Plasmonics and Photocatalysis of Sputtered Ag Nanoparticles Impregnated in N-TiO2 Thin Films

• Main Authors: Jheng-Long Huang, 黃正隆
• Other Authors: Ming-Show Wong
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/7wa4g7

碩士 === 國立東華大學 === 材料科學與工程學系 === 106 === In this study, reactive magnetron sputtering was used to prepare different nitrogen doped titanium dioxide film (N-TiO2), which was combined with silicon dioxide layers and Ag nanoparticles (Ag NPs) to form a sandwich multilayer structure. The surface plasmon effect of Ag NPs could enhance the absorption of visible light of the film, and might improve the photocatalytic properties of titanium dioxide. The structure and crystallinity of the films were analyzed by XRD. The elemental composition and bonding of the films were examined by XPS. UV-vis spectrotometer was used to study the absorption phenomena of the films. The photocatalytic efficiency properties of the films under visible-light illumination were evaluated by measuring the decomposition rate of methylene blue in aqueous solution. From the experimental results, with the increase of silver sputtering time, the content and the size of silver nanoparticles increased which resulted in enhancement of visible light absorption of the films, but the rate of increase is limited. The silver nanoparticles may combine with the oxygen in the air or with the oxygen of TiO2 films and get oxidized, which reduce the surface plasmon effect of the nano-silver and as a result decrease the visible light absorption of the film. For this reason, SiO2 layers were deposited above and below silver layer to protect from oxidizing. At 30 seconds (Ag30-NT) deposition time of Ag, the distribution of Ag nano-particle size is uniform, so we used this parameter to deposit N-TiO2/SiO2/Ag/SiO2/N-TiO2 multilayer. This structure can provide Ag NPs with good surface plasmon effect and enhance the absorbance of the films in the visible light. However, the film didn’t show significant photocatalytic property. The possible reason is that SiO2 layer is too thick, which makes electron and hole pairs of the film hard to reach the surface of the film and could not exhibit significant photocatalytic property. When the nitrogen flow rate is 20 sccm, N-TiO2 has 16.9 at% of nitrogen content. The phases of the film obtained were anatase, Ti3O5 and TiN. The absorption in the visible light of 20 sccm nitrogen doped with TiO2 (N20T) is 3-4 times higher than TiO2 film. In addition, depositing anatase TiO2 on sample N20T, improved the photocatalytic phenomenon about 80% compared to that of pure TiO2 films. So the catalytic properties of photocatalyst films were affected by the absorbance and surface properties of the films.