Fe–N–C Catalyst Graphitic Layer Structure and Fuel Cell Performance

For targeted development of platinum group metal-free (PGM-free) catalysts for proton exchange membrane fuel cell applications, it is critically important to elucidate the catalytic moieties of Fe–N–C materials as they relate to the structure and morphology of the graphitic layers of carbon, the catalyst basic building blocks. In this Letter, X-ray diffraction analysis with a carbon-specific structure refinement algorithm was performed on 12 Fe–N–C catalysts. Samples with fewer graphitic layers exhibit increased kinetic performance in fuel cell testing. This trend is consistent with the dominant active species residing within the graphitic plane as opposed to at the edges. We also report the performance of an optimized catalyst based on structure–property predictions derived in a recently published report. This catalyst produces 0.44 mA cm–2 at 0.85 V and has a maximum power density of 490 mW cm–2 in 1 bar O2 (not iR corrected).