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
Hauptverfasser: Farber, Eliyahu M, Ojha, Kasinath, Burshtein, Tomer Y, Hasson, Lihi, Eisenberg, David
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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.
ISSN:2633-5409
2633-5409
DOI:10.1039/d0ma00084a