1. Resolving the dilemma of Fe-N-C catalysts by the selective synthesis of tetrapyrrolic active sites via an imprinting strategyTim-Patrick Fellinger, Beate Paulus, Miran Gaberšček, Francisco Ruiz-Zepeda, Friedrich Wagner, Burak Koyutürk, Iztok Arčon, Yan-Sheng Li, Jian Liang Low, Davide Menga, 2021, original scientific article Abstract: Combining the abundance and inexpensiveness of
their constituent elements with their atomic dispersion, atomically
dispersed Fe−N−C catalysts represent the most promising
alternative to precious-metal-based materials in proton exchange
membrane (PEM) fuel cells. Due to the high temperatures
involved in their synthesis and the sensitivity of Fe ions toward
carbothermal reduction, current synthetic methods are intrinsically
limited in type and amount of the desired, catalytically active Fe−
N4 sites, and high active site densities have been out of reach
(dilemma of Fe−N−C catalysts). We herein identify a paradigm
change in the synthesis of Fe−N−C catalysts arising from the
developments of other M−N−C single-atom catalysts. Supported
by DFT calculations we propose fundamental principles for the synthesis of M−N−C materials. We further exploit the proposed
principles in a novel synthetic strategy to surpass the dilemma of Fe−N−C catalysts. The selective formation of tetrapyrrolic Zn−N4
sites in a tailor-made Zn−N−C material is utilized as an active-site imprint for the preparation of a corresponding Fe−N−C catalyst.
By successive low- and high-temperature ion exchange reactions, we obtain a phase-pure Fe−N−C catalyst, with a high loading of
atomically dispersed Fe (>3 wt %). Moreover, the catalyst is entirely composed of tetrapyrrolic Fe−N4 sites. The density of
tetrapyrrolic Fe−N4 sites is more than six times as high as for previously reported tetrapyrrolic single-site Fe−N−C fuel cell catalysts
Found in: osebi
Keywords: Fe-N-C catalysts, selective synthesis, tetrapyrrolic active sites, EXAFS, XANES, single atom, DFT
Published: 25.10.2021; Views: 1112; Downloads: 49
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