Understanding the self-templating of hierarchically porous carbon electrocatalysts using Group 2 coordination polymers
Self-templating of hierarchical porosity in carbon materials can be realized by the pyrolysis of well-designed metal-organic precursors. While this strategy is elegant and scalable, detailed mechanistic understanding of the self-templating process is lacking. We now report a systematic investigation...
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Veröffentlicht in: | Materials advances 2020-04, Vol.1 (1), p.2-33 |
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Hauptverfasser: | , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Self-templating of hierarchical porosity in carbon materials can be realized by the pyrolysis of well-designed metal-organic precursors. While this strategy is elegant and scalable, detailed mechanistic understanding of the self-templating process is lacking. We now report a systematic investigation of the microstructural evolution in porous carbons, including hierarchically micro-/meso-/macroporous materials with variable mesopore size. We focus on a homologous series of well-defined metal-organic coordination polymers, combining the highly abundant Group 2 ions (Mg
2+
, Ca
2+
, Sr
2+
, Ba
2+
) with a common ligand. To understand the role of the metal ion in directing the morphology of the ultimate N-doped carbons, we performed a detailed investigation using electron microscopy (HRSEM, HRTEM, EDS), N
2
porosimetry, XRD, XPS and Raman spectroscopy. The rich morphological variations in the carbons determine their activity as metal-free electrocatalysts towards the oxygen reduction reaction. In particular, the reaction selectivity (2e
−
vs.
4e
−
pathways) is directed by competition between kinetics and mass transfer, due to confinement in mesopores.
Hierarchical porosity in carbon materials can be realized by self-templating: controlled pyrolysis of well-designed metal-organic precursors. |
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ISSN: | 2633-5409 2633-5409 |
DOI: | 10.1039/d0ma00084a |