Two-dimensional layered rGO-MoS2 heterostructures decorated with Fe3O4 nanoparticles as an electrochemical sensor for detection of para-nitrophenol

In this study, reduced graphene oxide-molybdenum disulfide/iron oxide (rGO-MoS2/Fe3O4) nanocomposite, in which rGO nanosheets act as a substrate for Fe3O4 nanoparticles and the MoS2 nanostructure, was synthesized. The rGO-MoS2/Fe3O4 nanocomposite was synthesized with use of molybdenum disulfide, iron(III) chloride hexahydrate, and graphite oxide powder by application of the microwave method. The hexagonal structure of rGO-MoS2 along with the cubic geometry of Fe3O4 was confirmed by X-ray diffraction, while the decoration of the layered structure of rGO-MoS2 with Fe3O4 nanoparticles was visualized in scanning electron microscopy images of the nanocomposite. Increase in the intensity of the D band of the nanocomposite, when compared with rGO, in Raman spectra further indicated that the presence of Fe3O4 and MoS2 induced non-graphitic defects in the nanocomposite. The as-prepared sensor was applied for the electrochemical sensing of p-nitrophenol. Cyclic voltammetry was used to study the behavior of p-nitrophenol, while differential pulse voltammetry was used for a concentration study. Real samples of water, viz., distilled water, tap water, and river water, were used for this study. The detection limit obtained was 0.8 mu M, and good sensitivity of 0.71 mu A mu M-1 cm-2 was achieved. This study provides motivation for the use of nanocomposites of carbon and transition metal dichalcogenides over use of metal-based nanoparticles.