Influence of manganese oxides on the optical absorption and photocatalytic activities of titanium dioxide

Nanocrystalline titanium-manganese mixed oxides (TMMO) with Mn content of 13–16 at. % were first synthesized by manganese hydroxide precipitation on anatase or rutile particles. UV-vis absorption spectra were investigated in 2.4–6.0 eV region and revealed that compared with pure TiO2 the presence of manganese oxides results in an increase of the absorption intensity and significant red shift of the TMMO absorption edge. Photocatalytic activity of pure TiO2, Mn²⁺ doped TiO2 and TMMO during the photocatalytic decomposition of the safranine dye under UV irradiation was studied. A great improvement of photocatalytic activity is registered for Mn²⁺-doped TiO2 (anatase and rutile), and rutile-based TMMO sample.