Preparation and characterization of a nano-sized Mor Ti mixed photocatalyst

Nano-sized molybdenum-doped TiO2 MorTi.mixed oxide photocatalysts were prepared with the Mo5q content varying from 0 up to 2.5 mol%, to shift the absorption onset into the visible region and to enhance the efficiency of photocatalytic activity by retarding the ey–hq. recombination. Prepared MorTi mixed oxides were characterized by ultraviolet and visible spectroscopy UVrVIS., transmission electron microscopy–electron diffraction pattern TEM–EDP., X-ray diffraction XRD., energy dispersive X-ray EDAX.and X-ray photoelectron spectroscopy XPS.. Photonic efficiency was also investigated with the degradation rate of dichloroacetate DCA.and light intensity measured by actinometry. TEM–EDP and XRD patterns showed that particles were in the form of anatase with the diameter of ca. 4 nm. The appreciable red-shift in the UVrVIS absorption spectra was monitored at each preparation stage — aging and dialyzing. The red-shift varied with addition of Mo, in the case of 2.5% MorTi the UVrVIS absorption started at around 0.22 eV less than in nano-sized pure TiO2 about 3.42 eV.. EDAX verified that the amount of Mo in the prepared mixed oxides was as required, and XPS analysis revealed that Mo V. existed in the TiO2 lattice. The measured photonic efficiency increased to 0.28 with DCA at 0.5 mol% Mo, and then decreased as the Mo content increased above 0.5 mol% Mo. This could be explained in terms of the changing prevailing phenomena — electron trapping and recombination — as the amount of dopant increased in terms of the distance between the trapped sites of the charge carriers. q2000 Elsevier Science B.V. All rights reserved.