined by studying the oxidation of dopamine (DA). The graphene modified electrode not only increased the oxidation current of DA enormously but also shifted its potential towards a less positive potential when compared to bare and GO modified GC electrodes. The present strategy of modification of graphene is simple and requires a very short time.