Increasing the Photoactivity of N-doped TiO2 Photocatalysts Using Phosphors as Light Carriers

The aim of the work was to increase the photoactivity of N-doped TiO2 photocatalyst, active in visible light region, through the improving of the illumination efficiency. Microradiators like phosphors (namely, ZPS) which absorb an electromagnetic radiation by the external light source (UV) and, with no time delay, emit visible light, opportunely selected to be able to excite N-doped TiO2 photocatalyst. Preliminary investigations were performed on physical mixtures of phosphors and N-doped TiO2, evaluating the decolourization of methylene blue (MB). The simultaneous presence of N-doped TiO2 and light carriers showed an increased decolourization activity, reaching about 100 % with a total TOO removal after 3 h of irradiation. To get core-shell photocatalysts, N-doped TiO2 was supported on ZPS (NTiO2-ZPS) by a modified sot gel method. The content of N-doped TiO2 was varied in the range 5-50 wt % to find an optimum loading. The photocatalytic activity of NTiO2-ZPS was evaluated for the removal of MB under UV illumination. The performances of NTiO2-ZPS showed an improved efficiency in decolourization process of MB, equal to 100 % after 90 min of irradiation, with a total TOO removal. The influence of several parameters, such as dye type and concentration has been studied.