XRD and M?ssbauer studies on Pt–Fe nano-particles synthesized by polyol method for cathode catalyst of PEFCS

摘要

Pt50–Fe50 nanoparticles were synthesized by the chemically wet process for developing a new high efficiency cathode catalyst in PEFCs. The particle morphology and crystal structure of as synthesized Pt–Fe particles, and electronic state of Fe atoms in them were evaluated using transmission electron microscopy(TEM), X-ray diffraction(XRD) and transmission M?ssbauer spectroscopy (TMS), respectively. They are confirmed to be of chemically disordered fcc structure from XRD pattern and the average diameter of them was estimated to be 3.1 nm from both TEM and the width of (111) peak in XRD pattern. From TMS spectrum, it was concluded to consist of mainly the component of Fe oxides connected with the organic ligands according to XPS results mentioned below. But, probably it contains the component for superparamagnetic Pt–Fe nanoparticles. Also the electrocatalytic activity and a hydrogen adsorption/desorption behavior for as synthesized Pt–Fe nanoparticles was observed by cyclic voltammetry and the oxidation of Fe atoms in as synthesized Pt–Fe nanoparticles, Fe metal and Fe oxides were measured.