from first principles PP-I-1

OP-V-4Design of the Nanocrystalline CdS/TiO 2 PhotocatalystKozlova E.A. 1 , Kozhevnikova N.S. 2 , Lemke A.A. 2 , Cherepanova S.V. 1 , Lyubina T.P. 1 ,Gerasimov E.Yu. 1 , Tsybulya S.V. 1 , Shchipunov Yu.A. 3 , Remplel A.A. 21 Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia2 Institute of Solid State Chemistry UB RAS, Yekaterinburg, Russia3 Institute of Chemistry FEB RAS, Vladivostok, Russiakozlova@catalysis.ruPurification of air from organic pollutants is currently an acute problem. Photocatalysis onsemiconductors is widely used as a purification method. The photocatalytic air treatmentmethod involves, in most cases, oxidation on titania (TiO 2 ) under UV irradiation. The majordrawback of TiO 2 is its rather wide band gap and, as a result, low photoactivity undersunlight, in which wavelengths shorter than 365 nm account for only a few percent.Therefore, to enhance the catalytic process efficiency, it is necessary to shift the absorptionband of the TiO 2 toward longer wavelengths. In this context, the present work has been aimedat designing a complex catalyst with the use of semiconducting cadmium sulfide.The narrow band gap CdS semiconductor is applied to the wide band gap TiO 2 , and this leadsto the extension of the light sensitivity range of the photocatalyst from 365 to 515 nm.Catalysts active under visible light on the basis of the composite of cadmium sulfide andtitania CdS/TiO 2 were obtained in an aqueous medium by a two-stage process. The first stagewas the synthesis of nanocrystalline CdS particles by chemical deposition from aqueoussolutions in the presence of the complexation agents, and the second stage was the depositionof CdS on a commercially available TiO 2 powder Hombifine N and Degussa P25.The CdS/TiO 2 catalyst activity was studied for the oxidation of ethanol to acetaldehyde in abatch system under visible light irradiation (λ > 400 nm). The catalytic activity of theCdS/TiO 2 Degussa P25, 0.34 μmol acetaldehyde per hour, turned out to be close to the valuesfor the CdS/TiO 2 Hombifine N. The activity of CdS/TiO 2 Hombifine N without adding acomplexation agent was 0.10 μmol acetaldehyde per hour, which is considerably lower thanthe activity of all systems containing complexation agents. The highest activity was exhibitedby the samples obtained from solutions of ammine and citrate cadmium complexes where thecomplex ion formation constants were minimal but sufficient to prevent the formation ofcadmium oxygenous impurities.Authors acknowledge SB RAS (project #35), UB RAS (12-C-3-1002) and FEB RAS(12-II-0-04-009) for financial support.86