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建立了一种制备负载型模型催化剂的共溅射薄膜法。用TEM和HEED考察了用此法制备的Pt-TiO_2,Pt-Ti_2O_3和Pt-TiO薄膜模型催化剂经不同温度和气氛处理后的形貌和结构变化,并以纯Pt溅射薄膜样品作为对照。TEM结果表明,在这种铂-氧化钛模型催化剂中,Pt具有很高的分散度和良好的抗烧结性。根据由HEED测定的Pt的晶面间距d值随不同预处理条件而变化的规律,发现氢处理可引起Pt晶格膨胀,认为这是氢扩散进入Pt晶格的证据。观察到不同条件预处理引起的晶格畸变规律与纯Pt样品有明显差别,表明畸变机理不同。这被认为是部分还原的TiO_x(x<2)与Pt之间发生了较强的相互作用而扩散进入Pt体相,并可能与Pt形成类金属间化合物所引起,这将显著改变Pt表面的物化性质,而与铂-氧化钛体系的SMSI状态有密切的关系。
A co-sputtering thin film method was developed to prepare a supported catalyst. The morphology and structure of Pt-TiO_2, Pt-Ti_2O_3 and Pt-TiO thin film catalysts prepared by this method were investigated by TEM and HEED at different temperatures and atmospheres. Pure Pt sputtered film samples were used as a control. TEM results show that, in this platinum-titanium oxide model catalyst, Pt has a high degree of dispersion and good sinterability. According to the change of d value of interplanar spacing of Pt determined by HEED with different preconditioning conditions, it was found that hydrogen treatment caused Pt lattice expansion, which is believed to be evidence of hydrogen diffusion into the Pt lattice. It is observed that the lattice distortion caused by pretreatment under different conditions is obviously different from that of pure Pt sample, indicating that the mechanism of distortion is different. This is believed to be due to the strong interaction between the partially reduced TiOx (x <2) and Pt that diffuses into the Pt bulk and may form an intermetallic compound with Pt, which will significantly alter the surface of Pt Physicochemical properties, but with the platinum - titanium oxide system SMSI state is closely related.