Synthesis and Evaluation of Pt-Fe Alloy Nano-Particles for Cathode Catalyst of Polymer Electrolyte Fuel Cells

为了<50><50>开发新型高效聚合物电解质燃料电池阴极催化剂，采用化学湿法合成了Pt_ -Fe_2纳米粒子。采用透射电子显微镜（TEM）、X射线衍射仪（XRD）、透射穆斯堡尔谱仪（TMS）和X射线光电子能谱仪（XPS）分别对合成的Pt-Fe粒子的形貌、晶体结构和Fe原子的电子状态进行了表征。XRD图谱证实它们为化学无序的面心立方结构，TEM和XRD图谱中（111）峰的宽度估计它们的平均直径为3.1nm。从TMS光谱，得出的结论是，它们主要由与有机配体连接的铁氧化物的组分，考虑到XPS结果。但是，它可能含有超顺磁性Pt-Fe纳米粒子的成分。此外，还研究了它们的电催化活性和氢吸附/脱附行为。 ...更多信息 用循环伏安法观察了合成的Pt-Fe纳米粒子的电化学行为，并测定了合成的Pt-Fe纳米粒子、金属铁和铁氧化物中Fe原子的氧化行为。XPS分析表明，Ar溅射法可以部分去除Pt Fe纳米粒子中与有机配体相连的Fe氧化物，并将其暴露于H2等离子体中得到金属Pt Fe纳米粒子。630℃保温5 min退火后，在Ar+4%H_2气氛中，用XRD和TMS观察到了有序的fct结构。本文对金属Pt-Fe纳米颗粒及其退火样品进行了CV曲线的测定，并<50><50>利用等离子体-气体凝聚技术（Plasma-Gas-Condensation Technique）初步合成了用于PEFC阴极催化剂的Pt-Fe合金纳米团簇。用穆斯堡尔谱（MS）和卢瑟福背散射（RBS）分析分别测定了它们的组成和铁的电子态。用XPS和低温MS研究了Pt-Fe合金纳米团簇中Fe原子的化学状态。研制了由Avarache光电二极管和CsI（Tl）晶体组成的低能X射线探测器，在不冷却的情况下探测了14.4keV的γ射线，并尝试用Peltier装置测量5.9keV的Fe的K射线<55>，用于冷却的转换X射线穆斯堡尔谱。少

Pt_<50>-Fe_<50> nanoparticles were synthesized by the chemically wet process for developing a new high efficiency cathode catalyst in Polymer-Electrolyte Fuel Cells(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), transmission Mossbauer spectroscopy(TMS) and X-ray Photoelectron Spectroscopy(XPS), 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 that they consist of mainly the component of Fe oxides connected with the organic ligands in consideration of XPS results. But, probably it contains the component for superparamagnetic Pt-Fe nanoparticles. Also the electrocatalytic activity and a hydrogen adsorption/desorption behavior fo … More r 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. It is confirmed by XPS that Fe oxides connected with the organic ligands in as synthesized Pt-Fe nanoparticles can be removed partially by Ar sputtering and the metallic Pt-Fe nanoparticles were obtained by exposing the as synthesized to H_2 soft plasma. Furthermore, as annealed sample at 630℃ for 5min. in Ar+4%H_2 atmoshere was observed to be ordered fct structure by XRD and TMS. At the present, the measurements of CV curves for the metallic Pt-Fe nanoparticles and as annealed samples are prepared.Pt_<50>-Fe_<50> alloy nano-clusters for cathode catalyst of PEFCs were also synthesized tentatively by using a Plasma-Gas-Condensation Technique. The composite and electronic states of Iron for them have been evaluated by Mo ssbauer spectroscopy (MS) and, Rutherford Back-Scattering (RBS) analysis, respectively. It was found that the sample includes α-Fe component and chemical state for Fe atoms in Pt-Fe alloy nano-clusters has to be investigated by XPS measurement and low temperature MS.Low energy X-ray detector which consist of avarache photodiode and CsI(Tl) scintillater has been developed to detect 14.4 keV γ-ray without cooling and now is tried to measure 5.9 keV K X-ray of ^<55>Fe for Conversion X-ray Mossbauer spectroscopy with cooling by Peltier device. Less