Strawberry-like SiO2@Pd and Pt nanomaterialsElectronic supplementary information (ESI) available. See DOI: 10.1039/c4nj01019a

Based on a synthesis strategy of silica nanoparticles (NPs) in non-alcoholic medium, a straightforward protocol leading to strawberry-like SiO 2 @M nanomaterials (M = Pt, Pd) has been developed. Pd and Pt NPs were immobilised onto surface modified silica NPs, by in situ decomposition of organometallic precursors, Pd 2 (dba) 3 and Pt(dba) 2 (dba = dibenzylideneacetone). The surface of silica was functionalised by aminopropyltriethoxysilane (APTES) or 2-(diphenylphosphino)ethyltriethoxysilane (PhPETES). The co-grafting of propyltriethoxysilane (PTES) and APTES was investigated to avoid the classical interfering cohydrolysis and polycondensation reactions which can lead to agglomeration phenomena between the silica NPs. It appeared that a APTES/PTES ratio of 1/3 insured a dense and homogeneous deposition of the metallic NPs onto silica. Depending on the ligand, the diameter of the metallic NPs varies from 3.6 to 6.0 nm for Pd and from 1.5 to 3.1 nm for Pt NPs. The metal loading is adjustable, at least up to 6.91 wt%, as exemplified with Pd. Preliminary catalytic tests of the SiO 2 @Pd nanomaterial are also presented. Pd and Pt nanoparticles (NPs) supported on silica particles were prepared via a straightforward protocol in non-alcoholic medium. The metallic NPs are remarkably dense, homogeneous and well-dispersed at the silica surface.