还原热处理条件对Pt-Fe/C合金催化剂性能的影响

Effect of the Reduction Heat-Treatment Condition on the Performance of Pt-Fe/C Alloy Catalyst

采用脉冲微波辅助化学还原-含氢气体热处理法制备了质子交换膜燃料电池(PEMFC)用Pt-Fe/C合金催化剂.通过电感耦合等离子体(ICP)检测了金属元素含量,用透射电镜(TEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)等技术对催化剂的微观结构和形貌进行了表征,并利用循环伏安(CV)法评价了催化剂催化氧还原性能.结果表明,脉冲微波辅助化学还原法是一种快速制备粒径较小、分布均匀的Pt-Fe/C催化剂的有效方法,含氢气体热处理对提高催化剂活性有重要作用.还原热处理温度和时间对催化剂活性也有很大影响.经过500°C还原热处理后的催化剂活性比还原热处理之前的催化剂性能有很大提高.TEM和XRD结果显示,Pt-Fe/C-500-3h的纳米粒子均匀地分散在碳载体上,平均粒径为1.8nm,500°C下热处理3h的催化剂有最大的电化学表面积(ESA),为55.14m2·g-1.

Pt-Fe/C catalyst for proton exchange membrane fuel cell （PEMFC） was prepared by a pulse-microwave assisted chemical reduction heat-treatment synthesis method. The elemental content was tested by inductively coupled plasma （ICP）. The microstructure and morphology of the as-prepared catalyst were characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, and X-ray photoelectron spectroscopy （XPS）. The electrocatalytic performance was measured by cyclic voltammetry （CV）. The results indicate that pulse-microwave assisted chemical reduction heat-treatment synthesis is an efficient method for preparing PEMFC catalysts while the temperature and time of heat treatment greatly affect the size and activity of the Pt-Fe nanoparticles. For a heating temperature of 500 ℃ and a time of 3 h the Pt-Fe nanoparticles were uniform in size. Moreover, the Pt-Fe/C-500-3h alloy catalyst was highly dispersed on the surface of the carbon support and the TEM and XRD showed that the average Pt-Fe nanoparticle size was 1.8 nm. The electrochemical measurements show that the electrochemical surface area （ESA） of the catalyst was 55.14 m^2· g^-1.