A simple route for the preparation of P-modified TiO 2: Effect of phosphorus on thermal stability and photocatalytic activity

Abstract

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 59 nm 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).