Preparation Fe–N–C catalyst for ORR with high pyridine-type FeN4 based on nano-SiO2 shell coating method

In this paper, we present a method to enhance the stability of Fe–N–C electrocatalysts, known for their significant oxygen reduction reaction (ORR) activity and positioned as promising alternatives to commercial noble metal-based catalysts. Despite the favorable ORR activity, Fe–N–C suffers from inadequate stability in acidic media, primarily attributed the loss of active FeN4 sites resulted from Fe-demetalation. However, recent investigation reveals that pyridine N exhibits remarkable stability in retaining Fe atoms. To address this, we achieved a high proportion of pyridine N doping in carbon nanofibers through a process involving nano-SiO2 shell coating and electrospinning. The nano-SiO2 shell coating method demonstrates efficacy and versatility in transforming pyrrole-type FeN4 into pyridine-type FeN4, irrespective of the origin material being trivalent or divalent Fe, whether organic or inorganic.