Nanosize Ti-W mixed oxides:: Effect of doping level in the photocatalytic degradation of toluene using sunlight-type excitation

In this report we investigate the behavior of nanosize Ti-W mixed oxides with anatase structure in the photoelimination of toluene using sunlight-type excitation. These systems were prepared by a microemulsion method and their physicochemical properties characterized by a multitechnique approach using X-ray diffraction and photoelectron spectroscopy, as well as Raman, infrared and UV-vis spectroscopies. The preparation method allows the incorporation of up to ca. 20 at.% of W in substitutional positions of the anatase network. The photoactivity of the substitutionally disordered Ti-W mixed oxides grows in parallel with the W content of the material and improves the performance of a single anatase sample prepared in a similar way and also that of the Degussa P25 material. The chemical/physical basis of such behavior is discussed in light of the characterization results. (C) 2002 Elsevier Science (USA).