Bifunctional impedimetric sensors based on azodicarboxamide supported on modified graphene nanosheets

•We have demonstrated the suitability of GC/GO/AuNPs/ACA as an ideal catalyst toward iodate reduction and cysteine oxidation.•The proposed sensor has significant advantages of low over potential, high current density and sensitivity, good reproducibility and stability.•It can be used as an impedimetric electrochemical sensor for monitoring iodate and cysteine.

Herein, gold-coated graphene oxide nanosheets hybrid material (GO/AuNPs) with exceptional physical and chemical properties has been utilized as a novel platform for electrode modification. The synthetic method of GO/AuNPs involves anon-covalent functionalization of exfoliated GO with AuNPs based on the reduction of the Au(III) complex by sodium citrate. The prepared GO/AuNPs hybrid exhibits the dispersion of high density AuNPs which were densely decorated on the large surface area of GO. The GO/AuNPs modified glassy carbon (GC) electrode was employed as a sensing platform to immobilize azodicarboxamide (ACA). The morphology, structure and electrochemical performance of the sensor were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that the modified electrode has a notable bifunctional catalytic activity. Electrocatalytic oxidations of cysteine and electrocatalytic reduction of iodate at the surface of modified electrode were investigated with different technique.

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