Synthesis and Characterization of Core−Shell FePt@Ti-Containing Silica Spherical Nanocomposite as a Catalyst Carrier for Liquid-Phase Reactions

Colloidal FePt nanoparticles stabilized by oleic acid and oleylamine were modified through a ligand exchange with (3-mercaptpropyl)-trimethoxysilane. The particles were subsequently treated using the so-gel route with tetraethyl orthosilicate and tetrapropylorthotitanate. A new nanocomposite (FePt@Ti-SiO 2 ) was characterized by means of X-ray diffraction, IR, transmission electron microscopy, superconducting quantum interface device, and X-ray absorption fine structure measurements. The face-centered cubic FePt NPs with a mean diameter of ca. 6 nm were encapsulated in the Ti-SiO 2 thick shell, which exhibited superparamagnetic behavior at 300 K with zero remanence and coercivity. The Ti-oxide moiety was proven to exist in the isolated and tetrahedral form. The FePt@Ti-SiO 2 served as an efficient nanocatalyst for the liquid-phase selective epoxidation using hydrogen peroxide (H 2 O 2 ). Recovery from the reaction mixture was readily attained by applying an external permanent magnet, and the spent catalyst could be recycled without any appreciable loss in activity.