Bimetal/Metal Oxide Encapsulated in Graphitic Nitrogen Doped Mesoporous Carbon Networks for Enhanced Oxygen Electrocatalysis

In this study, Fe doped, Co and CoO encapsulated N doped carbon frameworks were prepared from simple hybrid zeolite imidazole frameworks (ZIF) with extra N enrichment. The facile strategy included preparation of ZIF-8 core and ZIF-67 shell and later replacing the metal centers of ZIF with Fe ions and increasing the N content with N rich melamine. The metal and metal oxide components got captured and encapsulated in the N doped mesoporous carbon frameworks through a pyrolysis process at different temperatures. Fe, Co and CoO were trapped in the N doped mesoporous carbon networks through annealing and denoted as FCNCx. The activity and electrochemical stability of such prepared materials towards ORR and OER were tested in basic media. After analyzing rotating disk electrode studies, FCNC900 was seen to perform superior bifunctional electrocatalytic performance for both ORR and OER which was higher than Pt/C catalyst. Promising ORR performance of FCNC900 can be simply be judged from E-1/2 = 0.868 V (vs. RHE) and E-onset = 1.01 V (vs. RHE) while OER overpotential for same catalyst was 360 mV much smaller than others. Longer stability and high methanol tolerance of this catalyst was also investigated.