Study Of Synthesis Of Nano-sized Au And Its Electrocatalytic Properties

In recent years, the contradiction of traditional fossil fuels and environmental protection has become more and more acute. Hydrogen and fuel cells are being extensively investigated as an alternative to fossil fuels because of its environmentally green by-product. Water electrolysis is a simple, mature industrial method, for production of hydrogen. At the same time, fuel cells as power generation technology have been duly noted. In this paper, Au-based nallocatalysts were prepared for fuel cells and water electrolysis. And their electro catalytic activities have also been studied.The main contents are listed as follows:(1) Chemical reduction method was used to synthesis of a series of Au, and Au@Pd catalyst was prepared on this basis. XRD analysis shows that, Au@Pd only shows a characteristic peak of Au, indicating Pd deposited on the surface of Au amorphous is amorphous. By characterizing the spectrum of UV-visible, the diameter of four different sizes of Au are 66.76 nm、56.57 nm、41.43 nm and 31.13 nm. Au@Pd has excellent alcohol oxidation activity, the ethanol oxidation activity is 4.41 times than Pd, methanol oxidation activity is 3.8 times than Pd; and 2.20 times than AuPd alloy. The result indicated that Aured/C nanoparticles have minimum particle size. Electrochemically active area of Aured/C is 2.13 times larger than Aublack/C. In addition, Au@Pd/C oxidized small organic molecules to CO2 more completely than Pd/C.(2) Chemical reduction method was used to synthesis of a series of Au-Cu. The SEM characterization shows the morphology and particle size of Au-Cu in different molar ratios are similar. The catalysts were characterized X-ray diffraction. The diffraction peak of Au(111) move with different proportions of Au-Cu. Analyses of the data indicate the oxygen reduction reaction(ORR) on Au-Cu/C catalyst carried out with a four electron transfer process to form water while Au/C catalyst carried out with two and four mixed electron transfer mechanism. The moving of half-wave potential indicates that the Au-Cu complex electrode exhibits high ORR catalytic activity. Simultaneously, Au-Cu has good oxygen evolution activity(OER).The current density of Au-Cu for OER achieved 1.2677mA?cm-2 at potential of 0.826 V versus Hg/HgO reference electrode. The current density is2.29 times than Au/C. On this basis, we prepared Au3Cu@100MLPt/C catalyst. Its electro-catalytic performance for HER improved greatly in 0.5 mol?L-1 H2SO4.The current density of Au3Cu@100MLPt/C and Pt/C are very close in per unit apparent area. In per unit mass in Pt, the current density of Au3Cu@100MLPt/C is 2.88 times greater than Pt/C.In per unit electrochemical area, the current density of Au3Cu@100MLPt / C is 13.6 timesthan Pt/C. The hydrogen evolution activity and utilization of Pt improve greatly.(3) Thermal decomposition method has been utilized for anchoring Au-TiO2 binary alloys electrocatalytic materials. The morphology, structure and surface electronic structure of Au-TiO2 binary alloys electrocatalytic material is investigated and the effect of pyrolysis temperature and composition are analyzed. We can see form the SEM, the particle size of the formation of a binary alloy was significantly reduced and dispersed evenly. And in a certain range, the particle size is reduced with the increasing of temperature or the proportion of TiO2. Form the XRD analysis; we can see that in Au-TiO2 binary alloy, Au is in crystalline form while the crystalline of TiO2 is in a lower degree. The XPS characterization shows that the electronics between Au and Ti metastasis transfer obviously. The surface electron binding energy of Au is reduced. The electro catalytic activity for hydrogen evolution reaction(HER) is investigated. It shows us that the catalytic activity of Au increased significantly accompanying with TiO2. When hydrogen evolution current density is 3 mA?cm-2, Au-TiO2/CP and Pt/CP showed electro-oxidation of water at applied voltages of 124 mV and 200 mV vs. RHE,respectively. Further investigations into the stability of the Au-TiO2/CP also show a good performance.