Study Of Fabrication And Properties Of Micro-nano Structured Gold Films From Electrodes Of Gold And Gold Alloys By Square Wave Potentials

Gold nanostructures have received considerable attention in many fields such as chemical engineering, energy sources, electronics. Different forms of gold nanomaterials have been prepared by various methods. Thereinto, electrochemical technique is a promising method and has several advantages such as easy control, mild condition, little pollution and wide application. In this thesis, a novel, simple and rapid electrochemical method on the fabrication of three-dimensional dendritic/porous gold film electrodes is presented. The as-prepared dendritic/porous gold films have promising applications in electrocatalysis, surface enhanced Raman spectroscopy and hydrophobicity. The main contents are as follows:1. A novel electrochemical method to prepare dendritic gold nanostructures has been described. Namely, multifunctional dendritic gold (DG) nanostructures have been synthesized facilely by square wave potential pulse (SWPP) with an Au45Sn55 (wt.%) alloy in an electrolyte of NaOH or H2SO4. The dendrite formation involves combined actions of selective removal of Sn, oxidation-reduction cycles (ORCs) of gold and intensive hydrogen evolution. The prepared DG has good performance in electrocatalytic oxidation of glucose, surface-enhanced Raman scattering, and superhydrophobicity. And a longer time is required to get similar dendritic structures in acidic conditions.2. For an alloy of Au80Sn20, three-dimensional porous gold film formed in the case of gas releasing and irregular gold grain film generated otherwise. The porous gold film has excellent electrocatalytical activity for the oxidation of glucose or ethanol. The surface of the porous gold nanostructure shows superhydrophobicity after being assembled with n-dodecanethiol monolayer. DG film can also be prepared with the Au80Sn20 alloy in an electrolyte of H2SO4 in the case of no gas releasing.3. SWPP treatment of pure gold, as well as AuNi, AuAg, AuCu electrodes has also been investigated. DG can be fabricated in an electrolyte of H2SO4 in the case of no gas releasing and irregular gold grain film in an electrolyte of NaOH. Micro/nano structures can also be produced with electrodes of AuNi AuAg, AuCu alloys by the means of SWPP.