Preparation, Self-Assembly, And Properties Research Of Au Nanoparticles.

Au nanoparticles has a potential application in bio-sensor, catalysis, and optics field because of its unique optic and electric properties which closely depend on its size and shapes. TiO₂, as a semiconductor photocatalyst, was broadly concerned recently. The report indicates that the photo-induced activity may increase after Au particles deposition. In this paper, near-sphere shaped and non-sphere shaped Au nanoparticles were prepared. And self-assembly pattern was accquired. Comparison of photocatalysed degradation performance between TiO₂ and Au/TiO₂ photocatalysis system was also given.Size controlled Au nanoparticles have been produced by reduction of HAuCl4 using KBH4 as a reductant. After two-time filter, monodispersed Au nanoparticles with small size were obtained. The optimal amount of KBH4 added in was 0.4mL. The HR-TEM photo shows that Au nanoparticles is face centered cubic structure, and the crystal plane of Au nanoparticles is (100). After inorganic salt was excluded by using semipermeable membrane, self-assembly pattern was obtained on TEM grid. CTAB was employed as surfactant to prepare non-sphere shaped Au nanoparticles through seed mediate method. Cubic, rectangular, rod and tetrahedron shaped Au nanoparticles had been prepared with the size range from 200 to 1000nm. The principle indicates that with the reactant concentration increased, more rod shaped Au nanoparticles may be prepared, whereas more cubic and rectangular shaped Au nanoparticles could be obtained by decreacing the reactant concentration. The appearance of tetrahedron shaped Au nanoparticles maybe resulted from a high local concentration.TiO₂ membrane was prepared through sol-gel method, then was annealed in different temperatures. The morphology of the membrane was observed with porous structure by SEM. The XRD result suggests that the crystal style of TiO₂ membrane prepared is anatase. With anneal temperature increase, the size of TiO₂ particles within membrane increased, but the efficiency and rate of degradation process decreased. Better degraded effect could be obtained by employing H2O2 as catalysant meanwhile proper content of TiO₂ was also needed.Au nanoparticles could be deposited on membrane surface after TiO₂ membrane was prepared. Photocatalysed degradation experimentals were taken under the condition of different anneal temperatures and different catalysants. The result indicates that the size of TiO2 particles within membrane decrease after Au nanoparticles deposition. The efficiency and rate of degradation process also increased.