Hierarchical meso-micro porous FeNC derived from tripolycyanamide-based microporous polymer as efficient...

Designing porous FeNC nanomaterials with highly efficient active sites is an effective strategy for constructing high-performance oxygen reduction reaction (ORR) electrocatalysts. N-containing porous organic polymers (POPs) have emerged as promising candidates for the preparation of porous FeNC catalysts. Here, N-rich tripolycyanamide-based microporous polymer (TCAMP)-coated SiO₂ nanospheres (SiO₂@TACMP) were prepared as the precursors of an Fe-N doped hierarchical meso-micro porous carbon (Fe-N-HMC) electrocatalyst for the ORR. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) characterizations demonstrated that the Fe-N-HMC catalyst possessed a higher content percentage of Fe-N_x active sites and a better distribution of Fe nanoparticles than its Fe-N doped microporous carbon (Fe-N-MC) counterpart. N₂ adsorption-desorption isotherm analysis showed that Fe-N-HMC catalyst exhibited a hierarchical meso-micro porous system, with a Brunauer-Emmett-Teller (BET) surface area (S_BET) of 733 m² g^-1 (∼2 times of Fe-N-MC's S_BET). As a result, Fe-N-HMC catalyst presented a highly efficient ORR performance with a half-wave potential of 0.856 mV, which is similar to the commercial grade 20 wt% Pt/C catalyst and superior to the Fe-N-MC catalyst. Moreover, the as-synthesized Fe-N-HMC catalyst displayed a better durability and methanol tolerance than the commercial Pt/C catalyst. Therefore, Fe-N-HMC shows great promise as an ORR catalyst for fuel batteries and metal-air cells due to its low-cost, high activity, and good stability.