A novel colloidal approach toward semiconductor/metal nanocomposites is presented. Organic-soluble anatase TiO(2) nanorods are used for the first time to stabilize Ag nanoparticles in optically clear nonpolar solutions in the absence of specific ligands for silver. Metallic silver is generated upon UV illumination of deaerated TiO(2) solutions containing AgNO(3). The Ag nanoparticles can be obtained in different size-morphological regimes as a function of the irradiation time, due to light-induced photofragmentation and ripening processes. A mechanism for the colloidal stabilization of the silver nanoparticles is tentatively suggested, which regards the TiO(2) nanorods as inorganic stabilizers, thus acting in the same manner as conventional surfactant molecules. The proposed photocatalytic approach offers a convenient method for producing TiO(2)/Ag nanocomposite systems with a certain control over the metal particle size without the use of surfactants and/or additives. Stable colloidal TiO(2)-nanorod-stabilized Ag nanoparticles can be potentially available for a number of applications that require "clean" metal surfaces, such as homogeneous organic catalysis, photocatalysis, and sensing devices.

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The photocatalytic performance of anatase TiO 2 nanorod-stabilized Ag nanoparticles has been investigated during the reductive bleaching of a model dye, Uniblue A (UBA), in homogeneous organic solutions. The activity of the TiO 2 /Ag nanocomposite has been found to vary continuously during the course of photocatalysis, following a concomitant light-induced modification of the metal nanoparticle size and size distribution. The direct involvement of the metal particles in mediating electron transfer between photoexcited TiO 2 and the target UBA is explained on the basis of the size-dependent redox properties of the metal nanoparticles. The present results can be useful in the design of new composite materials with well-tailored photocatalytic properties and long-term stability.

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The spatial evolution of compositions and sub‐structures inside focused‐electron‐beam‐deposited tips from dicobalt‐octacarbonyl Co2(CO)8 precursor at 25 keV and varying beam current (20 pA – 3 μA) is extensively studied for the first time by means of energy dispersive X‐ray spectroscopy, transmission electron microscopy, back‐scattered electron imaging, and ion‐induced secondary electron imaging. Transverse and longitudinal tip cross sections and lamellae were prepared by focused ion beam milling. Two sub‐structure types can be distinguished: a nano‐composite sub‐structure is grown during the initial deposition stage (small‐aspect‐ratio tips). It consists of cobalt nano‐crystals embedded in a carbonaceous matrix. A second distinct cobalt‐grain‐rich sub‐structure develops in high‐aspect ratio tips. Both sub‐structures vary in appearance and composition with increasing beam current: the initial nano‐composite sub‐structure increases in cobalt content and nano‐crystal size, and the cobalt‐grain sub‐structure develops polycrystal‐, texture‐, whisker‐, or platelet‐like habits. The directed precursor flux from a micro‐tube prevents a radial symmetry of the sub‐structures with respect to the impinging focused electron beam, at medium to high beam current. Homogeneous nano‐composite high‐resolution tips with small diameter and length were obtained at low beam current. Observations suggest an additional contribution to pure electron induced precursor molecule decomposition. The influence of electron beam heating and related chemical reactions is discussed.