Radiolytic synthesis

Actually, the kinetics study of the redox potential of transient clusters (Section 20.3.2) has shown that beyond the critical nuclearity, they receive electrons without delay from an electron donor already present. The critical nuclearity depends on the donor potential and then the autocatalytic growth does not stop until the metal ions or the electron donor are not exhausted (Fig. 8c). An extreme case of the size development occurs, despite the presence of the polymer, when the nucleation induced by radiolytic reduction is followed by a chemical reduction. The donor D does not create new nuclei but allows the supercritical clusters to develop. This process may be used to select the cluster final size by the choice of the radiolytic/chemical reduction ratio. But it also occurs spontaneously any time when even a mild reducing agent is present during the radiolytic synthesis. The specificity of this method is to combine the ion reduction successively ... 

The radiolytic synthesis consists of (1) either preparing first nanometric metal clusters in solution, which are then put in contact with the support (possibly by filtration), or (2) irradiating in situ the ionic precursors after their adsorption onto the supporting material. 

One of the important applications of mono- and multimetallic clusters is to be used as catalysts [186]. Their catalytic properties depend on the nature of metal atoms accessible to the reactants at the surface. The possible control through the radiolytic synthesis of the alloying of various metals, all present at the surface, is therefore particularly important for the catalysis of multistep reactions. The role of the size is twofold. It governs the kinetics by the number of active sites, which increase with the specific area. However, the most crucial role is played by the cluster potential, which depends on the nuclearity and controls the thermodynamics, possibly with a threshold. For example, in the catalysis of electron transfer (Fig. 14), the cluster is able to efficiently relay electrons from a donor to an acceptor, provided the potential value is intermediate between those of the reactants [49]. Below or above these two thresholds, the transfer to or from the cluster, respectively, is thermodynamically inhibited and the cluster is unable to act as a relay. The optimum range is adjustable by the size [63]. 

The chemical methods for the preparation of nanomaterial could be categorized as either template-directed or template-free. The template synthesis methods commonly used for the production of one-dimensional nanostructured PANI are further subdivided into hard template (physical template) synthesis and soft template (chemical template) synthesis approach according to the solubility of the templates in the reaction media. Non-template routes for the synthesis of one-dimensional nanostructured PANI such as rapid-mixing reaction method, radiolytic synthesis, interfacial polymerization, and sonochemical synthesis have also been reported [56], Other approaches like combined soft and hard template synthesis are also known. An overview of hard-template, soft-template, and template-free procedures are presented in the following paragraphs. 

The development process may be used to select the cluster final size but it occurs also spontaneously any time an even mild reducing agent is present during the radiolytic synthesis. The specificity of this method is to combine the ion reduction successively ... 

Krkljes, A. N., Marinovic-Cincovic, M. T., Zorica, M., Kacarevic-Popovic, Z. M., and J. M. Nedeljkovic. 2007. Radiolytic synthesis and characterization of Ag-PVA nanocomposites. European Polymer Journal 43 2171-2176. 

Radiolytic Synthesis of Radioisotope Metallic NPs and Their Application to... 

RADIOLYTIC SYNTHESIS OF RADIOISOTOPE METALLIC NPS AND THEIR APPLICATION TO RADIOISOTOPE TRACERS... 

Doudna, C. M., Bertino, M. F., Blum, F. D., Tokuhiro, A. T., Lahiri-Dey, D., Chattopadhyay S., Terry, J. 2003. Radiolytic synthesis of bimetallic Ag-Pt nanoparticles with a high aspect ratio. J. Phys. Chem. B 107 2966-2970. 

Souici, A. H., Keghouche, N., Delaire, J. A., Remita, H., and Mostafavi, M. 2006. Radiolytic synthesis and optical properties of ultra-smaU stabilized ZnS nanoparticles. Chem. Phys. Lett. 422 25-29. 

Radiolythic Synthesis PANI-NFs can be produced by irradiating aqueous solutions of aniline, APS, and HCl with y-rays [183]. This template-free radiolytic synthesis of PANI-NFs can be carried out completely in an aqueous phase. The synthesized PANI is virtually... 

Other methods Dilute polymerization, template-free method, rapidly mixed reaction, reverse emulsion polymerization, ultrasonic shake-up, radiolytic synthesis external template the morphology (shape, diameter) poorly or non-oriented ID nanostructures tures such as tubes, wiresZfibers, hoUow microspheres, nanowireZnanotube junctions and dendrites... 

M. Treguer, C. de Cointet, H. Remita, J. Khatouri, M. Mostafavi, J. Amblard, J. Belloni, and R. de Keyzer, Dose rate effects on radiolytic synthesis of gold-silver bimetallic clusters in solution, J. Phys. Chem. B 102,4310-4321 (1998). 

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