What question did this study set out to answer?

To identify the mechanisms governing iron demetallation in Fe-N-C electrocatalysts under acidic fuel cell conditions and to test strategies for suppressing metal dissolution.

April 8, 2016ACS Catalysis

Minimizing Operando Demetallation of Fe-N-C Electrocatalysts in Acidic Medium

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Authors

CCChang Hyuck ChoiPohang University of Science and Technology CBClaudio BaldizzoneRobert Bosch (Netherlands)GPGeorge PolymerosUniversity of West Attica

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Implication

Mechanistic study uncovers potential-dependent iron dissolution in acidic fuel cell catalysts, indicating that suppressing demetallation does not prevent short-term performance decay.

Key Points

To identify the mechanisms governing iron demetallation in Fe-N-C electrocatalysts under acidic fuel cell conditions and to test strategies for suppressing metal dissolution.
Tracked iron dissolution behavior during potential cycling using operando spectroscopic analysis in acidic electrolyte.
Developed and evaluated two particle-removal strategies: synthesizing Fe-N-C catalysts completely free of iron particles and removing exposed particles postsynthesis via electrochemical potential control or chemical reduction with SnCl2.
Assessed electrocatalytic oxygen reduction reaction (ORR) activity and conducted short-term polymer electrolyte membrane fuel cell (PEMFC) durability tests.
Operando spectroscopy revealed that standard acid washing fails to remove inactive iron particles because a high open circuit potential (~0.9 V vs RHE) forms insoluble ferric species, which subsequently dissolve into soluble ferrous cations under cathode operating conditions (<0.7 V vs RHE).
Both synthetic exclusion of iron particles and postsynthetic reduction substantially lowered operando demetallation during voltammetric protocols without significantly altering initial ORR activity.
Despite dramatically reduced iron dissolution, both modified and unmodified catalysts experienced similar performance decay in short-term PEMFC durability tests, indicating that leached ferrous cations from inactive particles do not drive early degradation.

Cite This Study

Choi et al. (2016) studied this question.

synapsesocial.com/papers/6a703377439bab0cabc30f4a https://doi.org/10.1021/acscatal.6b00643

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Implication

Mechanistic study uncovers potential-dependent iron dissolution in acidic fuel cell catalysts, indicating that suppressing demetallation does not prevent short-term performance decay.

Minimizing Operando Demetallation of Fe-N-C Electrocatalysts in Acidic Medium

Discussion

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Implication

Key Points

Cite This Study

Minimizing Operando Demetallation of Fe-N-C Electrocatalysts in Acidic Medium

Discussion

Member takes

Implication

Key Points

Cite This Study

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