Chemical synthesis and silica encapsulation of NiPt nanoparticles

NiPt nanoparticles were one-step synthesized by the reduction of nickel acetylacetonate and platinum acetylacetonate in the presence of oleic acid and oleylamine as stabilizers. The as-synthesized NiPt nanoparticles have a face-centered-cubic (fcc) structure. Silica shells were then coated with tunable thickness from 8 to 16 nm that could be controlled by varying the ratio of the NiPt nanoparticles to the silica precursor. This is the first study of NiPt@SiO2 (core/shell) nanoparticles. The size of the nanoparticles was confirmed by transmission electron microscopy (TEM). The crystal structure was characterized by X-ray diffraction pattern (XRD). The chemical structure and morphology were studied with X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray microanalysis (SEM-EDX). The magnetic properties were characterized by a superconducting quantum interference device (SQUID).