Preparation Of Graphene Based Composite Materials And Construction Of The Non Enzymatic Glucose Sensors

Graphene, only one atom thick and composed of sp2-hybridized carbon atom, is a two-dimensional slice of a honeycomb structure. Graphene is the ideal catalyst carrier, which has excellent electrical, thermal, optical and mechanical properties because of its very large surface area, so graphene and its composites have received great attention of most researchers recently. Diabetes is the worldwide, common and third largest dangerous disease only next to cancer and cardiovascular disease. So the accurate and quick detection of glucose levels of human blood has extraordinary significance for the early diagnosis and treatment of diabetes. Glucose sensors included enzyme and nonenzyme sensor, the latter shows a good electrocatalytic activity than the former because of enzyme sensor being affected easily by external factors for long-term storage. Overall, the nonenzyme sensor has the advantages of wide linear range, low detection limit, high sensitivity, good selectivity, and showed good reproducibility and long-term stability. So the study of non enzyme glucose sensing has attracted a wide attention. The main contents can be summarized as follows:1. We proposed a facial solvothermal approach to the in situ decoration of nickel oxide nanoparticles on the surface of solvothermal reduced graphene(Ni O@SRG). The high dispersion of Ni O nanoparticles with the uniform size distribution could be easily obtained via using simple solvothermal process. Moreover, the as-prepared Ni O@SRG modified glassy carbon electrode(GCE) exhibited better non-enzymatic electrocatalytic responses towards glucose detection and the limit of detection is 1.15 μM(S/N= 3) in alkaline media. In addition, this electrode material possessed some important advantages such as low cost, easy preparation, good stability and high reproducibility.2. We proposed a simple and effective approach to the in situ decoration of Cu2 O nanoparticles on the surface of graphene nanosheets(Cu2O@CRG). The microstructure and morphology of Cu2O@CRG were characterized by atomic force microscopy(AFM), transmission electron microscopy(TEM), energy-dispersive X-ray(EDX) and X-ray powder diffraction(XRD) spectroscopy. The results confirm that the high dispersion of crystal Cu2 O nanoparticles with the uniform size distribution could be easily obtained via using sodium citrate as reductant and stabilizer. Moreover, the as-prepared Cu2O@CRG modified glassy carbon electrode(GCE) exhibited a better non-enzymatic electrocatalytic response to glucose than the chemically reduced graphene(CRG) or Cu2 O in alkaline media.3. Graphene supported platinum nanoparticles composites(Pt@G) and nitrogen-doped graphene supported platinum nanoparticles composites(Pt@NG) are prepared by chemical reduction and characterized by TEM, AFM, XPS and XRD. The results showed that platinum nanoparticles dispersed homogeneously on the surface of graphene and nitrogen-doped graphene with the uniform size. Pt@NG modified electrode had a bette catalytic effectivity than Pt@G and presented a good linear relationship and higher detection sensitivity to glucose in alkaline media from the electrochemical experiments. Moreover, K2HPO4, Na Cl, KH2PO4, sodium Citrate, DA and AA had little effect on the detection of glucose.4. This chapter presented a route to synthetize Bi2O3@G. SEM, TEM and AFM were used to characterize the structure and morphology of this composites. The results indicated that Bi2O3@G also had folds, similar to the graphene oxide sheets. Bismuth trioxide nanoparticles dispersed homogeneously on the surface of graphene. Moreover, the electrochemical experiment showed that Bi2O3@G modified electrode possessed more effective than the graphene for oxidizing glucose, and the oxidation peak current and peak potential increased as the scanning speed enhanced. The process was controlled by diffusion because of the oxidation peak current showing a good linear correlation with the square root of scanning rate.