Sol-gel Synthesis of Porous Crystalline TiO2–P2O5 Oxide with Thermal Stability

Porous TiO2–P2O5 oxide was synthesized by the sol-gel method in the presence of tri-block copolymer (EO)20(PO)70(EO)20 (Pluronic123) in queous solution. The TiO2 nanocrystals with anatase structure precipitated in the as-synthesized TiO2–P2O5 materials at 80°C, considerably lower than that for traditional heat treatment in the solid state, which maintained a stable size of 3.6–4 nm upon calcinations below 500°C. It is believed that P2O5 glass phase prevents the coarsening of TiO2 nanocrystals below 500°C. The mixed oxide exhibited a specific surface area of 170–200 m2/g after calcining in the temperature range of 300–500°C.