ELECTROCATALYTICALLY RELEVANT SURFACE-PROPERTIES OF ANODIC OXIDES - TIO2

Photoelectrochemical, electrochemical, surface structural and compositional studies of Ti parallel-to TiO2 and RuO2 parallel-to TiO2 interface are described. Anodic TiO2 films formed on Ti substrate revealed the presence of rutile as the only identifiable phase. A kind of epitaxial relationship between the titanium substrate and slowly grown TiO2 films was established. Thermally applied RuO2 on the anodic films acted as a probe for the microstructure of TiO2. RuO2 exhibited electrocatalytic and photoelectrochemical effect on slowly grown oxide films and showed none on step grown films. XPS and LEED studies of single crystal RuO2 and RuO2 parallel-to Ti interface showed that vapor deposited titanium reduces the always present RuO3 on the surface layers of RuO2. The pseudomorphism of rutile RuO2 and TiO2 yielded eventually to an epitaxial ordering of TiO2 overlayer. The structures of the order TiO2 overlayers at the (100) versus the (110) face of RuO2 were interpreted by the difference in their atomic arrangement.