摘要 :
A tunable synthesis of iron nanoparticles (NPs) based on the decomposition of {Fe[N(SiMe_3)_2]_2}_2 in the presence of organic superstructures composed of palmitic acid and hexadecylamine is reported. Control of the size (from 1.5...
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A tunable synthesis of iron nanoparticles (NPs) based on the decomposition of {Fe[N(SiMe_3)_2]_2}_2 in the presence of organic superstructures composed of palmitic acid and hexadecylamine is reported. Control of the size (from 1.5 to 27 nm) and shape (spheres, cubes, or stars) of the NPs has been achieved. An environment-dependent growth model is proposed on the basis of results obtained for the NP morphology under various conditions and a complete Mossbauer study of the colloid composition at different reacting stages. It involves (ⅰ) an anisotropic growth process inside organic superstructures, leading to monocrystalline cubic NPs, and (ⅱ) isotropic growth outside these superstructures, yielding polycrystalline spherical NPs.
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摘要 :
Highly active rhodium catalysts have been prepared by immobilization of an ionic liquid film on carbon nanotubes functionalized with imidazolium-based ionic moieties.
One of the main drawbacks in homogeneous catalysis concerns th...
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Highly active rhodium catalysts have been prepared by immobilization of an ionic liquid film on carbon nanotubes functionalized with imidazolium-based ionic moieties.
One of the main drawbacks in homogeneous catalysis concerns the difficulty in separating the reaction products from the soluble catalyst and any solvent. This problem becomes even more crucial when expensive noble metal based catalysts are involved. Furthermore, the use of distillation columns increases the energy consumption and often leads to catalyst degradation, increasing the overall cost of the process. Many alternative approaches have been attempted using supported homogeneous catalysts or bipha-sic systems. One very attractive concept combines these approaches by immobilising the catalyst in a thin film of either water or an ionic liquid, absorbed within the pores of a high surface area solid. When ionic liquids (ILs), green, non volatile solvents, are used as a supported phase (supported ionic liquid phase catalysts, SILPCs), long-term reactions have shown promising results. Indeed, the ionic character of ILs confers to these media a spatial organization over several nanometres that induces peculiar solvation phenomena and specific reactivity, which can be linked either to confinement effects in these organized structures or to molecular interactions.
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