Visible photocatalysts based on nitrogen and carbon doped nanocrystalline titanium dioxide

Photocatalysts functioning in the visible spectrum range based on nanocrystalline titanium dioxide doped with nitrogen and carbon in the form of microspheres were obtained. Their structural, optoelectronic and photocatalytic properties were studied. The electron paramagnetic resonance method was used to identify spin centers (defects) and determine their concentrations in all the samples under study. Nitrogen atoms with an unpaired electron and Ti3+/oxygen vacancy centers were found in the microspheres doped with nitrogen. Dangling carbon bonds were recorded in the microspheres with carbon impurities. Photocatalysts doped simultaneously with nitrogen and carbon are characterized by both nitrogen and carbon spin centers. It was found that the concentration of defects increases during illumination, which is explained by their recharging. A correlation was established between the concentration of spin centers and the rate of photocatalysis in the obtained structures. It was shown that samples doped with two impurities are characterized by a high photocatalysis rate and prolonged catalysis for more than five hours after the illumination is turned off, as well as stable photocatalytic properties for several years, which determines the novelty of the studies and high prospects for use in ecology and biomedicine.