  The formation of monodisperse, tunable sized, alloyed nanoparticles of Ni,
Co, or Fe with Pt and pure Pt nanoparticles attached to carbon nanotubes has
been investigated. Following homogeneous nucleation, nanoparticles attach
directly to non-functionalized singlewall and multiwall carbon nanotubes during
nanoparticle synthesis as a function of ligand nature and the nanoparticle work
function. These ligands do not only provide a way to tune the chemical
composition, size and shape of the nanoparticles but also control a strong
reversible interaction with carbon nanotubes and permit controlling the
nanoparticle coverage. Raman spectroscopy reveals that the sp2 hybridization of
the carbon lattice is not modified by the attachment. In order to better
understand the interaction between the directly attached nanoparticles and the
non-functionalized carbon nanotubes we employed first-principles calculations
on model systems of small Pt clusters and both zig-zag and armchair singlewall
carbon nanotubes. The detailed comprehension of such systems is of major
importance since they find applications in catalysis and energy storage.
