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用透射电镜(TEM)技术研究了Pt/TiO_2催化剂的表面形貌。经高温下氢处理的Pt/TiO_2,表面上原来高分散的不规则的Pt微粒发生迁移并构成多边形粒子。暗场TEM照片上的“蝶”形图象说明多边构形实际是外延生长的Pt多面体微晶。确定了在氢气氛中加热是造成TiO_2半导体表面缺陷,并导致Pt粒子规整构形的重要条件。还发现Pt/TiO_2的表面微观形貌和催化性能之间有并行关系。用金属-半导体相互作用的观点可以合理地解释这些结果。
The surface morphology of Pt / TiO_2 catalyst was investigated by transmission electron microscopy (TEM). Hydrogen-treated Pt / TiO 2 at high temperature migrates irregularly-dispersed Pt particles on the surface and forms polygonal particles. The “butterfly” image on the dark field TEM image shows that the polygon is actually epitaxially grown Pt polyhedron crystallites. It is confirmed that heating in hydrogen atmosphere is an important condition for the surface defects of TiO 2 semiconductor and leads to the regular configuration of Pt particles. It is also found that there is a parallel relationship between the surface morphology and the catalytic performance of Pt / TiO 2. These results can be reasonably explained in terms of metal-semiconductor interaction.