Fabrication And Electroactivity Of Novel Nanoporous Au And Bimetallic Au-Ru Electrocatalysts

We all know that, since the end of 20th century, the electrocatalytic oxidation of small molecules has been receiving extensive investigation. The electrocatalytic oxidation process is of significant application both in fundamental research as model systems and in the fuel cells (FC). Small molecule electrocatalytic oxidation on noble metals has been widely studied. Development of electrocatalysts with significantly activities was a much challenging problem.Hydrothermal method as a soft chemistry method, has been applied to preparing the novel electrode materials in this paper. The electrocatalytic properties of electrocatalysts made by hydrothermal method are different from that by the traditional method. Novel titanium-supported gold electrodes were synthesized in this paper. Electro-catalytic activities of the electrodes were investigated by voltammetric responses, chronoamperometric measurements and electrochemical impedance spectra, etc. The main contents are as follows:1. The electrooxidation mechanism of glucose, hydrazine and formaldehyde was elaborated. The application of gold electrodes and small molecules electrooxidation are reviewed briefly.2. The electrodes were synthesized by the hydrothermal process.3. To investigate the morphology and element compositions of the electrodes obtained by the hydrothermal process, scanning electron microscopy and energy disperse spectroscopy are employed in the process. SEM and EDS images of nanoAu/Ti show that the surface of Ti substrate is covered by gold particles. The gold particles were present as small balls with a size of around 300nm. The gold particles are connected with each other and form 3D structures. The surface of the Au-Ru/Ti was covered by dentritic particles. The roughened surface of the dentritic particles is made up of variform flakes protruding from the surface. These flakes exhibit a variety of shapes but they have a similar thickness of ca. 30～35 nm. The presence of nanoporous features and the protruded flakes results in the high surface area of the Au-Ru/Ti catalyst.Using an electrochemical deposition technique, the titanium-supported Au/Ti electrodes are fabricated using HAuCl4 solutions as raw materials. Results show that the electrode presented high catalytic activity for glucose (hydrazine, formaldehyde) oxidation.4. Cyclic voltammetry, pseudo-steady state polarization, chronoamperometry and electrochemical impedance spectroscopy (EIS) were used to study the electrooxidation of glucose (hydrazine, formaldehyde) in sodium hydroxide solution on the nanoAu/Ti electrode.(1) It can be seen from CVs in alkaline solutions that the nanoAu/Ti electrodehas high catalytic activity for glucose (hydrazine, formaldehyde) oxidation. Compared to the polycrystalline Au electrode, the onset potential for oxidation of glucose (hydrazine, formaldehyde) was more negative on the nanoAu/Ti. From chronoamperometric measurements, we find that the steady-state current on the nanoAu/Ti was high and without pronounced decay, indicating the high stability of the nanoAu/Ti electrode in the electrooxidation process.(2) Electrochemical measurements show that Au99Ru5/Ti electrode presented highest catalytic activity for glucose oxidation. The different catalytic activity gives evidence of the important role of Ru playing in the stable immobilization of Au particles on the Ti substrate. The prepared nanoporous Au and Au-Ru electrocatalysts present novel morphological structures and significantly high electroactivity.