Nanoporous CdS nanostructures, including nanosheets and hollow nanorods, have been prepared by a two-step aqueous route, which consists of a first precipitation of nanoporous Cd(OH) 2 intermediates and a subsequent S 2-/OHion-exchange conversion of the obtained Cd(OH) 2 used as template either to nanoporous CdS nanosheets with sizes up to 60 nm and an average thickness of about 9 nm or to CdS hollow nanorods with lengths up to 30 nm and outer diameters in the range 7-14 nm. The obtained CdS nanostructures containing nanopores with diameters of ∼3 nm exhibit a very large BET surface area of about 112.8 m 2 g -1 . A very high hydrogen yield of about 4.1 mmol h -1 under visible light irradiation (λ g 420 nm), corresponding to the highest apparent quantum yield of about 60.34% measured at 420 nm so far reported, has been attained over the obtained nanoporous CdS nanostructures loaded with monodisperse 3-5 nm Pt nanocrystals, which is due to an efficient charge separation, a fast transport of the photogenerated carriers, and a fast photochemical reaction at the CdS/electrolyte interface. The photocatalytic reaction conditions, such as the Pt-loading content, the amount of catalyst, and the concentration of sacrificial regents, have been optimized.

Monodisperse ternary ferrite (MFe2O4, M = Co, Ni, Mn, and Fe) nanocrystals have been synthesized through a facile and general route involving thermolysis of an intimately mixed binary metal−oleate complex with similar decomposition temperature of the constituents.

We describe a simple cadmium-thiourea complex thermolysis route for the formation of CdS nanocrystals with controlled dispersity, crystalline phase, composition, average grain size, and band gap. Visible-lightdriven photocatalytic activities for hydrogen production over the different CdS products have been compared. Phase structure and composition of the obtained CdS nanocrystals has been optimized either by changing the ratio of thiourea to Cd or by changing the annealing temperature. Over a broad annealing temperature range of 150-500 °C, either cubic, a mixture of cubic and hexagonal, or hexagonal CdS nanocrystals are obtained at thiourea/Cd molar ratios of <1.0, 1.5-2.5, and 3.0-4.5, respectively. Nanocrystalline cubic CdS is stable at temperatures as high as 500 °C for 0.5 h, and is converted to hexagonal CdS for annealing time longer than 1 h. The phase transition from cubic to hexagonal CdS occurs at temperatures of 200-300 °C, and pure hexagonal CdS is formed at annealing temperatures higher than 600 °C. The dispersity, crystallinity, and average grain size of the CdS nanocrystals has been determined as a function of annealing temperature and time. Increased photocatalytic activity is observed from the mixture of cubic and hexagonal CdS as compared to pure cubic or hexagonal CdS. Nearly monodisperse hexagonal CdS with good crystallinity and very fine particle size is expected to offer the highest photocatalytic activity for hydrogen production under visible light.