Preparation of Ag@mSiO₂ and Pt@mSiO₂nano composites using trioctylmethyl ammonium hydrogen phthalate (TOMAHP) ionic liquid as reaction medium

A novel one step green chemistry approach utilizing trioctylmethyl ammonium hydrogen phthalate (TOMAHP), task specific ionic liquid has been attempted for synthesis of Ag and Pt nanoparticles supported on silica (Ag@mSiO₂ and Pt@mSiO₂). Structure, size distribution and morphology of these nano-composite particles were evaluated using X-ray diffraction (XRD), transmission electron microscopy (TEM), small angle neutron scattering (SANS) as well as small angle X-ray scattering (SAXS) techniques. The XRD results show that Ag/Pt metal nanoparticles deposited on to SiO₂ surface are face center cubic (fcc) in nature. The TEM and SAXS/SANS results show the morphology and size distributions of Ag and Pt nanoparticles loaded on to the surface of SiO₂. It has been found that Ag nanoparticles are well dispersed on to the SiO₂ surface and are quite monodisperse in size, whereas Pt nanoparticles are quite polydisperse in size and forms aggregate or chain like structure on SiO₂ surface containing primary nanoparticles of typical size range 3–7 nm. The stability of nanoparticles, which controls its dispersion on SiO₂ substrate, has been discussed. - Graphical abstract: Mechanism for Ag@mSiO₂ and Pt@mSiO₂ nano composites in TOMAHP ionic liquid medium. - Highlights: • Novel methods for preparation of Pt@SiO₂ and Ag@SiO₂ nano composite in functionalized ionic liquid. • Pt@SiO₂ and Ag@SiO₂ nano composite are characterized using XRD, TEM as well as small angle x-ray scattering techniques. • The sizes of nano composite is <10 nm in size. • The method is simple one step, green chemical reduction method to prepare SiO₂ support nano catalyst.