The Solid‐Phase Synthesis of an Fe‐N‐C Electrocatalyst for High‐Power Proton‐Exchange Membrane Fuel Cells

Abstract

The environmentally friendly synthesis of highly active Fe-N-C electrocatalysts for proton-exchange membrane fuel cells (PEMFCs) is desirable but remains challenging. A simple and scalable method is presented to fabricate Fe II -doped ZIF-8, which can be further pyrolyzed into Fe-N-C with 3wt% of Fe exclusively in Fe-N 4 active moieties.Significantly,this Fe-N-C derived acidic PEMFC exhibits an unprecedented current density of 1.65 Acm À2 at 0.6 Vand the highest power density of 1.14 Wcm À2 compared with previously reported NPMCs.T he excellent PEMFC performance can be attributed to the densely and atomically dispersed Fe-N 4 active moieties on the small and uniform catalyst nanoparticles.Proton-exchange membrane fuel cells (PEMFCs) are ideal clean-energy systems that efficiently convert the chemical energy of hydrogen/oxygen into electricity through electrochemical reactions. [1] Theapplication of PEMFCs is,however, hindered by the scarcity and intolerable cost of the precious metal Pt, which is the most efficient catalyst so far for oxygen reduction reaction (ORR), and accounts for about 40 %ofthe fuel cell cost. [2] As anon-precious metal catalyst (NPMC), Fe-N-C decorated with Fe-N 4 active moieties has emerged as ap romising alternative to Pt for its high initial performance close to commercial Pt/C(20 %) in acidic PEMFCs. [3] The maximum power densities (P max )o ft hese Fe-N-C derived PEMFCs have reached above 0.9 Wcm À2 or even over 1Wcm À2 to date (the largest P max of 1.06 Wcm À2 was achieved at 2bar H 2 /O 2 @80 8 8Cin2 017). [4] Although the three-electrode system (half-cell) is efficient for afast judgement of the NPMC catalytic activity,PEMFC measurement is more valuable for comprehensively evaluating catalyst properties in the actual working condition. [5] The NPMC fuel cell performance is commonly determined by two factors.O ne is the mass transport property of the catalyst layer, which influences the utilization of the active sites and the polarization of the fuel cell; [6] theo ther is the catalyst parameters,i ncluding the composition and the dispersion density of active sites,a nd the catalyst morphology and size, Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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