A simple route for the preparation of P-modified TiO 2: Effect of phosphorus on thermal stability and photocatalytic activity
Résumé
Phosphorus-modified dioxide nanoparticles were prepared by sol-gel method. The effect of phosphorus precursor and calcination temperatures on phase transformation, grain growth and surface area were investigated using various spectroscopic and basic techniques (ICP-AES, XRD, BET, 31P MAS NMR, FT-IR, and UV-vis methods). It was found that the phosphorus existed as amorphous titanium phosphate in TiO 2 framework after calcination at temperature of 500-700°C. As results, slows down the particle growth of anatase and increases the anatase-to-rutile phase transformation. The average crystallite size of P-modified TiO 2 increased dramatically from 8 to 59nm when the temperature increased from 500 to 900°C. This change was associated with the formation of pyrophosphate TiP 2O 7 species through condensation of the concentrated phosphate species. The BET surface area of modified samples was 3.4-fold higher than that of unmodified TiO 2 and was 70% higher than that of commercial Degussa P-25. The photocatalytic activity of P-modified TiO 2 was 1.5-fold higher than that of commercial Degussa P-25 and was 49% higher than that of unmodified TiO 2 under UV irradiation. Phytotoxicity was assessed before and after irradiation against seed germination of tomato (Lycopersicon esculentum).