A comparative study of nanometer sized Fe(III)-doped TiO2 photocatalysts:: synthesis, characterization and activity

Fe(III)-doped TiO2 nanoparticles have been prepared in three different ways using inorganic or organic precursors, respectively. Transmission electron microscopic (TEM) structure characterization of the obtained particles reveals that TiO2 particles with and without the Fe(III) dopant possess the crystal structure of anatase. Cryo-TEM of vitrified samples confirms earlier assumptions that TiO2 nanoparticles tend to form three-dimensional networks in solution. A novel energy transfer mechanism is suggested employing these three-dimensional networks as antenna systems which lead to improved photocatalytic activities of the colloidal preparations. The performance of the nanostructured TiO2 with and without Fe-dopant for the photocatalytic oxidation of methanol producing HCHO is strongly dependent on the preparations and the Fe-content. Fe(III)-doped TiO2 nanoparticles prepared from organic precursors by the novel method (less than or equal to 2.5 atom% Fe) exhibit a greatly enhanced photocatalytic activity (quantum yield of HCHO up to ca. 15%).