自组装合成Fe-N-C-PANI有序介孔结构催化剂及其在酸性条件下的氧还原活性

采用乙醇挥发自组装法，以F127为模版，甲阶酚醛树脂为碳源，聚苯胺为配体，加入硝酸铁和硅酸盐，制备了有序多级孔的Fe-N-C-PANI催化剂.催化剂的成分和形貌表征结果表明，在热处理温度为800℃时，有序介孔的结构最清晰，拥有整齐的孔道和最高的比表面积（1007 m²/g）；XPS分析结果表明，吡啶氮原子和石墨氮原子含量（摩尔分数）为3.86%.热处理温度升高过程中Fe（Ⅲ）被还原，向单质Fe转化，并促进了N的掺杂，使碳化铁转化为Fe-N_x活性位点，提高了催化剂的氧还原反应（ORR）催化活性，热处理温度达到900℃时，过多的单质铁使其氧还原活性下降.在酸性溶液中，Fe-N-C-PANI-800催化剂的起始电位可达0.89 V，半波电势为0.81 V.有序介孔结构使催化剂更易石墨化，提高了材料的稳定性.

Synthesis of Ordered Mesoporous Fe-N-C-PANI Catalyst via Self-assembly and Its Oxygen Reduction Reaction Activity in Acid Medium

Highly ordered mesoporous Fe-N-C-PANI electrocatalysts were synthesized by ethanol evaporation induced self-assembly using triblock copolymer Pluronic F127 as template, phenol-formaldehyde resin as {carbon} precursor and polyaniline as the N precursor.XRD, TEM, BET, XPS and RDE techniques were used to characterize the composition, morphology and electrocatalytic activity of the catalysts.The results show that the catalyst pyrolyzed at 800 ℃ has distinctly ordered mesoporous structure and straightest channel, and its speci-{fic} surface area is as high as 1007 m2/g.The results of XPS show that the percentage of pyidinic N and Graphitic N of Fe-N-C-PANI-800 is 3.86%(molar fraction).In the process of heat treatment, Fe(Ⅲ) was {reduced} to metallic Fe, and the introduction of N was facilitated, which made iron carbide turn into Fe-Nx {active} sites, and enhanced the ORR catalytic performance of catalysts.But when the temperature rise to {900 ℃,} the formation of metallic Fe decreases its ORR activity.In the acid medium, Fe-N-C-PANI-800 has an onset potential of 0.89 V(vs.RHE) and a half-wave potential of 0.81 V(vs.RHE).Ordered mesoporous catalyst had higher graphitization structure, which improved its stability.