Enhanced visible light photocatalytic activity by up-conversion phosphors modified N-doped TiO2

The development of photocatalytic processes is strongly related to an efficient irradiation of the catalyst surface. A chance to get a significant reactivity enhancement is the promotion of the photocatalyst with up-conversion phosphors able to convert low-energy into high-energy photons. In this work it was found that the photocatalytic activity of visible active N-doped TiO2 (NdT) can be strongly enhanced when it is promoted by the presence of organic up-conversion phosphors (OP) in the catalyst formulation. Such photocatalysts (NdT/OP) have been prepared and tested in the photocatalytic degradation of a wide range of organic dyes in the presence of visible light irradiation emitted by green or white LEDs. The photocatalytic activity of NdT/OP in the presence of green LEDs is attributed to the up-conversion property of OP phosphors that emit at 434 nm, wavelength suitable for photoexciting NdT. Moreover, NdT/OP showed a dramatic enhancement of photocatalytic activity when white LEDs were used as light source. In this case, the NdT supported on OP surface is excited both by the emission spectrum of the white LEDs and by the blue emission of the phosphors (OP), excited by the green component emitted by white LEDs. The obtained results make NdT/OP photocatalyst a very suitable system to achieve high photocatalytic activity with solar light. (C) 2015 Elsevier B.V. All rights reserved.