Ordered macroporous carbonous skeletons implanted with dual-phase Co/CoFe nanoparticles for boosting electrocatalytic performance

The accessibility of active sites is crucial to electrochemical applications, therefore, rationally controlled synthesis of novel electrocatalysts with favorable mass transfer and active site exposure is imperative. In this work, ordered macroporous N-doped carbonous skeletons implanted with dual-phase Co/CoFe nanoparticles are successfully synthesized by directly pyrolyzing Fe³⁺-incorporated ZIF-67 (ZIF = zeolitic imidazolate framework), which are pre-synthesized by confined growth of Fe³⁺/ZIF-67 inside the ordered voids of well-assembled polystyrene template. The incorporated Fe species not only benefits the formation of dual-phase Co/CoFe active sites, but also activates the carbon skeletons by enhancing the content of pyridine-N. Benefiting from the favorable accessibility of these active sites caused by the macroporous structure, the Co/CoFe_2.5@OMNC sample exhibits good performance toward oxygen reduction reaction (ORR) with four-electron transfer pathway. More importantly, the Co/CoFe_2.5@OMNC sample retains the activity even after 10,000 sweeping cycles of durability test, which outperforms commercial Pt/C-20% and other samples.