title: From well-defined Pt(II) surface species to the controlled growth of silica supported Pt nanoparticles.
abstract: Silica-supported Pt nanoparticles were prepared from well-defined surface platinum(II) surface species, obtained by grafting of well-defined Pt(II) molecular precursors with specific ligands (Cl, Me, N(SiMe(3))(2), OSi(OtBu)(3)) onto silica partially dehydroxylated at 200 and 700 °C yielding well-defined platinum(II) surface species. This approach allowed for testing the effect of Pt density and ligands on nanoparticle size. Higher grafting densities are achieved on silica partially dehydroxylated at 200 °C due to its initially higher surface silanol density. Surface species have been synthesized from symmetrical and dissymmetrical complexes, namely (COD)Pt(Me)(2), (COD)Pt(OSi(OtBu)(3))(2), (COD)Pt(Me)(OSi(OtBu)(3)), (COD)Pt(Me)(N(SiMe(3))(2)), (COD)Pt(Cl)(N(SiMe(3))(2)) and (COD)Pt(N(SiMe(3))(2))(OSi(OtBu)(3)) yielding mono-grafted complexes of general formula (COD)Pt(R)(OSi≡) according to elemental analyses, diffuse reflectance infrared fourier transform (DRIFT) and carbon-13 solid-state nuclear magnetic resonance (NMR) spectroscopies. While the dimethyl-complex shows low reactivity towards grafting, bis-siloxy and dissymmetric complexes demonstrate better reactivity yielding platinum loadings up to 7.4 wt%. Upon grafting amido complexes, the surface passivation yielding Me(3)SiOSi≡ surface species is demonstrated. Nanoparticles have been synthesized from these well-defined surface species by reduction under H(2) at 300 °C, under static or flow conditions. This process yields nanoparticles with sizes ranging from 2 to 3.3 nm and narrow size dispersion from 0.5 to 1.2 nm. Interestingly, the chloride complex yields large nanoparticles from 5 to 40 nm demonstrating the strong influence of chloride over the nanoparticles growth.
authors.affiliation: Institut de Chimie de Lyon, UMR C2P2, CNRS, Université Lyon 1, ESCPE Lyon, Equipe Chimie Organométallique de Surface 43, Bd du 11 Novembre 1918 F-69616, Villeurbanne, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Laurent
authors.forename: Laurent
authors.initials: L
authors.lastname: Veyre
authors.forename: Chloé
authors.initials: C
authors.lastname: Thieuleux
authors.forename: Sébastien
authors.initials: S
authors.lastname: Donet
authors.forename: Christophe
authors.initials: C
authors.lastname: Copéret
mesh_terms: D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D053768:Metal Nanoparticles / Q000737:chemistry*; D008968:Molecular Conformation; D010984:Platinum / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D010984:Platinum; D012822:Silicon Dioxide