High loading of single atomic iron sites in Pyrolysed Fe–NC oxygen reduction catalysts for proton exchange membrane fuel cells - Institut Charles Gerhardt - Institut de Chimie Moléculaire et des Matériaux de Montpellier Accéder directement au contenu
Article Dans Une Revue Nature Catalysis Année : 2022

High loading of single atomic iron sites in Pyrolysed Fe–NC oxygen reduction catalysts for proton exchange membrane fuel cells

Résumé

Non-precious iron-based catalysts (Fe–NCs) require high active site density to meet the performance targets as cathode catalysts in proton exchange membrane fuel cells. Site density is generally limited to that achieved at a 1–3 wt%(Fe) loading due to the undesired formation of iron-containing nanoparticles at higher loadings. Here we show that by preforming a carbon–nitrogen matrix using a sacrificial metal (Zn) in the initial synthesis step and then exchanging iron into this preformed matrix we achieve 7 wt% iron coordinated solely as single-atom Fe–N4 sites, as identified by 57Fe cryogenic Mössbauer spectroscopy and X-ray absorption spectroscopy. Site density values measured by in situ nitrite stripping and ex situ CO chemisorption methods are 4.7 × 1019 and 7.8 × 1019 sites g−1, with a turnover frequency of 5.4 electrons sites−1 s−1 at 0.80 V in a 0.5 M H2SO4 electrolyte. The catalyst delivers an excellent proton exchange membrane fuel cell performance with current densities of 41.3 mA cm−2 at 0.90 ViR-free using H2–O2 and 145 mA cm−2 at 0.80 V (199 mA cm−2 at 0.80 ViR-free) using H2–air

Domaines

Chimie
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Dates et versions

hal-03831975 , version 1 (16-01-2023)

Identifiants

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Asad Mehmood, Mengjun Gong, Frédéric Jaouen, Aaron Roy, Andrea Zitolo, et al.. High loading of single atomic iron sites in Pyrolysed Fe–NC oxygen reduction catalysts for proton exchange membrane fuel cells. Nature Catalysis, 2022, 5 (4), pp.311 - 323. ⟨10.1038/s41929-022-00772-9⟩. ⟨hal-03831975⟩
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