Effect of SnO2 addition on phase transformation of TiO2 photocatalyst prepared by sol-gel method

The TiO 2 /SnO 2 composite nanocrystal with different mol ratios was prepared using the sol-gel technology and the effect of SnO 2 addition on the phase transformation of TiO 2 photocatalyst was discussed in the study as the crystal phase affects the photocatalysis greatly. The phase transformation process of pure TiO 2 and SnO 2 /TiO 2 composite powders were characterized by using X-ray diffraction, differential scanning calorimetry and thermo-gravimetry analysis. A small quantity of SnO 2 in the form of chloride accelerates the anatase-to-rutile transformation greatly. The substitution of larger-size tetravalent tin ion Sn 4+ for titanium ion Ti 4+ induces the lattice dilatation of titania crystal while the rutile-structured cassiterite plays as nucleating agent and facilitates the formation of rutile phase.