A synthesis of highly dispersed nanocrystalline materials based on titanium dioxide in aqueous media at
neutral pH has been developed. The surface modification of TiO2 with tiron, ascorbic acid and rutin afforded
colored, transparent, colloidal solutions. Stability of yellow-orange colloids at pH = 7 has been
achieved. Photoactivity of materials has been assessed by photocurrent measurements. For all modified
materials visible light induced photocurrents have been recorded. The photocurrents were significantly
amplified in the presence of dissolved oxygen due to O2 reduction to superoxide. The studied materials
have been used to prepare thin films on glass substrates applying spin coating technique. Fabrication of
visible light responsive thin films, well bound to the substrate, involves synthesis of films of unmodified
TiO2, followed by their sintering and impregnation with the solutions of modifiers. SEM images showed
the formation of compact layers of titanium dioxide with particles of diameter within 15–30 nm. The
photocatalytic activity of synthesized films has been demonstrated in the reaction of terephthalic acid
oxidation to 2-hydroxyterephthalic acid, proving photogeneration of hydroxyl radicals upon visible light
irradiation (k > 400 nm).