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

Abstract

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 α-AgI ion-conducting phase in the volume of ТіО2 pores can be ~20 wt %. To obtain a photocatalyst, titanium dioxide is synthesized by the sol-gel method, using a titanium aquacomplex solution [Ti(OH2)6]3+•3Cl- and a Na2CО3 modifier additive as a precursor. The modifying additive during synthesis ensures the fixation of =О2СО 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 ТіО2. The specific surface area of carbonized titanium dioxide is 368 m2•g-1, the pore volume is 0.28 cm3•g-1, and their size is 0.9-4.5 nm. To fill the micro- and small mesopores of TiO2 with the superionic α-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 ТіО2/40AgI sample achieved complete degradation of the CR dye in 6 minutes of UV irradiation, while the efficiency of commercial Р25-TiO2 over the same time was only 42%.