Synthesis of 0-D and 1-D Gold Nanomaterials and Properties of Gold Nanoparticles-deposited Mesoporous TiO2

• Main Authors: Chain-Fang Shieh, 謝倩芳
• Other Authors: Hong-Wen Wang
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/88453366014123411173

碩士 === 中原大學 === 化學研究所 === 94 === In this study, three subjects have been investigated：i.e. (1) the synthesis of gold nanoparticles from bluk gold by chemical solution process, (2) the synthesis of 1D gold nanorods/nanotubes via template growth and electrochemical deposition, and (3) the synthesis and photocatalytic properties of gold nanoparticles on the mesoporous TiO2 powders. First, gold nanoparticles with diameter less than 10 nm were prepared by different methods using gold (III) precursor which was formed from dissolving bulk gold in aqua regia solution. The synthesized gold nanoparticles using reducing agent sodium citrate dispersed stably and the particle size was the least, about 7~8 nm at pH=5 at a stabilizer/gold ratio of 2. In the synthesis of gold nanoparticle by surfactant (CTAB) method, the most stable Au suspensions were prepared but the morphology on the surface of the particles was bumpy. The gold nanoparticles using the reducing agent sodium borohydride could be formed at low temperature (about 0°C ~5°C) and particle size was less than 10 nm. Second, the synthesis of 1-D gold nanomaterials via template growth and electrochemical deposition using different concentrations of gold (III) precursor, deposition voltages, and deposition durations are carried out. Using a membrane with 100nm pore size, gold nanotubes are initially formed from the bottom and the wall of the pore channels. Preferred growing on the pore walls at low gold concentrations and low voltages is proposed to be responsible for the formation of nanotubes which are progressively thicker and sealed up into nanorods at longer durations. Optical property of the synthesized 1-D gold nanomaterials caused by the surface plasmon resonance of transverse (width) mode is identified using uv-visible spectrometry. And finally, the synthesis and photocatalytic property of gold nanoparticles on the TiO2 mesoporous nanopowders by chemical reduction process was studied. The commercial P25 TiO2 exhibits well crystalline anatase and rutile phases and better photocatalystic effect than that of pristine mesoporous TiO2. However, the residence of Au (III) ions on the surface of commercial TiO2 decreased its photocatalytic activity. The gold nanoparticles formed and resided in the pore of mesoporous TiO2 powders and greatly reduced the surface area of TiO2; however, enhanced the photocatalytic effect by prolonging the lifetime of photogenerated electron-hole pairs.