Synthesis and characterization of catalytic iridium nanoparticles in imidazolium ionic liquids.
The reduction of [Ir(cod)Cl](2) (cod=1,5-cyclooctadiene) dissolved in 1-n-butyl-3-methyl tetrafluoroborate, hexafluorophosphate and trifluoromethane sulphonate ionic liquids in the presence of 1-decene by molecular hydrogen produces Ir(0) nanoparticles. The formation of these nanoparticles follows the two-step [A-->B, A+B-->2B (k(1),k(2))] autocatalytic mechanism. The same mean diameter values of around 2-3 nm were estimated from in situ TEM and SAXS analyses of the Ir(0) nanoparticles dispersed in the ionic liquids and by XRD of the isolated material. XPS and EXAFS analyses clearly show the interactions of the ionic liquid with the metal surface demonstrating the formation of an ionic liquid protective layer surrounding the iridium nanoparticles. SAXS analysis indicated the formation of an ionic liquid layer surrounding the metal particles with an extended molecular length of around 2.8-4.0 nm depending on the type of the anion.
Fonseca
Gledison S
GS
Laboratory of Molecular Catalysis, Institute of Chemistry and Institute of Physics, UFRGS, Avenida Bento Gonçalves, 9500 Porto Alegre, RS 91501-970, Brazil.
Machado
Giovanna
G
Teixeira
Sergio R
SR
Fecher
Gerhard H
GH
Morais
Jonder
J
Alves
Maria C M
MC
Dupont
Jairton
J