Structural, morphological and photocatalytic properties of nanostructured TiO₂/AgI photocatalyst

Nanostructured TiO2/AgI photocatalyst under the action of ultraviolet or visible electromagnetic radiation effectively neutralizes organic pollutants in the aqueous environment. It is a nanostructure in which micro- and small mesopores of anatase TiO2 are filled with silver iodide in the superionic state. The content of the alpha-AgI ion-conducting phase in the volume of TiO2 pores can be similar to 20 wt %. To obtain a photocatalyst, titanium dioxide is synthesized by the sol-gel method, using a titanium aquacomplex solution [Ti(OH2)(6)](3+)center dot 3Cl(-) and a Na2CO3 modifier additive as a precursor. The modifying additive during synthesis ensures the fixation of =O2CO carbonate groups on the surface of oxide material particles. The presence of these groups leads to an increase in both the pore volume and the specific surface area of TiO2. The specific surface area of carbonized titanium dioxide is 368 m(2)center dot g(-1), the pore volume is 0.28 cm(3)center dot g(-1), and their size is 0.9-4.5 nm. To fill the micro- and small mesopores of TiO2 with the superionic alpha-AgI phase, Ag+ cations are first adsorbed from the AgNO3 solution on the titanium dioxide surface, and then the oxide material is contacted with the KI solution. Compared to the Evonik P25-TiO2 photocatalyst, the nanostructured TiO2/AgI photocatalyst demonstrates a significantly higher efficiency of photodegradation of organic dyes Congo Red and Methyl Orange in visible and ultraviolet radiation. The most active TiO2/40AgI sample achieved complete degradation of the CR dye (5 mg/L) in 6 minutes of UV irradiation (lambda = 365 nm), while the efficiency of commercial P25-TiO2 over the same time was only 42%.