Preparation and characterization of (metal, nitrogen)-codoped TiO2 by TiCl4 sol-gel auto-igniting synthesis

The nitrogen-doped and (metal, nitrogen)-codoped TiO2 photocatalysts (metal = Ag, Ce, Fe, La) were synthesized by sol-gel auto-igniting synthesis (SAS) with the complex compound sol of TiCl4-NH4NO3-citri acid-metal nitrate-NH3·H2O as a precursor. The products were characterized by means of XRD, XPS, and UV-Vis diffuse reflectance spectra, and their photocatalytic activity was investigated under visible light. It was found that all the synthesized powders showed good absorption for visible light, and that the radius and alterable valence states of doping metallic cations played important roles on their photocatalytic activity. These results were discussed in detail.