Synthesis And Application Of Canbon Nantubes Nanocomposite In Electrochemical

Canbon nantubes nanocomposites have drawn much attention by scientific researchers because they not only show their unexpected combined properties of the original components, but also cause changes in optical, chemical, or other performances compared with those of the individual components. The synthetic method of these materials has great influences on their electrocatalytic application. Thus, improving the traditional preparation process of nanomaterials is very important. In this thesis, simple and effective methods were developed to synthesize several kinds of representative canbon nantubes nanocomposites including NiO/MWNTs, CeO2/MWNTs, Pt/MWNTs and Pd/MWNTs. The excellent electrocatalytic activity of these materials indicates potential applications in biosensors and fuel cells. The following researches have been carried out.1. A novel matrix, multiwalled carbon nanotubes supported nickel oxide nanoparticles composite nanomaterial (NiO/MWNTs), for immobilization of protein and biosensing was designed using a simple and effective hydrothermal method. Using myoglobin (Mb) as a model, the direct electrochemistry of immobilized Mb indicated the matrix could accelerate the electron transfer between protein's active sites and the electrode. The modified electrode shows excellent electrocatalytic activity toward the reduction of H2O2 without the help of an electron mediator. The simple operation, fast response, acceptable stability, and reproducibility of the proposed biosensor indicated its promising application in protein immobilization and preparation of the third generation biosensors.2. A novel myoglobin-based electrochemical biosensor was developed. It is based on a nanocomposite prepared from multiwalled carbon nanotubes that were coated with ceria nanoparticles. UV-vis and electrochemical measurements displayed that the nanocomposite provides a biocompatible matrix for the immobilization of myoglobin (Mb) and also facilitates direct electron transfer between its active center and the surface of the electrode. Immobilized Mb exhibits excellent electrocatalytic activity toward the reduction of hydrogen peroxide (HP). The low apparent Michaelis-Menten constant of 63.3μM indicates high bioactivity and enhanced affinity to HP. This study also shows that the nanocomposite is a promising support for immobilization of proteins and for the preparation of third-generation biosensors.3. A novel approach to the synthesis of mono-dispersed platinum nanoparticles (Pt NPs) on multiwalled carbon nanotubes (MWNTs) has been proposed. With this method, we successfully assembled mono-dispersed Pt NPs on MWNTs. The method involved the in situ high-temperature decomposition of the precursor, platinum (Ⅱ) acetylacetonate (Pt(acac)2), in liquid polyols. We used X-ray diffraction, scanning electron microscopy, and transmission electron microscopy to characterize the resulting MWNTs covered with Pt NPs (Pt/MWNTs). We found that the size of the Pt NPs and the coverage density on MWNTs could be tuned easily by changing the reaction temperature and the initial mass ratio of Pt(acac)2 to MWNTs. Electrocatalytic measurements showed that the Pt/MWNTs had excellent catalytic activities in the electrooxidation of methanol and in the oxygen reduction reaction. These Pt/MWNTs have potential applications in fuel cells and biosensors.4. Nearly monodisperse palladium nanoparticles (Pd NPs) have been successfully decoration of multiwalled carbon nanotubes (MWNTs) by in situ high-temperature decomposition of the precursor Pd(acac)2 and MWNTs in liquid polyols. X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometer were used to characterize the final products, indicating the feasibility of our methods for synthesis of Pd/MWNTs nanocomposite. Electrocatalytic characterization demonstrated that these Pd/MWNTs have excellent catalytic activities in the electrooxidation of methanol, formic acid and hydrogen peroxide. The in situ synthesised Pd/MWNTs system displayed good electrochemical activity, with promising applications in fuel cells and biosensors.