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

Abstract

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 TOC removal after 3 h of irradiation. To get core-shell photocatalysts, N-doped TiO₂ was supported on ZPS (NTiO₂-ZPS) by a modified sol–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 TOC removal. The influence of several parameters, such as dye type and concentration has been studied.