Multi-walled carbon nanotubes (MWCNT) and nanofibers (CNF) have been functionalized at their surfaces with chelating phosphine (PPh 2) and ammonium (NMe 3 +) groups, as anchoring sites for metal complexes. The surface functionalization has been monitored by XPS, elemental analyses, N 2 physisorption and/or SEM surface morphology analysis at each step. Bimetallic Fe-Co nanoparticles from two different starting cluster complexes, [HFeCo 3 (CO) 12 ] (1) and (NEt 4)[FeCo 3 (CO) 12 ] (2), have been deposited onto the surfaces of the functionalized MWCNT and CNF as well as their pristine forms for comparison. The samples have been fully characterized before and after thermal treatment. The obtained nanoparticles were shown by TEM to be better dispersed and of smaller size on functionalized than on pristine supports. Magnetic characterization revealed blocked superparamagnetic Fe-Co nanoparticles together with paramagnetic ions on CNF as well as MWCNT.

Two mixed-metal clusters, [Ru 5 PtC(CO) 14 (COD)] (1) and [Ru 6 Au 2 C(CO) 16 (PPh 3 ) 2 ] (2), were anchored onto a prefunctionalized active carbon support (C PPh 2 ) with chelating phosphane groups on its surface. These clusters were also deposited onto the unmodified support (C SX+ ) for comparison. The incorporation of 1 and 2 on both supports was studied by a combination of SIMS and XPS. When the clusters were anchored onto the functionalized carbon support, SIMS spectra displayed characteristic patterns that were different from those obtained in the case of their deposition on the unmodified support. In the latter case, spectra corresponded to the results obtained with pure unsupported clusters. XPS analyses of the supported species seemed to indicate that the stoichiometry of the clusters was retained after anchoring and that their dispersion was better on C PPh 2 than on C SX+ . This indicates that the phosphanes act as anchors for noble metal compounds through a ligand exchange mechanism. The sup-

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SummaryHeterometal clusters containing Ru and Au, Co and/or Pt are anchored onto carbon nanotubes and nanofibers functionalized with chelating phosphine groups. The cluster anchoring yield is related to the amount of phosphine groups available on the nanocarbon surface. The ligands of the anchored molecular species are then removed by gentle thermal treatment in order to form nanoparticles. In the case of Au-containing clusters, removal of gold atoms from the clusters and agglomeration leads to a bimodal distribution of nanoparticles at the nanocarbon surface. In the case of Ru–Pt species, anchoring occurs without reorganization through a ligand exchange mechanism. After thermal treatment, ultrasmall (1–3 nm) bimetal Ru–Pt nanoparticles are formed on the surface of the nanocarbons. Characterization by high resolution transmission electron microscopy (HRTEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) confirms their bimetal nature on the nanoscale. The obtained bimetal nanoparticles supported on nanocarbon were tested as catalysts in ammonia synthesis and are shown to be active at low temperature and atmospheric pressure with very low Ru loading.

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