ИСТИНА

In recent years the use of semiconductor nanomaterials in different purification systems is under a great interest. Titanium dioxide (TiO2) is one of such promising materials. In this work the nature of paramagnetic centers was identified and photocatalytic properties were investigated in nanocrystalline N-doped TiO2 (N-TiO2) and C-doped TiO2 (C-TiO2) obtained by sol-gel method. We have used the EPR technique for our investigations because it is sensitive to the detection of radicals and reactions between them. Photocatalytic properties were observed using the method of IR spectroscopy. The measurements of EPR spectra were performed at two temperatures: 295°K and 110°K. The samples were illuminated in situ with a lamp. All samples under investigation showed similar forms of signals with different intensities. The parameters of the simulated signals were the same as in the literature, so it was defined that NO● radicals in N-TiO2 samples and CO2– and OH● radicals in C-TiO2 samples were generated. To clarify the roles of the different paramagnetic centers in the photocatalytic decomposition of organic compounds the example of formaldehyde was used. The sharp decrease in the intensity of the EPR signal in the process of photocatalysis with doped TiO2 is correlated with a decrease in the amount of toxic contaminants in the air. Such correlation is a presentation of radical mechanism in material which can be used as a photocatalyst. This data was prepared by recording the change in intensity of the absorption bands of formaldehyde during period of time using an IR spectrometer. The obtained results can be useful for photocatalytic applications in purification systems. The experiments were performed using the facilities of the Collective Usage Center at Moscow State University.