Hydrogen Passivation of M-N-C (M = Fe, Co) Catalysts for Storage Stability and ORR Activity Improvements.
basic_science · Level V
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- Record sourced from PubMed, PMID 34365694.
- Also identified by DOI 10.1002/adma.202103600.
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Abstract
M-N-C (M = Fe, Co) are highly active nonprecious metal electrocatalysts for the oxygen reduction reaction (ORR) and other applications. Although their operation stability has been extensively studied in proton-exchange-membrane fuel cells, the storage stability that determines the performance maintenance before use has not yet been understood. Here, it is found that long-term exposure of M-N-C catalysts in air would cause surface oxidation and hydroxylation, resulting in significant decrease of ORR activity and fuel-cell performances. Hydrogen passivation is demonstrated to be an effective strategy to protect the atomic M-N<sub>4</sub> active sites and improve the storage stability of the catalysts. In addition, the hydrogen-termination can also reduce the ORR energy barrier and increase the utilization of active sites, leading to the improvements of fuel-cell activity and power density. Notably, these findings help to understand the storage-associated degradation and protection of M-N-C catalysts.