- 作者: 簡淑華 ; 魏易文 ; 林茂成
- 作者服務機構: 中央研究院化學研究所
- 中文摘要: Irradiations of Ni/TiO/sub 2/ catalyst by UV in hydrogen at 77K produced not only Ni/sup +/ ions on the catalyst surface, but also Ni/sup 3+/ and Ti/sup 3+/ species in bulk or near the interface between nickel and titania. These photogenerated species were detected and characterized by low temperature electron paramagnetic resonance (EPR) spectroscopy. Relative spin concentrations of the photogenerated paramagnetic species (Ni/sup n+/ and Ti/sup 3+/) varied with the nickel content in titania. A high nickel content in the sample resulted in a high peak intensity ratio of Ni/sup n+/ to Ti/sup 3+/. It was found that the photoinduced self-redox reaction of Ni/sup 2+/ ions to form Ni/sup +/ and Ni/sup 3+/ ions has a priority over the photoreduction of Ti/sup 4+/ to Ti/sup 3+/ ions. The characteristic EPR spectrum of the Ni/sup 3+/ (3d/sup 7/) ions with g/sub 1/=2.268, g/sub 2/=2.237, and g/sub 3/=2.045 indicates that the Ni/sup 3+/ ions are most likely located in the substitutional sites of TiO/sub 2/, possibly near the surface rutile phase. The Ni/sup +/ species (3d/sub 9/) with g/sub □/=2.130 and g/sub .perp./=2.063 are on the surface of TiO/sub 2/. Both Ni/sup +/ and Ni/sup 3+/ ions are quite stable in hydrogen. The Ni/sup 3+/ ions seem to be responsible for anchoring the nickel ions onto titania and stabilizing the Ni/sup +/ species on the surface. The Ni/sup +/ ions are thus free from oxygen poisoning and still show a high activity toward olefin oligomerization.
- 英文摘要: --
- 中文關鍵字: Epr Spectra; Nickel; Titanium Dioxide; Photoreduction; Catalyst
- 英文關鍵字: 電子順磁共振光譜;鎳;二氧化鈦;光還原反應;觸媒