银耳状Fe-N-C复合催化剂的制备及催化氧还原性能研究

Preparation and Properties of Tremella-like Fe-N-C Composite Catalyst for Oxygen Reduction Reaction

以无机铁盐和邻苯二胺为基础原料,经铁(Ⅲ)基螯合前驱体热解反应,制备出Fe-N-C复合催化剂。经扫描电镜观察,带有折褶的碳微纳米片相互交迭,形成银耳状的三维自支撑结构。氮气吸脱附测试表明此结构富含微孔和介孔,比表面积可达290 m^2/g。通过X射线衍射(XRD)确证石墨化C和多晶Fe_3C作为催化剂主相存在,X射线光电子能谱(XPS)进一步揭示N原子主要以石墨N和吡啶N形式掺杂到C骨架中。电化学测试表明银耳状Fe-N-C复合催化剂在碱性条件下催化氧还原反应为四电子过程,其催化活性可媲美商业Pt/C催化剂。经过2000次氧还原测试后,催化极限电流衰减小于5%,并且半波电势仅负移5 mV(商业Pt/C催化剂负移35 mV),表现出优异的氧还原催化稳定性。

The Fe-N-C composite catalyst was prepared by the thermal decomposition of the chelate precursors based on Fe（Ⅲ） central ions and o-phenylenediamine ligands. It was observed from the scanning electron microscopy that the crumpled carbon micro-and nano-sheets were intertwined to form a free-standing tremellalike 3D structure. The N2 adsorption/desorption experiments revealed that the composite contained ample micro-and meso-pores and had a specific surface area of 290 m2/g. Graphitic C and multi-crystal Fe3C as main components were confirmed by the X-ray diffraction,and N-doping in the general form of graphite N and pyridine N was also verified by X-ray photoelectron spectroscopy. The electrochemical measurement showed that the tremella-like Fe-N-C composite catalyzed oxygen reduction through a four-electron path in an alkaline solution,and its activity was comparable to the commercial Pt/C catalyst. After 2000 cycles,the limited current density of the Fe-N-C catalytic electrode only decreased less than 5%,and the half-wave potential shift negatively 5 mV,which suggested that the Fe-N-C composite catalyst had better catalytic stability than the commercially used Pt/C catalyst.