Mechanism of the formation of photosensitive nanostructured TiO2 with low content of CdS nanoparticles

Abstract

A method for synthesizing a CdS/TiO₂ composite material, active in the visible region, was described. The CdS/TiO₂ composite was obtained by the sol–gel synthesis of nanostructured TiO₂ in a medium of a stable colloidal solution of CdS nanoparticles. The TiO₂ matrix produced by the sol–gel process is amorphous and contains a nanocrystalline anatase phase, the content of which depends on the Ti(OBu)₄ hydrolysis rate. The content of CdS nanoparticles forming in the colloidal solution and participating in the TiO₂ matrix sensitization is determined by the initial CdS: Ti(OBu)₄ ratio. Although the content of CdS nanoparticles in the composite is low (no more than 3 wt %), the composite demonstrates catalytic activity in the visible region, thus proving the possibility of reducing the content of toxic CdS nanoparticles in the TiO₂ matrix without decreasing the photosensitivity of the CdS/TiO₂ composite.