Small Molecular Regulated Electrodeposition Of Precious Metal Nanoparticles And Their Application To Electrocatalytic Oxidation

This thesis is mainly about the application of electrodeposition method on the synthesis andpreparation of precious metal nanomaterials. By studying the effect of the electrodeposition potential andtime, as well as the guiding agent and its concentration, morphology and size-controlled synthesis of metalnanomaterials can be realized. And we further study their catalytic activity. Through discussing theinfluence of these factors on the morphology of metal nanomaterials, simple, well-controlled,good-repeatable and efficient synthetic route is probed. This laid the foundations for future synthesis ofother precious metal nanomaterials, so it has important theoretical and practical value.This thesis mainly focused on controlling the electrodeposition of precious metal nanomaterials byemploying different small moleculars, and fabricating electrochemical sensor. For the purposes, we carriedout the following four aspects of the work:1. The shape control of Au nanocrystals is crucial to their catalytic applications and optical properties.Well-defined “clean” Au nanodendrites (NDs) have been prepared on a glassy carbon electrode usinglow-potential synthesis, assisted by ethylenediamine (EDA). The effects of applied potential, depositiontime, and HAuCl4(or EDA) concentrations on the morphology of the Au deposits are discussed in ourwork. The growth mechanism can be explained by a two-staged growth of dendrites: initial branching andsubsequent dendritic growth. The Au NDs exhibits superior catalytic performance toward ethanol oxidation,in comparison with the polycrystalline Au nanoparticles. The simple and facile synthetic technique can beapplied to the construction of other metals with complex hierarchical structures on a large-scale.2. With the help of cytosine, it is very easy to make preparation of flowerlike Au NPs on a glassycarbon electrode (GCE) by the method of one-step and template-free electrodeposition. The resultsdemonstrated that the electrolyte and its concentration, the electrodeposition potential, and theelectrodeposition time were crucial for the formation of the flowerlike Au NPs. The resulting flowerlike AuNPs electrode showed good electrocatalytic activity toward the oxidation of methanol. Evidently, theas-prepared flowerlike Au nanoparticles have potential or practical applications in the fields of electronics,biomedicine catalysis, sensors and SERS.3. A facile, three-step and template-free electrodeposition method has been developed to prepare agglomerate Ag nanostructures. It was found that the morphologies of the obtained Ag displayedmonodispersed agglomerate nanoparticles by the scanning electron microscopy (SEM) technique, andfurther structurally characterized using the X-ray diffraction (XRD) and electrochemical methods.Furthermore, the obtained agglomerate Ag nanoparticles showed higher electrocatalytical oxidation towardCSH through the cyclic voltammetry experiments. It was noticed that the Ag nanoparticles electrodepositedat0V (vs. Ag/AgCl) exhibited higher electrocatalytical performance in comparison with those formed atother potentials. The silver nanometer has high compared to the surface area and the surface activity, in thephotoelectric apparatus, the catalyst material, low temperature aspects and so on superconducting material,against static electricity material, electronic pulp and biosensor material has the widespread application.4. A facile, one-step and template-free method has been developed for the electrodeposition ofwell-dispersed platinum nanoparticles (Pt-NPs) on a glassy carbon electrode. The effects of variousinorganic anions and overpotential on the morphologies and dimensions of the final products wereinvestigated. The resulting Pt-NPs show high electrocatalytic activity towards methanol oxidation and areless easily poisoned by carbon monoxide. The obtained Pt NPs had superior performance in the catalyticactivity, antiposion, and stability towards the methanol oxidation, which have potential or practicalapplications in the fields of fuel cells, electrode materials, energy, and catalysts.