关于氧化锌—二氧化硅表面结构和表面酸性的补充研究

我们管报道浸渍法制备的ZnO/SiO_2的表面酸性和表面结构。证明:(1) ZnO单层分散在硅胶表面,分散阔值为～0.22gZnO/100m~2SiO_2;(2) 样品表面出现了单独的ZnO与SiO_2所没有的较强酸位并且其酸量与ZnO表面浓度有很好的对应关系。由此提出了ZnO与SiO_2表面相互作用形成了某种酸性结构单元的观点。Sumiyoshi,Tanabe等曾报道,用共沉淀法制取的ZnO-SiO_2表面酸性显著。认为酸性的根源是ZnO与SiO_2间形成了田部(K.Tanabe)模型所预示的那种二氧化物,结构中

A SUPPLEMENTARY STUDY ON SURFACE ACIDITY AND SURFACE STRUCTURE OF ZINC OXIDE-SILICON OXIDE

In this paper, the structure of ZnO-SiO_2 prepared by precipitation method has been studied by XRD, XPS and surface acidity measurement. The results show that ZnO is dispersed on the surface of SiO_2 as a monolayer and has its utmost dispersion capacity (threshold) for this series of samples as well as for the reported ZnO/SiO_2 which were prepared by impregnation. And there are some stronger surface bonding between ZnO and SiO_2 for these two series of samples. In the light of this view, the trend of chang of the density of surface acidic sites and the results of XRD for ZnO-SiO_2 reported by Sumiyoshi, Tanabe et al~2] can be also interpreted satisfactorily.In addition, authors proposed some comments on “the model structure of binary oxides” in the light of bond valence theory.