Understanding the Catalytic Sites of Metal-Nitrogen-Carbon Oxygen Reduction Electrocatalysts.
Chemistry
; 27(1): 145-157, 2021 Jan 04.
Article
em En
| MEDLINE
| ID: mdl-32706127
ABSTRACT
The development of low-cost catalysts containing earth-abundant elements as alternatives to Pt-based catalysts for the oxygen reduction reaction (ORR) is crucial for the large-scale commercial application of proton exchange membrane fuel cells (PEMFCs). Nonprecious metal-nitrogen-carbon (M-N-C) materials represent the most promising candidates to replace Pt-based catalysts for PEMFCs applications. However, the high-temperature pyrolysis process for the preparation of M-N-C catalysts frequently leads to high structural heterogeneity, that is, the coexistence of various metal-containing sites and N-doped carbon structures. Unfortunately, this impedes the identification of the predominant catalytic active structure, and thus, the further development of highly efficient M-N-C catalysts for the ORR. This Minireview, after a brief introduction to the development of M-N-C ORR catalysts, focuses on the commonly accepted views of predominant catalytic active structures in M-N-C catalysts, including atomically dispersed metal-Nx sites, metal nanoparticles encapsulated with nitrogen-doped carbon structures, synergistic action between metal-Nx sites and encapsulated metal nanoparticles, and metal-free nitrogen-doped carbon structures.
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MEDLINE
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En
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2021
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Article