Sonochemical synthesis and visible light photocatalytic behavior of CdSe and CdSe/TiO2 nanoparticles

This paper reports an ultrasound-driven approach in the synthesis of CdSe and CdSe sensitized TiO2, and also the their photocataltyic behavior of these materials under visible light. The results show that the CdSe/TiO2, coupled system has a much higher photocatalytic activity than that of pure TiO2, and CdSe in the degradation of 4-chlorophenol under visible light irradiation. The CdSe nanoparticles which act as a photosensitizer not only extend the spectral response of TiO2, to the visible region but also reduce the charge recombination. Blue shift in the absorption onset confirms the size quantization of the CdSe nanoparticles under sonochemical synthesis. The quantum size effect alters the conduction and valence bands of CdSe particles to the appropriate energy levels in the coupled semiconductor system. This can make the electron injection from CdSe to TiO2, more efficient and increase the degree of charge separation significantly, thereby enhancing the performance of the new coupled photocatalyst system. (c) 2005 Elsevier B.V. All rights reserved.