Preparation And Electrochemical Studies Of The Novel Modified Materials——Graphene Oxide, Graphene

Carbon materials, due to the high electrical conductivity and the excellent electrocatalysis, have become the most widely used electrode materials in the field of electrochemical analysis. In view of the fact that graphene has very special physical and chemical properties such as:the large specific surface area, a zigzag edge, the high electron mobility rate at room temperature, more and more researchers in scientific community are joining in the research and synthesis of the graphene. Graphene Oxide (GO), as well as the oxidation product grapheme, is an intermediate of the Graphene preparation by chemical reduction. And it is an important member of the graphene derivatives family. The biggest difference between GO and graphene is that there are abundant active oxygen-containing groups on the surface of GO molecular slice. These oxygen-containing groups bring some properties such as: evenly dispersed in the water and the higher electron mobility rate. There are so many scientists in scientific community joining in the research of the graphene and GO in recent years. However, the report about the comparison research between GO and graphene has not emerged yet. In this paper, the electrochemical properties of the graphene with the GO were compared based on the status quo.1. The GO was prepared by graphite oxide reduction method (improved Hummers method) with the aid of ultrasonic. Then the oxygen-containing groups were removed by chemical reduction-the hydrazine hydrate reduction method. The morphological characterizations and physical properties of graphene and GO were confirmed by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscope (AFM). Results showed that there are more abundant active oxygen-containing groups on the slice layer surface of GO than that of the graphene. Meanwhile, the molecular slice of the graphene exhibited drape, while the plane structure of the GO was flat and level. These all proved that graphene and GO were successfully composed.2.In this paper, the graphene and GO, accompanied with nafion, were used to construct electrochemical sensor, and the modified electrodes (Nafion/graphene/GCE and Nafion/GO/GCE) were applied for the determination of metal ions Pb2+in water. Differential pulse anodic stripping voltammetry (DPASV) was adopted to investigate the analytical performance of Nafion/graphene/GCE and Nafion/GO/GCE to lead (Pb2+). It turned out that the Nafion/GO/GCE showed a better performance for the determination of Pb2+than Nafion/graphene/GCE. the detection limit of Nafion/graphene/GCE and Nafion/GO/GCE is1.0×10-7and2×10-8mol L-1. These all proved that the GO modified electrode had better adsorption effect to the metals contrasting with the graphene. In addition, the stability of Nafion/GR/GCE was better than that of Nafion/GO/GCE.3. The electrochemical detection and possible mechanism of aminophenol was studied on Nafion/graphene/GCE and Nafion/GO/GCE using square wave voltammetry (SWV). Results showed that the redox reaction mechanism of aminophenol was consistent on the two sensors, while the detection limit of aminophenol on Nafion/graphene/GCE was half an order of magnitude larger than that of Nafion/GO/GCE. This possible reason might that the oxygen-containing groups on the surface molecular slice of GO improved the electron transfer rate the electrode surface.