EXAFS study and photocatalytic properties of un-doped and iron-doped ZrO2-TiO2 (photo-) catalysts

The local zirconium and iron arrangements of the iron-doped ZrO2-TiO2 system, prepared by sol–gel impregnation method, were studied by EXAFS spectroscopy. Only a tetragonal ZrO2 structure is located on TiO2 surface. For the iron-doped ZrO2-TiO2 system, the presence of the Fe-O-Fe species as well as and Fe-O-Zr species located on the surface/pre-surface region are shown; it seems that iron is heterogeneously distributed, forming small iron oxide nanoclusters and Fex/ZrO2 (tetragonal) spots at the catalyst surface. The photocatalytic activity of the un-doped and iron-doped binary system ZrO2-TiO2 was investigated in two kind of photoreactions: the salicylic acid photooxidation and the photocatalytic reduction of Cr(VI). Different photocatalytic behaviour has been found for the un-doped and iron-doped ZrO2-TiO2 systems which have been explained in terms of the EXAFS study. This study represents an example of attempt to prepare a new potential photoactive mixed oxide system, containing two ions (Ti4+ and Zr4+) with good photocatalytic activity if it is compared with commercial TiO2 (Degusssa P25) calcined at 600 °C.