Ultrasonic Synthesis and Characterization of γ-Fe2O3/M (M=Pt, Pd) Nanocomposites for Magnetosensitive Catalyst

The surfaces of maghemite nanoparticles prepared from magnetite by calcination process, were modified by 3-triethoxysilylpropylamine (APTES). The chloroplatinic acid/palladium chloride was added into APTES-maghemite NPs solution, and accordingly, the Pt4+/Pd2+ was absorbed on the surface and formed a coordinated compound with amino groups. Finally, the complexed Pt4+/Pd2+ was reduced by hydrazine hydrate (HHA) to generate magnetic gamma-Fe2O3/M (M=Pt/Pd) nanocomposites under ultrasonic application. The morphology, microstructure, composition and magnetic properties of the gamma-Fe2O3/M NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM) and superconducting quantum interference device (SQUID) magnetometry. The results show that the diameters of precursor maghemite nanoparticles are about 20 nm, and those of the gamma-Fe2O3/Pt and gamma-Fe2O3/Pd nanoparticles are about 68 and 36 Inn, respectively. Their magnetic performances have shown a saturation magnetization (M-s) of about 29.4 and 31.2 (A.m(2))/kg at room temperature, respectively. The superior magnetic response property for magnetic sensitive catalyst system will be further investigated. These kinds of nanoparticles have provided a new way for recovering of Pt and Pd catalyzer and application of magnetosensitive catalyst system.