Atomically dispersed Fe-N-C derived from dual metal-organic frameworks as efficient oxygen reduction electrocatalysts in direct methanol fuel cells

摘要

The rational design of highly efficient, low-cost and methanol-tolerant catalysts toward the oxygen reduction reaction (ORR) is urgently desired for the commercialization of direct methanol fuel cells (DMFCs). Herein, a novel Fe-N-C catalyst (ZIF/MIL-10-900) is derived from a mixture of ZIF-8 and MIL-101(Fe) and atomically dispersed FeN4 structures are confirmed by Mossbauer spectra and X-ray absorption spectroscopy. Study on the pyrolysis procedure reveals that Fe atoms in FeN4 are from MIL-101(Fe), while ZIF-8 acts as structural support and nitrogen sources. The as-prepared catalyst demonstrates a comparable ORR activity with the commercial Pt/ C possessing a half-wave potential (E-1/2) of 0.78 V in acids, in combination with excellent methanol tolerance and stability. One of the highest peak power density of 83 mW cm(-2) in DMFC (3 M CH3OH) by adopting ZIF/MIL-10-900 as cathode catalyst is obtained, which is 2.8-fold higher than that of the commercial Pt/C in the same operating condition.