Low-temperature synthesis of superparamagnetic nanocomposite particles composed of platinum and maghemite

Superparamagnetic nanocomposite particles composed of maghemite nanocrystal (ca.15 nm) and deposited Pt nanoclusters (ca. 2.5 nm) were synthesized by a low temperature catalytic method. The magnetic properties of iron oxides species can be easily tuned with different redox atmosphere in the presence of Pt nanoclusters. In this convenient preparation, Pt nanoclusters were first captured on Fe(OH)(3) nanoparticles by electrostatic interaction. Then at 80 'C the Fe(OH)(3) nanoparticles was catalytically reduced with glycol acid to Fe2O3 nanophase which were finally catalytically oxidized to maghemite (gamma-Fe2O3) nanophase in the air at 80 degrees C. The as-synthesized Pt/Fe2O3 and Pt/gamma-Fe2O3 nanocomposites were well characterized by chemical analysis, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and magnetization measurements. Reversible and efficient transformation between the Pt/Fe2O3 and Pt/gamma-Fe2O3 nanocomposites was realized at 80 degrees C. The Pt/gamma-Fe2O3 nanocomposite particles modified with oleic acid were easily dispersed in nonpolar solvents such as hexane, resulting in stable ferrofluids.Chemistry, PhysicalNanoscience & NanotechnologyMaterials Science, MultidisciplinarySCI(E)EI0ARTICLE2910688-1069111