Surfactants-Mediated Method is adapted in the chemical synthesis of FePt nanoparticles. The size and structure of FePt nanoparticles can be simply tuned by controlling the surfactants/solvent ratio and reaction temperature. These simply-tuned FePt nanostructures show spherical, nanocubes and nanowires/nanorods. As-synthesized near equiatomic FePt nanoparticles show chemically disordered face centered cubic (fcc) structure, which is superparamagnetic. Through high temperature heat treatment, the fcc-structured FePt nanoparticles can be changed into chemically ordered face centered tetragonal (fct) structure, which is ferromagnetic. This fct-structured FePt nanoparticles show high magnetocrystalline anisotropy constant K, reaching up to 107 J/m3 along easy axis [001] direction, that is one of the largest among the known hard magnetic materials. To block sintering problem during annealing process, MgO is coated on fcc-FePt nanoparticles, which is high temperature endurable robust material and easy removable by dilute acid after thermal treatment. Phase changed fct-FePt nanoparticles can be dispersed in hexane solution by aid of hexadecanethiol and oleic acid without severe agglomeration. All these series of progress may offer the fabrication of ordered nanomagnet arrays with controlled magnetic alignment, which is an important goal to achieve high density information storage and high performance permanent magnets. Pt-based metal alloys can be also used as electrocatalysts in fuel cells. They catalyze hydrogen oxidation at the anode and oxygen reduction at the cathode, especially in Proton Exchange Membrane (PEM) fuel cells. Platinum catalysts without any secondary metal element, however, are very expensive, which hinders the development of large scale fuel cell applications. To reduce the costs of fuel cells and improve the performance, a nanosized FePt electrocatalysts have been prepared and evaluated for anodic and cathodic electron-transfer reactions. FePt nanoparticles as electocatalysts show good performance in both oxygen reduction reactions at cathode and small molecule (methanol and formic acid) oxidation reactions at anode.
Kim, Jaemin,
"The Magnetic and Electrocatalytic Studies of FePt Nanoparticles"
(2009).
Chemistry Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0XW4H21
