Datensatz

Zusammenfassung

The area of nanoparticle synthesis has gained interest in the past few years due to their potential and application in areas such as micro-electronics and selective catalysis.[1] In the case of metal nanoparticles, their properties are often related to their size and shape, and therefore controlling their growth has been an area of active research for dec-ades.[2] In the specific case of supported metal nanoparti-cles, some control is possible by changing the precursor, the method of impregnation, the nature of oxide support and the final decomposition method. Using perhydrocarbyl complex precursors provides some advantages because of their ease of decomposition under H2, which leads to metal surfaces free of strong ligands such as CO or Cl-. The mean particle size can be somewhat controlled by the choice of the support, which directs the migration of the zero valent ensembles in the process of the crystal growth, but the re-sulting particles are usually large (> 1 nm). Even if the organometallic precursor is first grafted to the support to insure a high dispersion, treatment under H2 at high tem-peratures leads to the cleavage of the M-O bond and to sintering, yielding large supported metal particles.[3] Con-trolling or even avoiding the sintering process on oxide supports by the means of surface organometallic chemistry tools would lead to smaller nanoparticles of a few atoms (<1 nm) or analogues of the early transition-metal surface hydrides,[4] which could be of great interest for catalytic applications.