Photocatalytic oxidation of ethanol vapors under visible light on CdS-TiO ₂ nanocatalyst

The preparation of multiphase CdS/TiO ₂ photocatalysts by the deposition of cadmium sulfide nanoparticles on the surface of commercial titania Hombifine N and Degussa P25 in the presence of a chelating agent (ammonia) was carried out. The photocatalysts were characterized by a wide range of experimental techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray (EDX) spectroscopy, X-ray fluorescence (XRF) spectroscopy, and UV/VIS spectroscopy. The photocatalytic activity was tested in the reaction of ethanol gas-phase oxidation under visible light irradiation (λ > 420 nm) in a batch reactor. The deposition of cadmium sulfide on the surface of anantase/rutile titania Degussa P25 was found to produce higher activity in comparison to the deposition on anatase Hombifine N. The good stability and activity of the multiphase system seem to be caused by the formation of hetero-junctions between CdS and TiO ₂ nanoparticles resulting in the efficient charge separation and decreased electron-hole recombination.