EPR study of the illumination effect on properties of paramagnetic centers in nitrogen-doped TiO2 active in visible light photocatalysis

An electron paramagnetic resonance study of nitrogen-doped TiO2 samples has been carried out in the dark and under illumination with light at different wavelengths. N-center dot and NO center dot paramagnetic species were detected in the samples and their dynamics under illumination of TiO2 was investigated. Photosensitivity of the nitrogen-doped TiO2 and its photocatalytic activity under visible-light irradiation increases through the creation of additional levels in the band gap of TiO2 caused by doping.