An Efficient Bio-inspired Oxygen Reduction Reaction Catalyst: MnO_x Nanosheets Incorporated Iron Phthalocyanine Functionalized Graphene

Oxygen reduction reaction (ORR) catalysts play a critical role in energy storage and conversion devices and have been attracted enormous interests, and however, it remains challenging to develop highly active cheap catalysts in a simple and green route. Inspired by the heme-copper oxidases (HOCs), in which the ORR active center is originated from the incorporation of Fe-N-4 with copper atom, we here developed a fine manganese oxide nanosheets (MnOx NSs) integrated with iron phthalocyanine (FePc) anchored on highly conductive graphene (MnOx/FePc-G) through a green route only involve ethanol as the reagent. The bio-inspired catalyst MnOx/FePc-G demonstrated high ORR activity with a half-wave potential (E-1/2) of 0.887 V, about 57 mV more positive than that of Pt/C. And the current density (j) at 0.9 V is about 1.9 mA cm(-2), which is three times of Pt/C and FePc-G. More importantly, the bio-inspired systems show superior stability in comparison to commercial Pt/C, showing a potential of 0.863 V to deliver a j of 3 mA cm(-2) after 18 000 s polarization, about 80 mV higher than that of 0.783 V for Pt/C. The high activity is contributed by the integration of the FePc and MnOx NSs that plays the role to assist the cleavage of the O-2 bond. Our approach provides a new evidence to develop highly efficient ORR catalysts through imitate the naturally involved systems through a simple route.