ИСТИНА

The most promising area of application titania is photocatalysis — chemical decomposition of organic impurities, including toxic, on the surface of titania. Note that the functional characteristics (photoactivity, reactivity, etc.) of titania are determined by its physicochemical properties. In recent years, photocatalytic heterostructures, formed by a large number of oxide-oxide nanoheterojunctions (one of which is nitrogen doped nanocrystalline titanium dioxide due to its high photoactivity) have been actively studied because of their ability to accumulate photoinduced charge carriers. We have studied the photoelectron properties of nanoheterojunctions of various oxides (N-TiO2/MoO3, N-TiO2/WO3, N-TiO2/V2O5, N-TiO2/MoO3/V2O5), arranged in the form of microspheres, obtained by the method of aerosol pyrolysis. We have used EPR and UV-Vis spectroscopy for the investigation of TiO2 based microspheres. It was established that the main type of radicals in the samples under study are Ti3+/ oxygen vacancies, N• radicals, Mo5+ and V4+ centers. Under illumination, the intensity of the EPR signal from all paramagnetic centers increased. After turning off the light, the complete relaxation of the EPR signal to its original state occurred during approximately the day for the microspheres N-TiO2/MoO3, N-TiO2/WO3, N-TiO2/V2O5 and for two days for the microspheres N-TiO2/MoO3/V2O5. This indicates the processes of separation and accumulation of charge carriers in the samples under study. The microspheres consisting of three metal oxides had the best oxidative activity and the most pronounced photocatalytic properties. Note that the photocatalysis takes place during 7-8 hours after turning off the illumination. The obtained results can be useful for development of energy efficient titania based photocatalysts.