Nanoporous bimetallic Zn/Fe-N-C for efficient oxygen reduction in acidic and alkaline media
It remains a major challenge to develop a facile method to prepare non-noble metal electrocatalysts with high activity and durability to drive the sluggish oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs). Herein, a highly efficient bimetallic Zn/Fe@N-doped hierarchical porous carbon (Zn/Fe-N-C) catalyst derived from ZIF-8 and hemin (host-guest) was firstly reported by one-step thermal treatment. The spatial separation of Fe2+ by using hemin guest in ZIF-8 framework and its unique hydrocarbon branched chain form rich Fe-Nx active sites, and the evaporation of Zn2+ generates highly porous structure in the Zn/Fe-N-C catalysts. Benefitting from this unique structure and composition, the resultant Zn/Fe2-N-C catalyst exhibits excellent ORR activity in both 0.1 M KOH media (onset potential, Eonset = 1.08 V and half-wave potential, E1/2 = 0.86 V vs RHE) and 0.5 M H2SO4 media (Eonset = 1.04 V and E1/2 = 0.81 V), which is even comparable to the commercial Pt/C catalyst and ranks among the top of reported electrocatalysts. In addition, it also has outstanding long-term durability as well as good methanol resistance, much better than Pt/C in both acidic and alkaline media, which makes it one of the best non-noble alternatives of Pt-based catalysts for ORR electrocatalysis. This work highlights the potential to rational design and fabricate high performance ORR catalysts for the fuel cell applications.
- This article is part of the themed collection: Journal of Materials Chemistry A HOT Papers