铁前驱体对FeN/ZIF-8催化剂氧还原活性的影响

Effect of iron precursors on oxygen reduction reaction activity of FeN/ZIF-8 catalysts

近年来,ZIF-8因具有比表面积大、孔道结构规则等优点而被用作氧还原催化剂载体。以ZIF-8为载体,1,10-菲啰啉为氮源,分别以FeSO_(4)·7H_(2)O,FeAc,FeCl_(3)·6H_(2)O和FeC_(10)H_(10)为铁前驱体制备阴极氧还原催化剂,考察不同铁前驱体对FeN/ZIF-8催化剂结构及性能的影响。使用X射线衍射、比表面积和孔径分布测试、透射电子显微镜、热重分析等方法对催化剂的结构、形貌及催化剂前驱体的热性质等进行表征,使用线性扫描伏安法对催化剂的氧还原活性进行测试。结果表明:以FeSO_(4)·7H_(2)O为铁前驱体制备的催化剂,其起始电位约为0.93 V,氧还原反应为4电子过程,具有更好的氧还原催化活性;其在制备过程中形成的适中的比表面积及孔径大小,较好的晶型结构及较均匀的颗粒分散情况,且X射线衍射结果表明催化剂中存在少量的Fe_(3)C,这是其具有较好的氧还原催化活性的可能原因。

ZIF-8 attracted more attention as the carbon support for oxygen reduction reaction catalyst due to its large specific surface area and regular pore structure in recent years.A series of FeN/ZIF-8 catalysts were prepared using ZIF-8,1,10-phenanthroline as carbon and nitrogen precursor,as well as FeSO_(4)·7H_(2)O,FeAc,FeCl_(3)·6H_(2)O and FeC_(10)H_(10) were used as different iron precursors,respectively.The influence of different iron precursors on the structure and oxygen reduction reaction(ORR)activities of FeN/ZIF-8 catalysts were investigated by X-ray diffraction,specific surface area and pore size distribution measurements,transmission electron microscope,thermogravimetric analysis,and linear sweep voltammetry.The results show that the catalyst prepared with FeSO_(4)·7H_(2)O as iron precursor has the initial potential of about 0.93 V,and the ORR is a four-electron process,which has better oxygen reduction catalytic activity.Moderate specific surface area and pore size distribution,good crystal structure and uniform particle dispersion,as well as the presence of Fe_(3)C are the possible reasons of resulting in better ORR activity of FeN/ZIF-8 with FeSO_(4)·7H_(2)O as the iron precursor.