Preparation And Investigations On Metal-Based Nanostructured Electrode Materials

Metal nanostructured materials have been studied extensively because of their unique physical and chemical properties. They have been widely used in multiple fields such as electrics, optics, catalysts and sensors. They have gradually received attentions when they applied in electroanalysis and sensor areas due to their larger specific surface area, higher catalytic activity and excellent electronic conductivity.In recent years, peculiar properties that differ from their individual constituent were found in metal composite nanostructured electrode materials, including high catalytic activity, catalytic selectivity and better resistance to deactivation. As a representative of metal nanocomposites, core-shell nanostructured materials process high stability, excellently catalytic and optical properties, and have been extensively applied in various fields. However, only few reports recently emerged concerning their applications in catalysis and sensor fabrication. Supporting matrices are also important in fabrication of composite nanostructured electrode materials due to their significant effects on the resulting materials'performances. Systematic studies demonstrated that multi-walled carbon nanotubes is an excellent candidate of supporting materials due to the high effective surface area, good electron transferring function and chemical stability. Moreover, it was reported that properties of metal nanostructured electrode materials could be modified through changing the component, grain size, texture and the surface profile, hence, developing novel nanostructured electrode materials with improved catalytic and sensing performances is very important for further application. Compared with other methods, electrodeposition methods are promising in achieving novel nanostructured electrode materials with advantages of high purity of the particles and controllability of particle size by adjusting the condition of electrolysis. The determination of glucose has been widely investigated in view of its clinic importance, biotechnology and food industry. Hydrogen peroxide is found to be a common intermediate in both environmental and biological systems and is a product of the oxidation of glucose by GOx. Thus, investigations on developing novel electrode materials available for detection are of interest and attract considerable attention. Metal-based nanostructured electrode materials are of particular interest for non-enzymatic glucose and hydrogen peroxide detection owing to the ease of preparation and high electrocatalytic ability.In this research, attention is paid on the preparation of a series of metal-based nanostructured electrode materials by chemical and electrochemical methods. The electrocatalytic properties of these electrode materials and their applications in sensor fabrication were investigated in detail. This work was mainly consisted of following three parts:In the first part, core-shell structured Au@Pt electrode materials was prepared by seeded growth approach and demonstrated for the first time as active electrode material for non-enzymatic determination of hydrogen peroxide and glucose. The morphology of Au@Pt nanoparticles was confirmed by scanning electron microscopy (SEM), revealing a cylindrical shape of the Au nanorods dotted with small Pt nanodots at endcaps and edges. Catalysis and assay performances of Au@Pt electrode materials were evaluated in detail. Cyclic voltammetry (CV), chronoamperometry (I-t) revealed a high sensitivity, excellent stability, and good reproducibility in the hydrogen peroxide and glucose determination.In the second part, copper nanostructured electrode materials were prepared by electrodeposition at high overpotentials in acid condition, in which, the process of copper electrodeposition was competitive with the process of hydrogen evolution. The morphologies and structures of the copper nanostructured electrode materials were characterized by SEM. Results revealed that hydrogen evolution greatly affected the morphology of copper electrodeposits, and well-dispersed copper nanostructured materials were achieved. The glucose electrooxidation activities on the electrode materials were largely dependent on the electrodeposition condition parameters. Under optimal conditions, the electrodeposited copper nanostructured electrode exhibited fast response, high sensitivity, wide linear range, low detection limit and excellent resistance towards electrode fouling to the oxidation of glucose. Present study provides a low cost and simply controlled test-bed for the fabrication electrode materials for non-enzymatic glucose sensors.In the third part, the multi-walled carbon nanotubes film supported copper nanostructured electrode materials was prepared by two-step electrodeposition. A stable copper/CNT composite film electrode with high electrocatalytic activity to glucose was obtained.