酸处理对FeN/ZIF-8催化剂氧还原反应催化性能的影响

研发高性能、低成本的非贵金属阴极氧还原反应催化剂是目前质子交换膜燃料电池的主要研究方向之一。以1, 10-菲啰啉为氮源, FeSO₄·7H₂O为铁源, 考察以ZIF-8为载体制备的FeN/ZIF-8催化剂的氧还原反应催化性能, 并探究酸处理对FeN/ZIF-8催化剂结构及性能的影响。通过X射线衍射、比表面积和孔径分布测试、透射电子显微镜等物理表征手段对催化材料进行结构表征, 使用旋转圆盘电极对催化剂氧还原反应催化活性和稳定性进行测试。结果表明: 以ZIF-8为载体制备的催化剂含有Fe₃C, 以及具有较大的比表面积, 这可能是催化剂具有较高氧还原反应初始催化活性的原因。酸处理可去除催化剂中部分不稳定的含铁碳化物和无序碳结构, 使催化剂具有更大的比表面积、更丰富的介孔结构和更高的孔体积; 同时, 酸处理可提高碳基体的耐腐蚀性, 在老化测试中维持催化剂所具有的较高比表面积和丰富的介孔结构, 从而使FeN/ZIF-8-A催化剂表现出更好的氧还原反应活性和稳定性。

Effect of acid treatment on catalytic performance of FeN/ZIF-8 catalyst for oxygen reduction reaction

The development of non-noble metal catalysts with high-performance and low-cost for oxygen reduction reaction is one of the main research directions in proton exchange membrane fuel cells.The catalytic performance of the FeN/ZIF-8 catalysts was investigated using ZIF-8, 1, 10-phenanthroline and FeSO₄·7H₂O as carbon support, nitrogen and iron precursor, respectively. The effects of acid treatment on structure and catalytic performance of FeN/ZIF-8 catalyst were also explored by various techniques. The structure of catalysts was characterized by X-ray diffraction, specific surface area and pore size distribution measurements and transmission electron microscopy, etc. The catalytic activity and stability of the catalysts for oxygen reduction reaction were investigated by linear sweep voltammetry and accelerated degradation test. The results show that the catalysts with ZIF-8 as the carbon support have high initial catalytic activity for oxygen reduction reaction due to their high specific surface area and the existence of Fe₃C in catalysts. The acid treatment can remove some unstable iron-containing carbides and disorder carbon in the catalyst. The structure of the FeN/ZIF-8-A catalyst is modified by acid treatment. The higher specific surface area, more abundant mesoporous structure and higher pore volume, as well as the improved resistance to corrosion in acid solution are the key reasons of FeN/ZIF-8-A catalyst with better catalytic activity and stability for oxygen reduction reaction in acid environment.