TiO2-CeO2nanometric powders prepared by sol-gel method

Nanometric powders in the TiO2-CeO2system were synthesized using sol-gel methods aiming at corrosion inhibitor preparation. The precursors employed were Ti(OiPr)4as TiO2source and Ce(NO3)3·6H2O or Ce(CH3CO2)3·xH2O as CeO2source. Several parameters were varied, like the cerium precursor (cerium nitrate or cerium acetate) and the TiO2:CeO2molar ratios. For both cerium sources binary powders with TiO2:CeO2= 4:1 or 1:1 molar ratios were prepared. The obtained materials were dried 12 h in an oven at 100 °C and then thermally treated for 1 h at 400 °C with a heating rate of 1 °C·min-1in order to eliminate the water and organic residues. In all cases, nanometric – predominantly amorphous – powders have been obtained which crystallized after the 1 h thermal treatment at 400 °C. The only exception was recorded for the TiO2:CeO2= 4:1 composition prepared from the Ce(NO3)3·6H2O precursor which remained amorphous after the thermal treatment. Even though the primary particle sizes were ~ 4-5 nm, the material is constituted from aggregates larger than 50 nm. The desired presence of cerium in two valence states, necessary in active corrosion protection, was achieved and it was put into evidence by XPS and DTA/TGA for the TiO2:CeO2= 4:1 binary compositions. Future studies have to be performed in order to reduce the agglomeration of the material.