A simple route for the preparation of P-modified TiO2: Effect of phosphorus on thermal stability and photocatalytic activity

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, P-31 MAS NMR, FT-IR, and UV-vis methods). It was found that the phosphorus existed as amorphous titanium phosphate in TiO2 framework after calcination at temperature of 500-700 degrees 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 TiO2 increased dramatically from 8 to 59 nm when the temperature increased from 500 to 900 degrees C. This change was associated with the formation of pyrophosphate TiP2O7 species through condensation of the concentrated phosphate species. The BET surface area of modified samples was 3.4-fold higher than that of unmodified TiO2 and was 70% higher than that of commercial Degussa P-25. The photocatalytic activity of P-modified TiO2 was 1.5-fold higher than that of commercial Degussa P-25 and was 49% higher than that of unmodified TiO2 under UV irradiation. Phytotoxicity was assessed before and after irradiation against seed germination of tomato (Lycopersicon esculentum). (C) 2011 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.