Structure of Vanadium Oxide Monolayers

Structure of Vanadium Oxide Monolayers. - Yoshida etal.12 conclude from e.s.r. spectra that on y-Al2 03 vanadium oxide is present as square-pyramidal V05-units, on Si02 as tetrahedral V04-units. Hanke et al.52 conclude from 

Khalif et al.141 conclude from measurements of the heat of adsorption of 02 and e.s.r. measurements that there is unactivated adsorption on vanadium ions with a low co-ordination number of 3 or 4, whereas activated adsorption is observed at higher temperatures on ions with square pyramidal coordination. 02 adsorption occurs only as O2- in (V=0) or (V—O—V) groups and not as radicals which, according to these authors, is different from the behaviour of catalysts obtained by impregnation. 

Akimoto et al 6 conclude from e.s.r. spectra that different forms ofV4+ ions are formed depending on the support. A reactive form, which is also preferentially formed in V205 is necessary for high selectivity in benzene oxidation. In well spread vanadium oxide on Al2 03 and MgO this is hardly formed in contrast to Si02 on which the dispersion is much less. 

Bond and Briickmann93 conclude that there are different surface phases of 

Roozeboom et a/.143 conclude from laser Raman spectroscopic results that the vanadium oxide monolayers consist of a mixture of octahedrally and tetrahedrally co-ordinated vanadium, the former being present in a polymeric network of distorted octahedra. 

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