Controllable Electrochemical Preparation Of Gold And Platinum Nanostructures And Their Electrocatalysis Towards Methanol

Nanomaterials are different from traditional materials due to their uniqueproperties, such as electronics, optics, magnetism, mechanics etc., and used widely inthe fields of biochemical sensing, chemical power, electronic devices and magneticstorage. Currently, there are various methods to produce nanomaterials, whereelectrodeposition as a simple, easy method becomes very popular. This thesiselectrochemically synthesized morphology-controllable Pt and Au nanostructures, andstudied their electrocatalytic activities towards methanol, as summarized below.1. Flower-like Pt cubes were fabricated with assistant of non-fixed SiO2microsphere film as a template. Scanning electron microscopy was employed tocharacterize morphology and size of the resultant particles. The formation mechanismwas discussed by studying the effect of various factors, such as the electrolyteconcentration, the growth time, and the thickness of SiO2microsphere film. The resultsalso found that SiO2colloid particles as a non-fixed template affected thenanostructure of as-prepared Pt material by changing the mass transfer process.2. Three-dimensional hydrangea macrophylla flower-like Pt nanostructures (3DPHNs) were produced by a chronopotentiometric technique. The morphology andstructure of as-prepared3D PHNs were further characterized by scanning electronmicroscopy (SEM), high-resolution transmission electron microscopy (HRTEM).Different platinum nanostructures produced under different current densities presentedvarious electrocatalytic activities. The optimized3D PHN obtained at the currentdensity of3.5mA cm2showed better electrocatalytic activity and stability to methanoloxidation than the commercial Pt/C catalyst, which may be attributed to the abundanceof Pt(111) facets.3. Three dimensional dendritic gold nanostructures (3D DGNs) were prepared bychronoamperometric technique involving glycine (Gly) as an additive. Scanningelectron microscopy (SEM) and high resolution transmission electron microscopy(HRTEM) were applied to characterize the morphology and structure. The resultsfound that many factors, such as Gly concentration, applied potential, and the nature ofsubstrate effected the morphology. The optimized3D DGN obtained at0.1V with10.0mmol dm3of glycine showed the best electrocatalytic activity and tolerance tomethanol.