Intermetallic based materials for Sabatier reaction: Surface understanding, performance assessment and comparison with commercial catalyst

Freccero, Riccardo; Spennati, Elena; Garbarino, Gabriella; Riani, Paola

doi:10.1016/j.apcatb.2023.123532

Cited by 4 publications

(1 citation statement)

References 79 publications

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“…The resulting catalyst powders contain FeN 4 centers that are attributed as active sites. − However, the reports on the nature of the coordinating nitrogen ligands, i.e., pyrrolic or pyridinic, − differ as well as the discussion of their contribution toward degradation . On top of this, the pyrolysis process also generates inorganic side phases alongside the desired moieties. − Side phases can be of metallic, carbidic, nitridic, or oxidic nature. ,− These undesired side phases can leach out during FC operation, and the resulting iron ions can further accelerate the degradation, e.g., by Fenton’s reaction and formation of radical oxide species (ROS) . Choi et al observed iron leaching from a ZIF-based FeNC catalyst synthesized solely by pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Stability of FeNC Catalysts in PEMFCs by Improved Purification

Gridin,

Segura-Salas,

Saveleva

et al. 2024

ACS Catal.

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FeNC catalysts are very promising candidates for the oxygen reduction reaction in proton exchange fuel cells (FCs). Their preparation is dominated by pyrolysis approaches, which however lead also to the formation of inorganic impurity species. While a subsequent removal of iron access is thus desirable, even after acid leaching (AL), some side phases still remain in the catalyst. Such species might leach out during operation and cause severe degradation by Fenton's reaction and subsequent formation of reactive oxygen species. However, it remains under debate if iron from the catalytically active FeN 4 centers also contributes in this degradation mechanism. To get further insights, different strategies to improve the AL are compared with respect to structural (XAS, XES, and ICP) and morphological (TEM, Raman, and hydrophobicity) changes and their impact on the activity and more important stability of FeNC catalysts. In all cases, the iron content was significantly reduced. While the positive impact of purification on the performance in half-cell measurements is not obvious, almost doubling of the FC activity is observed, which goes hand in hand with an improved stability. Thus, this work underlines the importance of thorough ex situ leaching to avoid severe degradation.

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