Self-assembly Of Au And Au/Pt Core/Shell Nanoparticles For Methanol Electro-oxidation

Noble metal nanoparticles have broad application prospects in many fields suchas communication, electrocatalysis, electronics and sensing owning to their uniqueoptical, electrical, and magnetic properties different from bulk counterparts. However,to achieve in various aspects, nanoparticles need to be used as building blocks toconstruct2-dimensional（2D） or3-dimensional（3D） nanostructures. Self-assembly as asimple and convenient method has been widely employed to fabricate2D thin-filmand3D nanocrystals for many substances, the properties of which could be tunedeasily by controlling their fine structures. Thus, this thesis involved self-assembly ofgold nanospheres and Au/Pt core/shell nanopspheres at oil/water interface, and Au/Ptcore/shell nanosphere monolayer films for methanol electro-oxidation. The maincontents are summarized as follows:1. Self-assembly of gold nanospheres.Au nanosphere assemblies with different structures such as ring, microsphericalnanocage were obtained by n-butanol-mediated method involving adding toluene andn-butanol into18-nm-Au colloid under vigorous mixing. The resultant structures ofassemblies were related to temperature, types of surfactants and the volume ratio ofoil（i.e. toluene+n-butanol） to water. This study expands the types of Au nanoparticleassemblies.2. Synthesis of Au/Pt core/shell nanospheres and nanorods.Gold nanospheres of¹8nm and³.5nm and nanorods with the average aspectratio of3.5were used as seeds respectively to prepare Au/Pt core/shell nanospheresand nanorods by reducing H₂PtCl₆with ascorbic acid（AA）. Au/Pt core/shellnanospheres and nanorods with different Pt shell thicknesses were synthesized byadjusting the amount of gold seeds and the concentration of H₂PtCl₆precursorsolution.3. Au/Pt core/shell nanosphere monolayer films for methanol electro-oxidation.Au/Pt core/shell nanosphere monolayer films fabricated by then-butanol-mediated interfacial assembly method were transferred ontoglassy-carbon（GC） surface for methanol electro-oxidation. The results indicated thatthe monolayer catalysts showed superior catalytic activities. Under the optimizedcondition, the mass activity of Au/Pt monolayer film is about6.5times as good as that of com-mercial Pt/C catalyst and far better than Au/Pt core/shell nanosphere catalystfabricated by the drop-coated method. This superior electrocatalytic performance ismainly ascribed to monolayer assembly for fully exploiting Pt species and synergisticeffect between Au and Pt.