Microwave synthesis of reduced graphene oxide decorated with silver nanoparticles for electrochemical determination of 4-nitrophenol

Abstract

A facile microwave-assisted synthesis of a reduced graphene oxide-silver (rGO-Ag) nanocomposite and its application towards the electrochemical determination of 4-nitrophenol (4-NP) are reported. The nanocomposite was characterized using UV–visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, and X-ray photoelectron spectroscopy (XPS). The formation of spherical AgNPs was confirmed from the single surface plasmon absorption feature and the TEM analysis. The reduction of GO was conveniently monitored using D and G band intensity ratio (ID/IG) of Raman spectrum and XPS analysis. A glassy carbon electrode (GCE) was modified with the rGO-Ag nanocomposite and used for the electrocatalytic reduction and determination of 4-NP. The nanocomposite modified electrode displayed a higher reversible redox peak currents and lower charge transfer resistance (Rct) towards [Fe(CN)6]3−/4− couple compared other controlled electrodes. The amperometric i-t curve response to 4-NP at a working potential of −0.52V (vs. Ag/AgCl) covers the 1–1100μM concentration range, and the limit of detection is 0.32μM. The sensor is selective for 4-NP even in the presence of 50-fold higher concentrations of analogues such as bromophenol blue, 2-amino-4-nitrophenol, 2-chlorophenol and 2,4-dinitrophenol. The nanocomposite modified GCE was successfully applied for the determination of 4-NP in spiked real water samples where it gave recoveries between 94.3% and 100.2% at a concentration level of 10–50μM.