碩士 / 國立臺灣科技大學 / 化學工程系 / 96 / The goal of this study is to synthesize K4Nb6O17 photocatalysts with a preferred plane by the sol-gel method and to discuss the effect of the preferred plane and the structure of material on the catalytic efficiency of K4Nb6O17 towards water splitting reaction. The synthesized materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible diffusion reflection and Raman measurements and correspondingly carried out simulations for better understanding of the photocatalytic properties.
It was found that the synthesized the hydrated K4Nb6O17 shows orthorhombic structure. The particle size and the band gap are 1-2 μm and 3.6 eV, respectively. These results are integrated with simulation model to get (0 4 0), (2 3 1) and (0 12 1) planes. The (0 4 0) plane appeared to be less active towards hydroxyl adsorption due to the absence of any cations on the plane. There have niobium cation and potassium cation on (2 3 1) and (0 12 1) planes. It will makes the hydroxyl adsorbed on the niobium cation ,and improve the rate of H2 evolution. From the results of H2 evolution, it appeared that the (0 4 0) is independent of activity. The XRD peak ratio of (0 12 1) to (2 3 1) is proportionate to the rate of H2 evolution. In the Raman spectrum of the photocatalyst, the band appeared at 950 cm-1 is indicative of highly distorted area of the NbO6 octahedral. The distorted orientation in NbO6 structure may cause by the intercalation of the water of crystallization and shows the intensity of 950 cm-1 band. Due to the intercalation of the crystallized water in the interior layer, the distance of interior layer may increase and increases the reaction site of the edge of the catalyst. Interestingly the result obtained from the simulation is matched well with the Raman spectra. Thus, the intensity of 950 cm-1 band is also proportionate to the rate of H2 evolution.
| Identifer | oai:union.ndltd.org:TW/096NTUS5063093 |
| Date | January 2008 |
| Creators | Chang-chuan Lee, 李振銓 |
| Contributors | Bing-Joe Hwang, 黃炳照 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 102 |
Page generated in 0.0089 seconds