Study On Glucose Electrochemical Biosensing And Methanol Electrocatalysis Based On Noble Metal/Carbon Nanotubes

In recent years, diabetes incidence have grown noticeably and can not be completely cured, becoming a chronic disease and posing serious threat to human health. Therefore, the detection of glucose level in human blood is very important to the diabetes diagnosis and control. Electrochemical biosensors are widely used in sensing field due to its advantages of high sensitivity, high selectivity, low detection limit, easy miniaturization, fast response time etc. Exploring new kinds of electrode modified materials which have excellent detection performance has been one of the focus areas because the electrochemical biosensor performance is decided by the property of electrode modified materials. In addition, direct methanol fuel cells, as a new energy device, have attracted wide attention owing to its high energy conversion efficiency and non-pollution. However, the insufficient resources of high-performance anode catalyst (Pt) limites its commercialization. Therefore, the preparation of anode catalysts with high catalytic performance is an important research topic in the field of direct methanol fuel cell.New carbon nanomaterials (carbon nanotubes and graphene etc.) are used as supporting materials to construct high-performance composite catalysts on account of its excellent physical and chemical properties and nanosize effect etc. In order to improve the catalytic property of the catalysts, new carbon nanomaterials are modified to load other kind of nanomaterials with high dispersion and small particle size. The thesis focused on the preparation of nobal metal nanoparticles/carbon nanotubes composites and their application to glucose electrochemical biosensing and direct methanol oxidation. The main points are summarized as follows:(1) Using phenylphosphonic acid (PPA) functionalized carbon nanotubes (PPA-CNTs) as supporting material, the pre-synthesized platinum nanoparticles (Pt NPs) were uniformly anchored on the PPA-CNTs surface (Pt NP/PPA-CNTs), after which Pt NP/PPA-CNTs were used to load glucose oxidase (GOD). The obtained GOD/Pt NP/PPA-CNTs composites were applied as electrode material in glucose electrochemical biosensing. PPA-CNTs were characterized by solubility, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). The micrograph of Pt NP/PPA-CNTs nanocomposites and the electrocatalytic properties to glucose were characterized by transmission electron microscope (TEM), cyclic voltammetry (CV) and chronoamperometry (i-t), respecively. The results showed that fuctionalization process does not destroy CNTs structure and Pt nanoparticles were more evenly dispersed on PPA-CNTs surface than pristine CNTs. Based on the excellent electrochemical oxidation of Pt NP/PPA-CNTs composites to hydrogen peroxide (H2O2), the fabricated GOD/Pt NPs/PPA-CNTs biosensor demonstrated satisfactory glucose detection property.(2) Phenylphosphonic acid (PPA)-assisted one-pot method for preparation of PtRu nanoparticles with high dispersion and stabilization on carbon nanotubes (CNTs) is showed. Based on the ?-? stacking between phenylphosphonic acid and CNTs, abundant phosphonate groups were uniformly introduced on CNTs' surface, which significantly not only improve the solubility and dispersibility of CNTs in polar solvents but also enhance the dispersion of PtRu nanoparticles on CNTs' surface. The obtained PtRu/PPA-CNT electrocatalysts are characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), and X-ray powder diffraction (XRD). The results reveal that CNTs were successfully functionalized by PPA, and PtRu nanoparticles were uniformly dispersed on PPA-CNT surface with average particle diameter of 2.5 nm. Electrochemical studies certified that PtRu/PPA-CNT electrocatalysts have much higher electrocatalytic activity and stability for methanol oxidation in comparison with PtRu nanoparticles supported on the pristine CNTs because of their high electrochemical surface area at 612.7 cm2mg-1.