铁氮掺杂活性炭载体增强碳载铂基催化剂氧还原反应稳定性

Enhanced stability for oxygen reduction reaction of supported platinum-based catalyst with Fe-N doped activated carbon as carbon support

修饰和改良载体是改善质子交换膜燃料电池阴极铂基催化剂性能的主要途径。以铁氮(FeN)掺杂活性炭(Black Pearl 2000,BP)为载体,获得负载型铂基催化剂。使用电化学方法对催化剂的氧还原反应活性以及稳定性进行测试,采用X射线衍射仪、比表面积和孔径分布测试、透射电子显微镜、X射线光电子能谱等分析手段对载体及催化剂结构进行表征。结果表明:Pt/FeN-BP催化剂与商业Pt/C催化剂的起始电位均为0.94 V,具有相当的氧还原反应初始活性;老化测试后,Pt/FeN-BP催化剂与商业Pt/C催化剂的起始电位损失分别约为10,30 mV,半波电位损失分别约为5,60 mV,Pt/FeN-BP催化剂的稳定性明显优于商业Pt/C催化剂。这是因为,铁氮掺杂碳载体具有适中的比表面积和孔径大小,Pt颗粒在载体上以小粒径的状态存在且老化测试后Pt颗粒无团聚现象,以及载体与Pt颗粒之间可能存在一定的相互作用。

Modification and doping of carbon support are the main ways to improve the performance of the platinum-based catalyst for proton exchange membrane fuel cell.FeN-BP.Iron and nitrogen(FeN)co-doped activated carbon(Black Pearl 2000,BP)as a support,was used as the support of platinum-based catalyst for oxygen reduction reaction(ORR).The activity and stability of the catalysts were tested by electrochemical techniques,and the structure of the catalysts were characterized by X-ray diffraction,specific surface area and pore size distribution test,transmission electron microscopy,X-ray photoelectron spectroscopy.The results show that Pt/FeN-BP and commercial Pt/C catalyst have comparable initial ORR activity with onset potential 0.94 V.After accelerated degradation test,the lost of onset potential for Pt/FeN-BP catalyst and commercial Pt/C catalyst are about 10 mV and 30 mV,as well as the lost of half-wave potential are about 5 mV and 60 mV.Pt/FeN-BP catalyst shows obvious improved stability.The high surface area and the moderate pore size distribution of FeN-BP,the small size and well dispersion of Pt nanoparticles on carbon after accelerated degradation test,as well as the interaction between carbon support and Pt nanoparticles may the key reasons for Pt/FeN-BP with improved stability.