Fabrication of rGO/NiS/AuNCs ternary nanocomposite modified electrode for electrochemical sensing of Cr(VI) at utra-trace level

Abstract

In the present investigation, ternary nanocomposite of reduced graphene oxide rGO, Nickel sulphde (NiS) and gold nano cube (rGO/NiS/AuNCs) has been synthesized by adopting a facile single step hydrothermal method. The electrochemical interfacial property of the composite materials is obtained from cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The crystal structure, surface morphology and elemental composition of the rGO/NiS/AuNCs ternary nanocomposite are characterized using XRD, SEM and EDX measurements, the characterization of the materials using such techniques have shown the formation of flower shaped NiS and Au in the form of AuNCs, effective formation of composite has been evident from the microscopic and spectroscopic measurements. The square wave voltammetry technique is employed to the determination of Cr(VI) in 0.1 M acetate buffer solution at the optimized pH 5. The influence of various electrochemical parameters affecting the stripping voltammetry are investigated and optimized. Under optimal condition, the limit of detection (LOD) in the present method is found to be 0.09 µgL−1 at the accumulation potential of -0.5V for the duration of 30s. The rGO/NiS/AuNCs ternary nano composite modified electrode showed good stability and high sensitivity towards the detection of Cr(VI) with low response time. The developed method has been applied for the detection of Cr(VI) in environmental samples.