Metal ion dopants

Studies have demonstrated that rare-earth ion modification can greatly improve the photocatalytic activity of Ti02 [147], although recent data disclosed uncertain doping effects (even controversial results) about transition metal ion dopants [140],... 

Choi, W., Termin, A., Hoffmann, M. 1994. The role of metal ion dopants in quantum-sized TiOj. J Phys Chem 98 13669-13679. 

As shown in reactions (6.5.13) and (6.5.14), metal ion dopants influence the photoreactivity of metal oxides by acting as electron (or hole) traps thereby altering the e /h -pair recombination rate. The energy level of should be less negative than that of the... 

Ballarini et al. (8) posed the question of whether vanadium phosphate catalysts for n-butane oxidation offer the scope for further improvements. They concluded that as a consequence of the complexity of the dynamic surface species present on the catalyst, optimization of such material will not be forthcoming without further fundamental investigations. Previous investigations have involved probing of a number of catalyst parameters, including the V P ratio, the content of metal ion dopants, and the method of preparation. These and related topics are evaluated in detail below. 

Sensitizing agents The sensitizing effect of metal ion dopants observed in initial studies by Ikeya et al. of certain inorganic substances does not seem to have been further explored. Attempts to increase the dose response of the alanine dosimeter by similar treatments have also not been entirely successful. An increase in the sensitivity of some of the new materials by transition metal ion dopants has, however, been reported [57]. An increase in the free radical yield by up to a factor two and a shortening of the relaxation times contributed to the increase in sensitivity. Those studies are still on an experimental level. 

The controlled incorporation of dopants is another important direction for further improvement in anodized materials. Suitable methods may include direct incorporation of a metal ion dopant during preparation of the metal film or by incorporation of anions from the electrolyte during anodization. 

W. Choi, A. Termin, M.R. Hoffmann, The Role of Metal Ion Dopants in Quantum-Sized Ti02 Correlation between Photoreactivity and Charge Carrier Recombination Dynamics. J. Phys. Chem. 98 (1994) 13669. 

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