Investigation of nitrogen doped and carbon species decorated TiO2 with enhanced visible light photocatalytic activity by using chitosan

Nitrogen-doped and carbon species decorated TiO 2 composites (Cts/TiO 2 ) are prepared by using chitosan as a natural nitrogen and carbon source to combine with TiO 2 by a facile and low-cost method for the first time. Their structures and properties are characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), N 2 adsorption–desorption isotherms (BET), and electron spin resonance spectroscopy (ESR). The results show that the visible light absorption range of the composites even can be extended to 650   nm. Photocatalytic degradation of Rhodamine B (RhB) under visible light (420   nm   <   λ   < 800   nm) irradiation is used as a model reaction to evaluate the photocatalytic activity of the composites. When the additive amount of chitosan is 0.25   g, the sample Cts/TiO 2 -25 possesses the highest activity, which is over 4.8 times of N-TiO 2 . The detection of active species during the photocatalytic process shows that superoxide radicals (O 2 − ) play the most important role, then the probable degradation mechanism of the photocatalysts is proposed simultaneously. It is hoped that our work will open a new doorway to use a simple and green method to get high-efficiency TiO 2 -based photocatalysts.