Synthesis of CdS/TiO₂ nanocomposites by using cadmium thiolate derivatives as unimolecular precursors

Abstract

Highly porous nanocrystalline films of TiO 2 sensitized with semiconductor nanocrystals (NCs) are very promising for photovoltaic applications, NCs being more versatile and efficient than organic dyes as sensitizer. In this framework, the visible light absorption of TiO 2 can be improved by the superposition of CdS NC absorption band, that is tunable between 2.5 and 5.2 eV. Here, we report on a novel in situ approach for the synthesis of CdS NCs in mesoporous sol-gel TiO 2 anatase films by using as starting reagent for CdS, [Cd(SBz) 2 ]MI, where MI represents 1-methylimidazole. The precursor has been adsorbed into the TiO 2 pores and then decomposed at 480 8C, the procedure being studied for TiO 2 films with different porosity. The matrices have been investigated by atomic force microscopy. X-ray diffraction measurements on TiO 2 matrix and on the corresponding CdS/TiO 2 nanocomposite material revealed a variation of the NCs size of both TiO 2 and CdS as a function of the matrix porosity. The optical properties of the TiO 2 and CdS/TiO 2 have been studied by UV-Vis transmission spectroscopy. CdS/TiO 2 nanocomposites, having higher absorption efficiency with respect to TiO 2 , are suitable as building blocks for 3rd generation solar cell design.

Unusual reactivity of visible-light-responsive AgBr–BiOBr heterojunction photocatalysts

“…It is worth noting that the absorption is not linearly varying to AgBr loadings. Their light absorption intensity in a broader region and the nonlinear change of absorption edges in the bandgap region deviate the mechanistic spectrum superposition principle [31,32]. A possible reason is that the UV-Vis DRS reveals surface absorption information, but only a small fraction of AgBr existing on the surfaces of the heterojunctions can be recorded in the UV-Vis DRS.…”

Double Effect Electron Transfer System in the AgBr/ZnO Composite with Enhanced Photocatalytic Degradation Performance against 3‐Chlorophenol under Visible Light Irradiation

“…Also, the absorption is not linearly changing with varying AgBr contents. In addition, the nonlinear variety of absorption peaks in the band gap region shifted the mechanistic spectrum superposition principle . AgBr/ZnO samples displayed catalytic activity than ZnO alone.…”

Highly Efficient Precursors for Direct Synthesis of Tailored CdS Nanocrystals in Organic Polymers

“…On the other hand, they protect inorganic NCs from aggregation, increase their solubility and miscibility, and preserve their chemical and physical properties as electrical and photoconductivity, nonlinear optical response, photoluminescence (PL), and electroluminescence . Finally, the combination of semiconductor NCs and inorganic semiconductor matrices, , or conjugated polymers, , with improved power conversion efficiency represents the newest and more interesting solution for high stability, low cost, and easy processing nanocomposite for radiation detection , and light emission devices , and for photovoltaic applications. ,, …”