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A new approach to hydrogen production from water is described. This simple method is based on carbon dioxide-mediated water decomposition under UV radiation. The water contained dissolved sodium hydroxide, and the solution was saturated with gaseous carbon dioxide. During saturation, the pH decreased from about 11.5 to 7-8. The formed bicarbonate and carbonate ions acted as scavengers for hydroxyl radicals, preventing the recombination of hydroxyl and hydrogen radicals and prioritizing hydrogen gas formation. In the presented method, not yet reported in the literature, hydrogen production is combined with carbon dioxide. For the best system with alkaline water (0.2 m NaOH) saturated with CO

The paper deals with preparation of nanocrystalline zinc oxide doped with iron oxide obtained via calcination process. A mixture of iron and zinc hydroxides of various compositions was used as precursors of nanopowders. The samples were prepared by wet chemistry method – precipitation from the corresponding metals' nitrates' solutions using ammonia. The obtained hydroxides were filtered, dried and calcined at 573 K for 1 hour. A series of samples containing 5 to 95 wt.% of Fe2O3 was obtained. The phase composition of the samples was determined using XRD. Depending on the chemical composition the phases of hexagonal ZnO, and/or romboedric Fe2O3 and/or cubic ZnFe2O4 were identified. The mean crystallite size of ZnFe2O4 phase present in all the samples, determined using Scherrer's formula, varied from 8 to 12 nm. The morphology of the samples was investigated using SEM and HRTEM. X-ray photoelectron spectra of all the samples were analysed. A detailed spectroscopic and morphological analysis of the samples suggests a core-shell structure of the produced grains. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)