Synthesis and optic properties of titanium dioxide nanostructures doped with alkali metals

Resumo

The synthesis of nanotubes and faceted nanocrystals of titanium dioxide doped with alkali metals cations has been performed. It has been established that TiO₂ nanotubes with lengths of up to 100 nm and thicknesses of 50–500 nm obtained by solvothermal synthesis have an anatase structure in the direction of crystal growth. Faceted TiO₂ particles with sizes of 80–150 nm doped with Na and K cations (2–7 at % calculated to a yield of TiO₂ yield) preserve the anatase structure, whereas doping with Li induces the formation of a mixture of anatase and rutile. An analysis of the diffuse reflectance spectra showed that dopants had an insignificant effect on optic properties of TiO₂ nanoparticles. The high activity of these catalysts is explained by a decrease in the rate of recombination of charge carriers, rather than by the increase of their photo-generation yield.